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HONG KONG PROGRAMS
PHIL 101: FUNDAMENTALS OF PHILOSOPHY (4) (2H)
Spring quarter, 2004 (March 22-June 8)
David C. Lam Building, HKBU Campus
Instructor: Dr. Giuseppe Mario Saccone
E-mail: gmsaccon@graduate.hku.hk
Tel: 98660230
LECTURE 1: What is philosophy?
What is Philosophy? Why should we learn it?
What is philosophy? Philosophy can mean different things to different people. Etymologically
speaking, philosophy means ‘Love of Wisdom.’ It includes both theory and practise, view and way,
end and means, beginning (alpha) and end (omega), or science and art. Its meanings seem to depend
on each school of thought. Philosophers, therefore, may be considered as sages, lovers of wisdom,
lovers of argument, theorists, practitioners, or even artists.
There are various currents of academic philosophy. We can speak of Eastern and Western
philosophy. Western philosophy at the moment can be divided into two main kinds: analytic
(Anglo-American or English speaking) and continental (European) philosophy. The two kinds of
philosophy pay attention to language and being. However, while analytic philosophy mainly deals
with truths and knowledge, continental philosophy (primarily) deals with values and life. From
these observations, it may be said that analytic philosophy is a close friend of science whereas most
school of continental philosophy are close friend of religion. Turning to Eastern philosophy, we
may surprisingly discover that all schools of thought believe that reality is a social process. In other
words, according to Eastern philosophy, all actual realities are becomings, not beings.
Philosophy literally means love of wisdom, the Greek words philia meaning love or friendship, and
Sophia meaning wisdom. Philosophy is concerned basically with three areas: epistemology (the
study of knowledge), metaphysics (the study of the nature of reality), and ethics (the study of
morality).
Epistemology deals with the following questions: what is knowledge? What are truth and falsity,
and to what do they apply? What is required for someone to actually know something? What is the
nature of perception, and how reliable is it? What are logic and logical reasoning, and how can
human beings attain them? What is the difference between knowledge and belief? Is there anything
as “certain knowledge”?
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Metaphysics is the study of the nature of reality, asking the questions: What exists in reality and
what is the nature of what exists? Specifically, such questions as the following are asked: Is there
really cause and effect in reality, and if so, how does it work? What is the nature of the physical
world, and is there anything other than the physical such as the mental or spiritual? What is the
nature of human beings? Is there freedom in reality or is everything predetermined?
Ethics deals with what is right or wrong in human behaviour and conduct. It asks such questions as
what constitutes any person or action being good, bad, right, or wrong, and how do we know
(epistemology)? What part does self-interest or the interest of others play in the making of moral
decisions and judgements? What theories of conduct are valid or invalid, and why? Should we use
principles or rules or laws, or should we let each situation decide our morality? Are killing, lying,
cheating, stealing, and sexual acts right or wrong, and why or why not?
Love of wisdom
The term philosophy literally means the love of wisdom. It is said that the first one to call himself a
philosopher was Pythagoras, a Greek who lived somewhere between 570 and 495 B.C. and spent
most of his life in southern Italy. He is, of course, best known for his famous mathematical
theorem. When once asked is he was wise, he replied that no one could be wise but a god, but that
he was a lover of wisdom. To love something does not mean to possess it but to focus our life on it.
Whereas Pythagoras introduced the term philosopher, it was Socrates who made it famous. He said
that the philosopher was one who had a passion for wisdom and who was intoxicated by this love.
This description makes quite a contrast with the image of the philosopher as being cold and
analytical – sort of a walking and talking computer. On the contrary, the cognitive and the
emotional are combined in philosophy, for we do not rationally deliberate about those issues in life
that are deeply trivial. Those issues that are most important to us are such things as our religious
commitments (or lack of them), our moral values, our political commitments, our career, or
(perhaps) who we will share our lives with. Such issues as our deepest loves, convictions, and
commitments demand our deepest thought and most through rational reflection. Philosophy, in part,
is the search for that kind of wisdom that will inform the beliefs and values that enter into these
crucial decisions.
Socrates’ method
If wisdom is the most important goal in life to Socrates, how did he go about pursuing it? Socrates
method of doing philosophy was to ask questions. That method was so effective that it has become
one of the classic techniques of education; it is known as the Socratic method, or Socratic
questioning. Plato referred to the method as dialectic, which comes from a Greek word for
conversation. Typically, Socrates’ philosophical conversations go through seven stages as he and
his partner continually move toward a greater understanding of the truth:
1 Socrates unpacks the philosophical issues in an everyday conversation. (The genius of Socrates
was his ability to find the philosophical issues lurking in even the most mundane of topics.)
2 Socrates isolates a key philosophical term that needs analysis.
3 Socrates professes ignorance and requests the help of his companion.
4 Socrates’ companion proposes a definition of the key term.
5 Socrates analyzes the definition by asking questions that expose its weaknesses.
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6 The subject produces another definition, one that improves on the earlier one. (This new
definition leads back to step 5, and on close examination the new definition is once again found to
fail. Steps 5 and 6 are repeated several times.)
7 The subject is made to face his own ignorance. (Finally, the subject realizes he is ignorant and is
now ready to begin the search for true wisdom. Often, however, the subject finds some excuse to
end the conversation or someone else makes an attempt at a new definition.)
Socrates’ hope in utilizing this method was that in weeding out incorrect understandings, he and his
conversational partner would be moving toward a clearer picture of the true answer. Since Socrates
believed that the truth about the ultimate issues in life lay deeply hidden within us, this process of
unpacking the truth within was like that of a midwife helping a mother in labour bring forth her
child.
One of Socrates’ most skilful techniques for showing the weakness of someone’s position was his
use of the reductio ad absurdum form of argument. This term means “reducing to an absurdity.”
Socrates would begin by assuming that his opponent’s position is true and then show that it
logically implies either an absurdity or a conclusion that contradicts other conclusions held by the
opponent. Deducing a false statement from a proposition proves that the original assumption was
false.
Reductio ad Absurdum Arguments
The label of the reduction ad absurdum argument, a valid argument form, means reducing to an
absurdity. To use this technique, you begin by assuming that your opponent’s position is true and
then you show that it logically implies either an absurd conclusion or one that contradicts itself or
that it contradicts other conclusions held by your opponent. Deducing a clearly false statement from
a proposition is definitive proof that the original assumption was false and is a way of exposing an
inconsistency that is lurking in an opponent’s position. When the reduction ad absurdum argument
is done well, it is an effective way to refute a position.
1 Suppose the truth of A (the position that you wish to refute).
2 If A, then B.
3 If B, then C.
4 If C, then not-A.
5 Therefore, both A and not-A
6 But 5 is a contradiction, so the original assumption must be false and not-A must be true.
Philosophical example of a Reductio ad Absurdum
Socrates’ philosophical opponents, the Sophists, believed that all truth was subjective and relative.
Protagoras, one the most famous Sophists, argued that one opinion is just as true as another opinion.
The following is a summary of the argument that Socrates used to refute this position as Plato tell
us (Theaetetus, 171a,b):
1 One opinion is just as true as another opinion. Socrates assumes the truth of Protagoras’s
position.)
2 Protagoras’s critics have the following opinion: Protagoras’s opinion is false and that of his critics
is true.
3 Since Protagoras believe premise 1, he believes that the opinion of his critics in premise 2 is true.
4 Hence, Protagoras also believes it is true that: Protagoras’s opinion is false and that of his critics
is true.
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5 Since individual opinion determines what is true and everyone (both Protagoras and his critics)
believe the statement “Protagoras’s opinion is false”, it follows that
6 Protagoras’s opinion is false.
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LECTURE 2: The basic concepts of logic
Logic is the study of the methods and principles used to distinguish correct reasoning from
incorrect reasoning and is a tool for figuring out everything that can truthfully be said, based on
what is already known to be true. For this reason, it is related to epistemology, i.e., the theory of
knowledge, but its range of application cover the evaluations of arguments in every field of
knowledge including metaphysics and ethics. There are objective criteria with which correct
reasoning may be defined. If these criteria are not known, they cannot be used. The aim of logic is
to discover and make available those criteria that that can be used to test arguments, and to sort
good arguments from bad ones.
The logician is concerned with reasoning on every subject: science and medicine, metaphysics,
ethics and law, politics and commerce, sports and games, and even the simple affairs of everyday
life. Very different kinds of reasoning may be used, and all are of interest to the logician, but his
concern throughout will be not with the subject matter of those arguments, but with their form and
quality. His aim is how to test arguments and evaluate them.
It is not the thought processes called reasoning that are the logician’s concern, but the outcomes of
these processes, the arguments that are the products of reasoning, and that can be formulated in
writing, examined, and analyzed. Each argument confronted raises this question for the logician:
Does the conclusion reached follow from the premises used or assumed? Do the premises provide
good reasons for accepting the conclusion drawn?
The origins of logic
In Western intellectual history there have been three great periods of development in logic, with
somewhat barren periods sandwiched between them. The first great period was ancient Greece
between about 400 BC and 200 CE. The most influential figure here is Aristotle (384-322) who
developed a systematic theory of inferences called “syllogisms”.
It should also be mentioned that at around the same time as all this was happening in Greece,
theories of logic were being developed in India, principally by Buddhist logicians.
The second growth period in Western logic was the in the medieval European universities, such as
Paris and Oxford, from the 12th
to the 14th
centuries.
After this period, logic largely stagnated till the second half of the 19th
century.
The development of abstract algebra in the 19th
century triggered the start of third and possibly the
greatest of the three periods. The logical theories developed in the third period are normally referred
as modern logic, as opposed to the traditional logic that preceded it. Developments in logic
continued apace throughout the 20th century and show no sign of slowing down yet.
“Arguments” in logic
As we have seen, it is with arguments that logic is chiefly concerned. An argument is a cluster of
propositions in which one is the conclusion and the other(s) are premises offered in its support. This
means that in understanding and constructing arguments, it is particularly important to distinguish
the conclusion from the premises. Indicator words can help us to do this: words like therefore, thus,
so, consequently tell us which claims are to be justified by evidence and reasons, and since,
because, for, as, as indicated by, in view of the fact that which other claims are put forward as
premises to support them. However, indicator words are not infallible signs of argument because
some arguments do not contain indicator words, and some indicator words may appear outside the
context of arguments.
Arguments may be analyzed and illustrated either by paraphrasing, in which the propositions are
reformulated and arranged in logical order; or by diagramming, in which the propositions are
numbered and the numbers are laid out on a page and connected in ways that exhibit the logical
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relations among the propositions. To diagram we number each proposition in the order in which it
appears, circling the numbers. This avoids the need to restate the premises.
Nonarguments
Arguing and arguments are important as rational ways of approaching disputes and as careful
critical methods of trying to arrive at the truth. Speeches and texts that do not contain arguments
can be regarded as nonarguments. There are many different types of nonarguments – including
description, exclamation, question, joke, and explanation. Explanation are sometimes easily
confused with arguments because they have a somewhat similar structure and some of the major
indicator words for arguments are also used in explanations. Explanations should be distinguished
from arguments, however, because they do not attempt to justify a claim, or prove it to be true.
Recognizing arguments: deduction and induction
The difference between inductive and deductive arguments is deep, Because an inductive argument
can yield no more than some degree of probability for its conclusion it is always possible that
additional information will strengthen or weaken it. Newly discovered facts may cause us to change
our estimate of probabilities, and thus may lead us to judge the argument to be better or worse than
we thought it was. In the world of inductive argument – even when the conclusion is thought to be
very highly probable – all the evidence is never in. It is this possibility of new data, perhaps
conflicting with what was believed earlier, that keeps us from asserting that any inductive
conclusion is absolutely certain.
Deductive arguments, on the other hand, cannot gradually become better or worse. They either
succeed or do not succeed in exhibiting a compelling relation between premises and conclusion.
The fundamental difference between deduction and induction is revealed by this contrast. If a
deductive argument is valid, no additional premises could possibly add to the strength of that
argument. For example, if all humans are mortal, and is Socrates is human, we may conclude
without reservation that Socrates is mortal – and that conclusion will follow from that premises no
matter what else may be true in the world, and no matter what other information may be discovered
or added.
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LECTURE 3: The 3 Laws of Thought
Some early thinkers, after having defined logic as the science of the laws of thought, went on to
assert that there are exactly three basic laws of thought, laws so fundamental that obedience to them
is both the necessary and the sufficient condition of correct thinking. These three laws have
traditionally been called:
1 The principle of identity.
This principle asserts that if any statement is true, then it is true. Using our notation we may
rephrase it by saying that the principle of identity asserts that every statement of the form
p ⊃ p must be true, that every such statement is a tautology (a tautology is a statement which uses
different words to same the same thing). From this follows that
1 Prem.
a=a [This is an axiom – a basic assertion that is not proved but can be used to prove other things.
The rule of self-identity says that that we may assert a self-identity as a derived step anywhere in a
proof, no matter what the earlier lines are.]
and that
2 a=b :: b=a
and that
3 Fa
a = b
Fb [This is the equals may substitute for equals rule which is based on the idea that identicals are
interchangeable. If a=b, then whatever is true of a is also true of b, and vice versa. This rule holds
regardless of what constants replace a and b and what well formed formulas replace Fa and Fb
provided that the two well formed formulas are alike except that the constants are interchanged in
one or more occurrences.]
2 The principle of non contradiction.
This principle assets that no statement can be both true and false. Using our notation we may
rephrase it by saying that the principle of non contradiction asserts that every statement of the form
p ∙ ∼p must be false, that every such statement is self contradictory.
3 The principle of excluded middle.
This principle asserts that every statement is either true or false.
Using our notation we may rephrase it by saying that the principle of excluded middle asserts that
every statement of the form p ∨ ∼p must be true, that every such statement is a tautology.
It is obvious that these 3 principles are indeed true, logically true – but the claim that they deserve a
privileged status as the most fundamental laws of thought is doubtful. The first (identity) and the
third (excluded middle) are tautologies, but there are many other tautologous forms whose truth is
equally certain. And the second (non contradiction) is by no means the only self-contradictory form
of statement.
We do use these principles in completing truth tables. In the initial columns of each row of a table
we place either a T or an F, being guided by the principle of excluded middle. Nowhere do we put
both T and F together, being guided by the principle of non-contradiction. And once having put a T
under a symbol in a given row, then (being guided by the principle of identity) when we encounter
that symbol in other columns of that row we regard it as still being assigned a T. So we could
regard the three laws of thought as principles governing the construction of truth tables.
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Nevertheless, some thinkers, believing themselves to have devised a new and different logic, have
claimed that these 3 principles are in fact not true, and that obedience to them has been needlessly
confining.
The principle of identity has been attacked on the ground that things change, and are always
changing. Thus for example, statements that were true of the United States when it consisted of the
13 original states are no longer true of the United States today with 50 states. But this does not
undermine the principle of identity. The sentence “There are only thirteen states in the United
States” is incomplete, an elliptical formulation of the statement that “There were only 13 states in
the United States in 1790” and that statement is as true today as it was in 1790. When we confine
our attention to complete, non-elliptical formulation of propositions, we see that their truth (or
falsity) does not change over time. The principle of identity is true, and does not interfere with our
recognition of continuing change.
The principle of non-contradiction has been attacked by Hegelian and Marxists on the ground that
genuine contradiction is everywhere pervasive, that the world is replete with the inevitable conflict
of contradictory forces. That there are conflicting forces in the real world is true, of course - but to
call these conflicting forces contradictory is a loose and misleading use of that term. Labour unions
and the private owners of industrial plants may indeed find themselves in conflict – but neither the
owner nor the union is the negation or the denial or the contradictory of the other. The principle of
contradiction, understood in the straightforward sense in which it is intended by logicians, is
unobjectionable and perfectly true.
The principle of excluded middle has been the object of much criticism, on the grounds that it leads
to a two-valued orientation which implies that things in the world must be either white or black, and
which therefore hinders the realization of compromise and less than absolute gradations. This
objection also arises from misunderstanding. Of course the statement “This is black” cannot be
jointly true with the statement “This is white” – where “this” refers to exactly the same thing. But
although these two statements cannot both be true, they can both be false. “This” may be neither
black nor white; the two statements are contraries, not contradictories. The contradictory of the
statement “This is white” is the statement “It is not the case that this is white” and (if “white” is
used in precisely the same sense in both of these statements) one of them must be true and the other
false. The principle of excluded middle is inescapable.
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Deductive arguments: Validity and truth
A successful deductive argument is valid. This means that the conclusion follows with logical
necessity from the premises.
Remember that truth and falsity are attributes of individual propositions or statements; validity and
invalidity are attributes of arguments.
Just as the concept of validity does not apply to single propositions, the concept of truth does not
apply to arguments.
There are many possible combinations of true and false premises a conclusions in both valid and
invalid arguments. Consider the following illustrative deductive arguments, each of which is
prefaced by the statement of the combination it represents.
I Some valid arguments contain only true propositions – true premises and a true conclusion:
All mammals have lungs.
All whales are mammals.
Therefore all whales have lungs.
II Some valid arguments contain only false propositions:
All four-legged creatures have wings.
All spiders have four legs.
Therefore all spiders have wings.
This argument is valid because, if its premises were true, its conclusion would have to be true also –
even though we know that in fact both the premises and the conclusion of this argument are false.
III Some invalid arguments contain only true propositions – all their premises are true, and their
conclusion are true as well:
If I owned all the gold in Fort Knox, then I would be wealthy.
I do not own all the gold in Fort Knox.
Therefore I am not wealthy.
IV Some invalid arguments contain only true premises and have a false conclusion. This can be
illustrated with an argument exactly like the previous one (III) in form, changed only enough to
make the conclusion false:
If Bill Gates owned all the gold in Fort Knox, then Bill Gates would be wealthy.
Bill Gates does not own all the gold in Fort Knox.
Therefore Bill Gates is not wealthy.
The premises of this argument are true, but its conclusion is false.
Such an argument cannot be valid because it is impossible for the premises of a valid argument to
be true and its conclusion to be false.
V Some valid arguments have false premises and a true conclusion:
All fishes are mammals.
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All whales are fishes.
Therefore all whales are mammals.
The conclusion of this argument is true, as we know; moreover it may be validly inferred from the
two premises, both of which are wildly false.
VI Some invalid arguments also have false premises and a true conclusion:
All mammals have wings.
All whales have wings.
Therefore all whales are mammals.
From examples V and VI taken together, it is clear that we cannot tell from the fact that an
argument has false premises and a true conclusion whether it is valid or invalid.
VII Some invalid arguments, of course, contain all false propositions – false premises and a false
conclusion:
All mammals have wings.
All whales have wings.
Therefore all mammals are whales.
Deductive arguments: Soundness
When an argument is valid, and all of its premises are true, we call it sound.
All whales are mammals.
All mammals are animals.
Hence, all whales are animals.
If the president does live in the White House, then he lives in Washington, D.C.
The president does live in the White House.
So, the president lives in Washington, D.C.
The conclusion of a sound argument obviously must be true – and only a sound argument can
establish the truth of its conclusion. If a deductive argument is not sound – that is, if the argument is
not valid, or if not all of its premises are true – it fails to establish the truth of its conclusion even if
in fact the conclusion is true.
To test the truth or falsehood of premises is the task of science in general, since premises may deal
with any subject matter at all. The logician is not interested in the truth or falsehood of propositions
so much as in the logical relations between them. By “logical” relations between propositions we
mean those relations that determine the correctness or incorrectness of the arguments in which they
occur. The task of determining the correctness or incorrectness of arguments falls squarely within
the province of logic. The logician is interested in the correctness even of arguments whose
premises may be false.
Why not confine ourselves to arguments with true premises, ignoring all others? Because the
correctness of arguments whose premises are not known to be true may be of great importance. In
science, for example, we verify theories by deducing testable consequences – but we cannot
beforehand which theories are true. In everyday life as well, we must often choose between
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alternative courses of action, deducing the consequences of each. To avoid deceiving ourselves we
must reason correctly about the consequences of the alternatives, taking each as a premise. If we
were interested only in arguments with true premises, we would not know which set of
consequences to trace out until we knew which of the alternative premises was true. But if we knew
which of the alternative premises was true, we would not need to reason about it at all, since our
purpose in reasoning was to help us decide which alternative premise to make true. To confine our
attention to arguments with premises known to be true would therefore be self-defeating.
Deductive arguments: Proving invalidity
1 See whether the premises are actually true and the conclusion is actually false. If they are, then
the argument is invalid. If they are not, or if you can’t determine whether the premises and the
conclusion are actually true or false, then go on to step 2.
2 See if you can conceive a possible scenario in which the premises would be true and the
conclusion false. If you can, then the argument is invalid. If you can’t, and it is not obvious to you
that the argument is valid, then go on to step 3.
3 Try to construct a counterexample to the argument – that is, a second argument that has exactly
the same form as the first argument, but whose premises are obviously true and whose conclusion is
obviously false. If you can construct such a counterexample, then the argument is invalid. If you
can’t, then it is usually safe to assume that the argument is valid.
Counterexample method of proving invalidity
First, determine the logical pattern, then the form of the argument that you are testing for invalidity,
using letters (A,B,C,D) to represent the various terms of the argument.
Then, construct a second argument that has exactly the same form as the argument you are testing
but that has premises that are obviously true and a conclusion that is obviously false.
Example: Some Republicans are conservative, and some Republicans are in favour of capital
punishment. Therefore, some conservatives are in favour of capital punishment.
Logical pattern
1 Some Republicans are conservatives.
2 Some Republicans are in favour of capital punishment.
3 Therefore, some conservatives are in favour of capital punishment.
(Note that in logic some means at least one it does not mean some but not all.)
Form
1 Some A’s are B.
2 Some A’s are C.
3 Therefore, some B’s are C’s.
Construct a second argument that has exactly the same form and that has obviously true premises
and an obviously false conclusion.
1 Some A’s are B. 1 Some fruits are apples (true)
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2 Some A’s are C. 2 Some fruits are pears (true)
3 Therefore, some B’s are C’s. 3 Some apples are pear (false)
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LECTURE 4: Propositional logic
Although categorical logic is the oldest developed in the Western philosophical tradition, it is not
now believed to be the most basic part of logic. This role is reserved for propositional logic.
Propositional logic studies arguments whose validity depends on “if then”, “and,” “or,” “not”, and
similar notions. We will cover the very basics of it.
The earliest development of propositional logic (known also as truth-functional logic or sentential
logic) took place among the Stoics, who flourished from about the third century B.C.E. until the
second century C.E. But it was in the late nineteenth and twentieth centuries that the real power of
truth-functional logic became apparent.
Modern symbolic logic is not encumbered (as Aristotelian logic was) by the need to transform
deductive arguments into syllogistic form. That task can be laborious. Freed from the need to make
such transformations, we can pursue the aims of deductive analysis more directly.
In modern logic it is not syllogisms (as in the Aristotelian tradition) that are central, but logical
connectives, the relations between elements that every deductive argument, syllogism or not, must
employ. The internal structure of propositions and arguments is the focus of modern logic.
The “logic of sentences” is one of the bases on which modern symbolic logic rests, and as such it is
important in such intellectual areas as set theory and the foundations of mathematics. It is also the
model for electrical circuits of the sort that are the basis of digital computing. But truth-functional
logic is also a useful tool in the analysis of arguments.
Therefore, the study of truth-functional logic can be beneficial in several ways. For one thing, it
allows us to learn something about the structure of language that we would not learn any other way.
For another, we get a sense of what it is like to work with a very precise, non-mathematical system
of symbols that is nevertheless very accessible to nearly any student willing to invest a modest
amount of effort. The model of precision and clarity that such systems provide can serve us well
when we communicate with others in ordinary language.
However, in order to understand the internal structure of propositions and argument we must master
the special symbols that are used in modern logical analysis. It is with them that we can more fully
achieve the central aim of deductive logic: to discriminate valid arguments from invalid arguments.
In sum, the symbolic notation of modern logic is an exceedingly powerful tool for the analysis of
arguments.
Symbols and translation
1 In propositional logic, the world conjunction refers to a compound statement. A compound
statement, such as “This lesson was stimulating, and I learned a lot, is symbolized by two variables
joined by a dot (for example p ∙ q ).
[If in any case we are unsure whether a statement is simple or compound, we must ask, “What does
the statement mean?” Does the statement consists of two simple statements? If it does, then it is
compound. If it doesn’t, then it is simple.]
For the purposes of propositional logic, the following words are all equivalent and can be
symbolized by the dot: and, but, yet, while, whereas, although, though, however.
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2 Negation is the use of the word “not” (or an equivalent word or phrase) to deny a statement. The
conventional symbol for negation is the tilde, ∼.
3 A disjunction is an “or” statement – that is, a statement that consists of two (or more) statements
set apart, usually by the word “or”. The symbol for disjunction is the lower case v, also called the
wedge. The word “or” has two possible senses. The exclusive sense eliminates one of the
possibilities. For example, a flight attendant may tell you, “For dinner you may have chicken or
fish.” The nonexclusive sense does not exclude either possibility. For example, a doctor may advise
you that “when you are feeling dehydrated, you should drink water or natural fruit juice.” It is true
when either of the two statement is true, and it is also true when both statements are true. For the
purposes of propositional logic, it is conventional to take the word “or” in its nonexclusive sense.
4 A conditional statement is an if-then statement consisting of two parts. The first part of the
statement, which follows “if” and precedes “then,” is called the antecedent. The symbol for the
implication involved in an if then statement is the horseshoe, ⊃. The only time a conditional is false
is when the antecedent is true and the conclusion is false. It may be helpful to think of the truth
table for conditional statements in terms of the guiding legal principle that a person is presumed
innocent until proven guilty. In a similar way, a conditional is presumed true until proven false. The
only thing that can definitively show that a conditional is false is a true antecedent followed by a
false consequent.
5 Any two true statements materially imply one another and any two false statements also
materially imply one another, since they are either both true, or both false. The symbol for material
equivalence is the triple bar sign ≡. We can read the triple bar sign to say “if and only if”. Two
statements are logically equivalent when the statement of their material equivalence is a tautology.
A tautology is a statement that it is true in every possible case. Statements that are logically
equivalent may be substituted for one another, while statements that are merely materially
equivalent cannot replace one another.
We now have a propositional language, with precise rules for constructing arguments and testing
validity. Our language can help to test arguments.
∼ P = Not P
(P ∙ Q) = Both P and Q
(P v Q) = Either P or Q
(P ⊃ Q) = If P then Q
(P ≡ Q) = P if and only if Q
A grammatically correct formula of this language is called a wff, or well formed formula
(pronounce woof – as in wood).
The truth value of any truth functional connective depends upon (is a function of) the truth or falsity
of the statements it connects.
Truth values for a variable (which stands for a statement) are indicated as true, T, or false, F.
Truth tables
A truth table is a listing of all possible truth values for the variables in an argument form.
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In a valid argument it is impossible for all of the premises to be true and the conclusion false. So in
examining the truth table, we look for instances in which all the premises are true. If there is any
instance of all true premises followed by a false conclusion, an F under the conclusion column, the
argument is invalid. It does not matter if there are other instances in the truth table where all the
premises are true and the conclusion is true, too.
Any two arguments that share the same argument form are either both valid or both invalid. When
we know that an argument form is valid, we know that any argument that fits that form is valid.
The truth tables for the five basic truth functional symbols
Negation: "not" or "it is not the case that"
P ∼P
T F
F T
Conjunction : and, but, while.
P Q (P ∙ Q)
T T T
T F F
F T F
F F F
Disjunction: or, unless
P Q (P v Q)
T T T
T F T
F T T
F F F
Conditional: if….then
P Q (P ⊃ Q)
T T T
T F F
F T T
F F T
Material equivalence: if and only if
P Q (P ≡ Q)
T T T
T F F
F T F
F F T
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Formal proof
When we use the method of deduction, we actually deduce (or derive) the conclusion from the
premises by means of a series of basic truth-functionally valid argument patterns. This is a lot like
thinking through the argument, taking one step at a time to see how, once we have assumed the
truth of the premises, we eventually arrive at the conclusion. The first few basic argument patterns
are referred to as truth-functional rules because they govern what steps we are allowed to take in
getting from the premise to the conclusion.
We define a formal proof that a given argument is valid as a sequence of statements each of which
is either a premise of that argument or follows from preceding statements of the sequence by an
elementary valid argument, such that the last statement in the sequence is the conclusion of the
argument whose validity is being proved.
We define an elementary valid argument as any argument that is a substitution instance of an
elementary valid argument form. One matter to be emphasized is that any substitution instance of
an elementary valid argument form is an elementary valid argument. Thus the argument
(A ∙ B) ⊃ [C ≡ (D ∨ E)]
(A ∙ B)
∴ C ≡ (D ∨ E)
is an elementary valid argument because it is a substitution instance of the elementary valid form
modus ponens (M.P.). It results from
p ⊃ q
p
∴ q
by substituting A ∙ B for p and C ≡ (D ∨ E) for q, and is therefore of that form even though modus
ponens is not the specific form of the given argument.
1 Modus ponens, also known as affirming the antecedent, is the most elementary among the rules of
inference, but the same process can be applied to all the others. It can be applied also to:
2 Modus tollens, also known as denying the consequent. If you have a conditional claim as one
premise and if one of your other premises is the negation of the consequent of that conditional, you
can write down the negation of the conditional’s antecedent as a new line in your deduction.
3 The pure hypothetical syllogism also known as chain argument rule allows you to derive a
conditional from two you already have, provided the antecedent of one of your conditionals is the
same as the consequent of the other.
4 Disjunctive argument, from a disjunction and the negation of one disjunct, the other disjunct may
be derived.
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5 Constructive dilemma, the disjunction of the antecedents of any two conditionals allows the
derivation of the disjunction of their consequents.
(p ⊃ q) ∙ (r ⊃ s)
p v r
∴ q v s
5b Destructive dilemma, the disjunction of the negations of the consequents of two conditionals
allows the derivation of the disjunction of the negations of their antecedents.
(p ⊃ q) ∙ (r ⊃ s)
∼q v ∼s
∴ ∼p v ∼r
God and Evil
An age old argument that God is either not all powerful or not all good goes like this:
If God is all powerful, then he would be able to abolish evil.
If God is all good, then he would not allow evil to be.
Either God is not able to abolish evil, or God allows evil to be.
Therefore, either God is not all powerful, or God is not all good.
(p ⊃ a) ∙ (g ⊃ ∼e)
∼a v e
∴ ∼p v ∼g
This argument is an instance of the destructive dilemma.
6 Simplification, if the conjunction is true, then of course the conjunct must all be true. You can
pull out one conjunct from any conjunction and make it the new line in your deduction.
7 Conjunction, this rules allows you to put any two lines of a deduction together in the form of a
conjunction.
p
q
∴ p ∙ q
8 Addition, clearly no matter what claims p and q might be, if p is true then either p or q must be
true. The truth one disjunt is all it takes to make the whole disjunction true.
p
∴ p v q
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Inconsistency
Consistency and inconsistency are important because, among other things, they can be used to
evaluate the overall rationality of a person’s stated position on something.
If truth values can be assigned to make all the premises of an argument true and its conclusion
false, than that shows the argument to be invalid. If a deductive argument is not invalid it must be
valid. So, if no truth-value assignment can be given to the component simple statements of an
argument that makes its premises true and its conclusion false, then the argument must be valid.
Although this follows from the definition of validity, it has a curious consequence. The essence of
the matter is simply shown in the case of the following argument, whose openly inconsistent
premises allow us validly to infer an irrelevant and fantastic conclusion:
Today is Sunday
Today is not Sunday
Therefore, the moon is made of green cheese.
In symbols, we have
1 S
2 ∼S
3 ∴ M
The formal proof of its validity is almost immediately obvious:
3 S v M 1, Add.
4 M 3,2, D.S.
What is wrong here? How can such a meagre and even inconsistent premises make any argument in
which they occur valid? Note first that if an argument is valid because of an inconsistency in its
premises, it cannot be possibly a sound argument. If premises are inconsistent with each other, they
cannot possibly all be true. No conclusion can be established to be true by an argument with
inconsistent premises, because its premises cannot possibly all be true themselves.
The present situation is closely related to the so-called paradox of material implication. As far as the
latter goes, the statement form ∼p ⊃ (p ⊃ q) is a tautology, having all its substitutions instances true.
Its formulation in English asserts that If a statement is false then it materially implies any statement
whatever, which is easily proved by means of truth tables. What has been established in the present
discussion is that the argument form
p
∼p
∴ q
is valid. We have proved that any argument with inconsistent premises is valid, regardless of what
its conclusion may be. Its validity may be established either by a truth table or by the kind of formal
proof given above.
The premises of a valid argument imply its conclusion not merely in the sense of material
implication, but logically or strictly. In a valid argument, it is logically impossible for the premises
to be true when the conclusion is false. And this situation obtains whenever it is logically
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impossible for the premises to be true, even when the question of the truth or falsehood of the
conclusion is ignored. Its analogy with the corresponding property of material implication has led
some writers on logic to call this a paradox of strict implication. In view of the logician technical
definition of validity, it does not seem to be especially paradoxical. The alleged paradox arises
primarily from treating a technical term as if it were a term of ordinary, everyday language.
The foregoing discussion helps to explain why consistency is so highly prized. One reason, of
course, is that inconsistent statements cannot both be true. This fact underlies the strategy of cross-
examination, in which an attorney may seek to manoeuvre a hostile witness into contradicting
himself. If testimony affirms incompatible or inconsistent assertions, it cannot all be true, and the
witness’s credibility is destroyed or at least shaken. A witness giving contradictory testimony
testifies to some proposition that is false. When it has been once established that a witness has lied
under oath (or is perhaps thoroughly confused) no sworn testimony of that witness can be fully
trusted. Lawyers quote the Latin saying: Falsus in unum, falsus in omnibus; untrustworthy in one
thing, untrustworthy in all.
But another reason why inconsistency is so repugnant is that any and every conclusion follows
logically from inconsistent statements taken as premises. Inconsistent statements are not
meaningless; their trouble is just the opposite. They mean too much. They mean everything, in the
sense of implying everything. And if everything is asserted, half of what is asserted is surely false,
because every statement has a denial.
The preceding discussion incidentally provides us with an answer to the old riddle: What happens
when an irresistible force meets an immovable object? The description involves a contradiction. For
an irresistible force to meet an immovable object, both must exist. There must be an irresistible
force and there must also be an immovable object. But if there is an irresistible force there can be
no immovable object. Here is the contradiction made explicit: There is an immovable object, and
there is no immovable object. Given these inconsistent premises, any conclusion may validly be
inferred. So the correct answer to the question “What happens when an irresistible force an
immovable object?” is Everything!
Although devastating when uncovered within an argument, inconsistency can be highly amusing, as
in the very common saying: That restaurant is so crowded, that nobody goes there any more. And
speaking of the partner in a long and happy marriage: We have a great time together, even when we
are not together.
Such utterances are funny because the contradictions they harbour (and therefore the nonsense of
the remarks when taken literally) appear not to be recognized by their authors. So we chuckle when
we read of the schoolboy who said that the climate of the Australian interior is so bad that the
inhabitants don’t live there any more. Such inadvertent and unrecognized inconsistencies are
sometimes called Irish Bulls.
Sets of propositions that are internally inconsistent cannot all be true, as matter of logic. But human
beings are not always logical and do utter, and sometimes may even believe, two propositions that
contradict one another. This may seem difficult to do, but we are told Lewis Caroll, a very reliable
authority in such matters, that the White Queen in Alice in Wonderland made a regular practice of
believing six impossible things before breakfast!
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LECTURE 5: Inductive arguments: Strength and cogency
However, there is a major drawback to all deductive arguments. You cannot get any more out of the
conclusion than is present in the premises. But when we want to enlarge our knowledge of the
world – especially when we engage in empirical investigation, as natural scientists do – deductive
arguments are not sufficient, because we want to go beyond the premises we begin with. In the vast
majority of arguments one finds in the natural sciences and in such social sciences as psychology,
geography, history, linguistics, and anthropology, the reasons lend weight to the conclusion without
demonstrating conclusively the truth of those conclusions. These arguments are called inductive
arguments.
If the argument is such that true premises would make the conclusion highly probable, then we say
that the argument is a strong argument.
For example, in a murder trial the mere fact that the suspect own a gun of the same calibre as that
which killed the victim adds very little weight to the conclusion that the suspect is the murderer.
The prosecutor’s case would be greatly strengthened if it could be shown that the bullet which
killed the victim was fired from the suspect’s own gun. This, too, would hardly be convincing
without additional evidence, as for example, that the suspect had a motive for killing the deceased,
had threatened the victim, was seen by eyewitnesses in the vicinity of the murder immediately
before and after the fatal shots were fired, and so forth. In spite of the accumulation of evidence, the
argument against the suspect still is not conclusive, since it is possible for all this to be true even
though the victim was shot by someone else who was trying to frame the suspect.
A strong argument that actually have true premises is a cogent argument. A cogent argument does
not absolutely guarantee the conclusion (as does a sound argument), but it does give us good
reasons for believing the conclusion. The author does not claim that the conclusion necessarily
follows from the premises but claims merely that the premises make the conclusion highly
probable.
For instance, if we say that every horse that has ever been observed has had a heart, we reach the
cogent conclusion that every horse has a heart.
Induction and Mill’s method
In the preceding lectures we have dealt with deductive arguments, which are valid if their premises
establish their conclusions demonstratively, but invalid otherwise. There are very many good and
important arguments, however, whose conclusions cannot be proved with certainty. Many causal
connections in which we rightly place confidence can be established only with probability – though
the degree of probability may be very high. Thus we can say without reservation that smoking is a
cause of cancer, but we cannot ascribe to that knowledge the kind of certainty that we ascribe to our
knowledge that the conclusion of a valid deductive argument is entailed by its premises. Deductive
certainty is, indeed, too high a standard to impose when evaluating our knowledge of facts about the
world.
Of all inductive arguments there is one type that is most commonly used: argument by analogy.
An analogy is a likeness or comparison; we draw an analogy when we indicate one or more respects
in which two or more entities are similar. An argument by analogy is an argument in which the
similarity of two or more entities in one or more respects is used as the premis(es); its
conclusion is that those entities are similar in some further respect. Not all analogies are used
for the purposes of argument; they also may serve some literary effect, or for purposes of
explanation. Because analogical arguments are inductive, not deductive, the terms validity and
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invalidity do not apply to them. The conclusion of an analogical argument, like the conclusion of
every inductive argument, has some degree of probability, but it is not claimed to be certain.
There are some 6 criteria used in determining whether the premises of an analogical argument
render its conclusion more or less probable. These are:
1 The number of entities between which the analogy is said to hold.
2 The variety, or degree of dissimilarity, among those entities or instances mentioned only in the
premises.
3 The number of respects in which the entities involved are said to be analogous.
4 The relevance of the respects mentioned in the premises to the further respect mentioned in the
conclusion.
5 The number and importance of non-analogies between the instances mentioned only in the
premises and the instance mentioned in the conclusion.
6 The modesty (or boldness) of the conclusion relative to the premises.
Refutation by logical analogy is an effective method of refuting both inductive and deductive
arguments. To show that a given argument is mistaken, one may present another obviously
mistaken argument that is very similar in form to the argument under attack.
Causal connections
To exercise any measure of control over our environment, we must have some knowledge of causal
connections. To cure some disease, for example, physicians must know its cause, and they should
understand the effects (including the side effects) of the drugs they administer. The relation of cause
and effect is of the deepest importance – understanding it, however, is complicated by the fact that
there are several different meanings of the word cause.
By cause we sometimes mean a necessary condition; sometimes a sufficient condition; sometimes a
condition that is both necessary and sufficient; and sometimes something that is a contributory
factor. Compare, for instance, the following claims:
1 C is a necessary condition, or necessary cause, for E. Without C, E will not happen; E ⊃ C.
2 C is a sufficient condition, or sufficient cause, for E. Given C, E is bound to happen; C ⊃ E.
3 C is a necessary and sufficient condition, or sufficient cause, for E. Without C, E will not happen
and given C, E is bound to happen. Bi-conditional: (E ⊃ C) ∙ (C ⊃ E).
4 C is a contributory cause of E. (C is one of several factors that, together, produce E.)
These claims are different from each other in important ways. Claims (a), (b), and (c) make the
clearest assertion from a logical point of view. Often, however, it is causal factors (d) that we are
trying to discover. Both in ordinary speech and in scientific research, we often speak of a
contributory factor, as in (d) as the cause. If we were using language strictly, such a claim would be
an oversimplification. Consider, for instance, the much discussed claim that high cholesterol in the
blood causes heart disease. High cholesterol may be one contributory factor to the development of
heart disease but there are many other contributory factors, including genetic inheritance, fitness
level, and diet.
When we read reports in the media and elsewhere of the results of scientific studies, it is important
to check to see whether a causal claim is made. Causal claims are not always stated using the words
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cause and effect. Many other words and expressions are used in stating causal claims, Here are
some of them:
A produced B
A was responsible for B
A brought about B
A led to B
A was the factor behind B
A created B
A affected B
A influenced B
B was the result of (or resulted from) A
As a result of A, B occurred
B was determined by A
A was a determinant of B
B was induced by A
B was the effect of A
B was an effect of A
When we evaluate inductive arguments, it is crucially important to see whether a causal claim is
made. Causal claims require a different justification from inductive generalizations; in addition they
have different implications for action.
Mill’s Methods
The nineteenth-century philosopher John Stuart Mill proposed methods for discovering causal
relationships. Of Mill’s methods, I will briefly describe three: the Method of Agreement, the
Method of Difference, and the Joint Method of Agreement and Difference. As we shall see, Mill’s
methods have some limitations. However, they are still useful in some circumstances.
The method of Agreement
To see how this works, suppose that a group of ten friends visit a restaurant and have a nice diner.
Afterward five of them develop acute stomach pains. They were all in the restaurant together;
investigating to find the cause, they begin by operating from the assumption that the stomach pain
resulted from what they ate in the restaurant. They ate in the same restaurant, but they did not all eat
the same thing. To use Mill’s method of agreement to explore this topic, they would list what each
person ate and then check to see whether there was one food eaten by all the people who suffered
from stomach pains. If there were, they would tentatively infer a causal hypothesis: that item was
the cause of the stomach pains. In this case, the cause would be a sufficient condition (given the
background circumstances) of having the stomach pains.
Suppose that Paul, John, Mary, Sue, and David were the ones who became ill, that they ate different
main dishes and different desserts, but they all had Caesar salad with a sharp cheese dressing. Given
this evidence, there is reason to suspect that the salad or the sharp cheese dressing caused their
illness.
It is worth noting that the exploration need not stop at this point. The method of agreement can be
used to explore the matter further. For example, did other patrons who consumed this dressing
suffer stomach pains? If the group were to discover that thirty-five others ate the sharp cheese
dressing, and of these only ten experienced ill effects, that would be evidence against their causal
hypothesis that the dressing caused the stomach pains. (Perhaps sharp cheese dressing, in
conjunction with some other factor or factors, caused the discomfort. Such hypotheses could also be
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explored using Mill’s methods.) The investigating patrons could use the method of agreement again
with the broader group of fifteen people to try to discover the cause by finding out what, if
anything, all these people had in common relative to their illness.
The method of difference
As we might expect from its name, in the method of difference we are looking for the factor that
makes the difference. Suppose that 100 people are exposed to Disease D and of them, only three
catch it. Following the method of difference, we would seek what feature differentiates these three
people from the others. If we could find a property that they shared, and that none of the other
people possessed, we would have ground for the causal hypothesis that the shared characteristic
made the difference in catching Disease D. If, for instance, these three people, and only they, had
scarlet fever as children, we would tentatively form the hypothesis that having had scarlet fever
made them more vulnerable, and that this was a cause (in the sense of necessary condition) of
getting Disease D.
The joint method of agreement and difference
This method consists of using the method of agreement and the method of difference together. If an
aspect, x, is common in all examined cases in which y does not occur, then we have some reason to
suspect that x is the cause of y. The application of the Joint method supports the conclusion that x is
a necessary and sufficient condition of y. That is to say,
(y ⊃ x) ∙ (x ⊃ y).
Mill’s methods presuppose that there is a cause to be found, and that we have enough knowledge to
know what sorts of factors to look for. Using these methods, we arrive at causal hypotheses. There
are some pitfalls in the method. An obvious one is that we may have made a faulty assumption
when we identified the factors to examine, (Our list of possible factors may have been too short.) In
the case of the sharp cheese dressing, for example, it is not hard to imagine various ways in which
the causal inference might have gone wrong. The overall assumption that the cause must have been
something in the food might be mistaken. Paul, John, Mary, Sue, and David might have all been
exposed on a previous day to a certain flu bug, and the stomach pain might have been part of that
flu. By concentrating their attention on what was eaten at the restaurant, the friends would miss this
factor and reach a faulty causal conclusion. This is not to say that Mill’s methods are useless – only
that they have to be applied with care. We must remember that our results are only as good as the
assumptions used in formulating the problem, and second, that the conclusion is a causal
hypothesis.
The inductive method
The inductive approach to knowledge is based on the impartial gathering of evidence or the setting
up of appropriate experiments, such that the resulting information can be examined and conclusions
drawn from it. It assumes that the person examining it will come with an open mind and that
theories framed as a result of that examination will then be checked against new evidence.
In practice, the method works like this:
1 Evidence is gathered, and irrelevant factors are eliminated as far as possible;
2 Conclusions are drawn from that evidence, which lead to the framing of a hypothesis;
3 Experiments are devised to test out the hypothesis, by seeing if it can correctly predict the results
of those experiments;
4 If necessary, the hypothesis is modified to take into account the results of those later experiments;
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5 A general theory is framed from the hypothesis and related experimental data;
6 That theory is then used to make predictions, on the basis of which it can be either confirmed or
disproved.
It is clear that this process can yield no more than a very high degree of probability. There is always
going to be the chance that some new evidence will show that the original hypothesis, upon which a
theory is based, was wrong. Most likely, it is shown that the theory only applies within a limited
field and that in some unusual sets of circumstances it breaks down. Even if it is never disproved, or
shown to be limited in this way, a scientific theory that has been developed using this inductive
method is always going to be open to the possibility of being proved wrong. Without that
possibility, it is not scientific.
Example
The final step in this process (i.e., the theory used to make predictions confirming or disproving its
validity) is well illustrated by the key prediction that confirmed Einstein’s general theory of general
relativity. Einstein argued that light would bend within a strong gravitational field and therefore that
stars would appear to shift their relative positions when the light from them passed close to the Sun.
This was a remarkably bold prediction to make. It could only be tested by observing the stars very
close to the edge of the Sun as it passed across the sky and comparing this with their position
relative to other stars once the light coming from them was no longer affected by the Sun’s
gravitational pull. But the only time they could be observed so close to the Sun was during an
eclipse. Teams of observers went to Africa and South America to observe an eclipse in 1919. The
stars did indeed appear to shift their positions to a degree very close to Einstein’s predictions, thus
confirming the theory of general relativity.
Scientific laws
With the development of modern science, the experimental method led to the framing of laws of
nature. It is important to recognize exactly what is meant by law in this case. A law of nature (in the
scientific sense) does not have to be obeyed. A scientific law cannot dictate how things should be, it
simply describes them. The law of gravity does not require that, having tripped up, I should adopt a
prone position on the pavement – it simply describes the phenomenon that, having tripped, I fall.
Hence, if I trip and float upward, I am not disobeying a law, it simply means that I am in an
environment (e.g. in orbit) in which the phenomenon described by the law of gravity does not
apply. The law cannot be broken in these circumstances, only be found to be inadequate to describe
what is happening.
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LECTURE 6: Logical Fallacies
Logical fallacies: Fallacies of relevance
A logical fallacy is an argument that contains a mistake in reasoning. Fallacies can be divided in
two broad groups: fallacies of relevance and fallacies of insufficient evidence. Fallacies of
relevance are argument in which the premises are logically irrelevant to the conclusion. Fallacies of
insufficient evidence are arguments in which the premises, though logically relevant to the
conclusion, fail to provide sufficient evidence for the conclusion. During this lecture we will
discuss fallacies of relevance. We will discuss fallacies of insufficient evidence in the next lecture.
The concept of relevance
A statement is relevant to another if it provides at least some evidence or reason for thinking that
the second statement is true or false. There are three ways in which a statement can be relevant or
irrelevant to another. A statement can be positively relevant, negatively relevant, or logically
irrelevant to another statement. A statement is positively relevant to another statement if it provides
at least some reason for thinking that the second statement is true.
A statement is positively relevant to another statement if it counts in favour of that statement.
Here are several examples:
First argument: Dogs are cats. Cats are feline. So dogs are felines.
Second argument: All dogs have five legs. Rick is a dog. So Rick has five legs.
Third argument: Most Penn State Univ. students are resident of Pennsylvania. Marc is a Penn State
Univ. student. So, Mark is probably a resident of Pennsylvania.
Fourth argument: Carole is a woman. Therefore, Carole enjoys knitting.
Each of these premises is positively relevant to its conclusion. That is, each provides at least some
evidence or reason for thinking that the conclusion is true. In the first and second argument, the
premises provide logically conclusive reasons for accepting the conclusion. In the fourth argument,
the premise - Carole is a woman - provides neither probable nor conclusive reasons for accepting
the conclusion – Carole enjoys knitting. However, the premise does make the conclusion slightly
more probable than it would be if the conclusion were considered independently of that premise.
Thus, premise does provide some evidence for the conclusion, and hence is positively relevant to it.
These examples highlight two important lessons about the concept of relevance. First, a statement
can be relevant to another statement even if the first statement is completely false. Thus, in the first
example, the statement “Dogs are cats” is clearly false. Nevertheless, it is relevant to the statement
“Dogs are felines” because if it were true, then the latter statement would have to be true as well.
Second whether a statement is relevant to another usually depends on the context in which the
statements are made. Thus, in the second example, the statement “All dogs have five legs” is
positively relevant to the statement “Rick has five legs” only because it is conjoined with the
statement “Rick is a dog.”
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Statements that count against other statements are said to be negatively relevant to those
statements.
Here are some examples:
Joe is an uncle. Therefore, Joe is a female.
Althea is two years old. Thus, Althea probably goes to college.
Mark is a staunch Republican. Therefore, Mark probably favours higher taxes.
In each of these examples, the premises are negatively relevant to the conclusion. Each premise, if
true, makes the conclusion at least somewhat less likely.
Statements can be logically irrelevant to other statements. A statement is logically irrelevant to
another statement if it counts neither for nor against that statement.
Here are some examples:
Last night I dreamed that Germany will win the next World Cup. Therefore, Germany will win the
next World Cup.
The earth revolves around the sun. Therefore, marijuana should be legalized.
Julie is ugly. Therefore, Julie should not be allowed to board the train.
None of these premises provides even the slightest reason for thinking that their conclusions are
either true or false. Thus, they are logically irrelevant to those conclusions.
Fallacies of relevance
A fallacy of relevance occurs when an arguer offers reasons that are logically irrelevant to his or her
conclusion. Like most popular fallacies, fallacies of relevance often seem to be good arguments but
are not.
There are some 11 common fallacies of relevance:
1 Personal attack (ad hominem): The rejection of a person’s argument or claim by means of an
attack on the person’s character rather than the person’s argument or claim.
Professor Platter has argued against the theory of evolution. But Platter is a heavy drinker and an
egoist who has never given a single penny to charity in all his life. I absolutely refuse to listen to
him.
2 Attacking the motive: Criticizing a person’s motivation for offering a particular argument or
claim, rather than examining the worth of the argument or claim itself.
Mr. Platter has argued that we need to build a new middle school. But Mr. Platter is the owner of
Platter’s Construction Company. He will make a fortune if his company is picked to build the new
school. Obviously, Platter’s argument is a lot of self-serving baloney.
3 Look who is talking (tu quoque): The rejection of another person’s argument or claim because
that person is a hypocrite.
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My opponent has accused me of running a negative political campaign. But my opponent has run a
much more negative campaign than I have. Just last week he has accused me of graft, perjury and
all sort of other wrong doings.
4 Two wrongs make a right: Attempting to justify a wrongful act by claiming that some other act is
just as bad or worse.
I admit we plied Olympic officials with booze, free ski vacations, and millions of dollars in outright
bribes in order to be selected as the site of the next winter Olympics. But everybody does it. That’s
the way the process works. Therefore, paying those bribes was not really wrong.
5 Appeal to force: Threatening to harm a reader or listener, when the threat is irrelevant to the truth
of the arguer’s conclusion.
I am telling you the truth and if you do not believe I will call my big brother who will teach you a
lesson.
6 Appeal to pity: Attempting to evoke feelings of pity or compassion, when such feelings, however
understandable, are not relevant to the truth of the arguer’s conclusion.
Officer, I know I was going too fast. But I do not deserve a speeding ticket. I have had a really bad
day. My mother is sick in hospital and my father had a heart attack at hearing the news. Today, I
have also been fired from my job, and I have no money left in the bank to pay the bills.
7 Bandwagon argument: An appeal to a person’s desire to be popular, accepted, or valued rather
than to logically relevant reasons or evidence.
All the popular, cool kids wear Mohawk haircuts. Therefore, you should, too.
8 Straw man: The misrepresentation of another person’s position in order to make that position
easier to attack.
Professor Platter has argued that the Bible should not be read literally. Obviously, Platter believes
that any reading of the Bible is as good as any other. But this would mean that there is no
difference between a true interpretation of Scripture and a false interpretation. Such a view is
absurd.
9 Red herring: An attempt to sidetrack an audience by raising an irrelevant issue and then claiming
that the original issues has been effectively settled by the irrelevant diversion.
Frank has argued that Volvos are safer cars than Ford Mustang convertibles. But they are clunky,
boxlike cars, whereas Mustang convertibles are sleek, powerful, and sexy. Clearly, Frank does not
know what he is talking about.
10 Equivocation: The use of a key word in an argument in two or (or more) different senses.
In the summer 1940, Londoners were bombed almost every night. To be bombed is to be
intoxicated. Therefore, in the summer 1940, Londoners were intoxicated almost every night.
27
11 Begging the question: Stating or assuming as a premise the very thing one is seeking to prove as
a conclusion.
I am entitled to say whatever I choose, because I have a right to say whatever I please.
Logical fallacies: Fallacies of insufficient evidence
In the last lecture we looked at fallacies of relevance, fallacies that occur when the premises are
logically irrelevant to the truth of the conclusion. Fallacies of insufficient evidence are fallacies in
which the premises, though relevant to the conclusion, fail to provide sufficient evidence for the
conclusion.
There are some nine common fallacies of insufficient evidence:
1 Inappropriate appeal to authority: Citing a witness or an authority that is untrustworthy.
My hairdresser told me that the extraterrestrials built the lost city of Atlantis. So, it is reasonable to
believe that extraterrestrial did build the lost city of Atlantis.
2 Appeal to ignorance: Claiming that something is true because no one has proven it false, or vice
versa.
Bigfoot must exist. No one has proved that it does not.
3 False alternatives: Posing a false either/or choice.
The choice in this election is clear. Either we elect a staunch conservative as our next president, or
we watch our country slides into anarchy and economic depression. Clearly, we don’t want our
country to slide into anarchy and economic depression. Therefore, we should elect a staunch
conservative as our next president.
4 Loaded question: Posing a question that contains an unfair or unwarranted presupposition.
Are you still dating that total loser Phil?
Yes.
Well, at least you admit he is a total loser.
5 Questionable cause: Claiming, without sufficient evidence, that one thing is the cause of
something else.
Two days after I drank lemon tea, my head cold cleared up completely. Try it. It works.
6 Hasty generalization: Drawing a general conclusion from a sample that is biased or too small.
BMWs are a pile of junk. I have two friends who drive BMWs, and both of them have had nothing
but trouble from those cars.
7 Slippery slope: Claiming, without sufficient evidence, that a seemingly harmless action, if taken,
will lead to a disastrous outcome.
28
Immediate steps should be taken to reduce violence in children’s television programming. If this
violent programming is allowed to continue, this will almost certainly lead to fights and acts of
bulling in school playgrounds. This in turn will lead to an increase in juvenile delinquency and gang
violence. Eventually, our entire society will become engulfed in an orgy of lawlessness and
brutality.
8 Weak analogy: Comparing things that are not really comparable.
Nobody would buy a car without first taking it for a test drive. Why then should you not taste what
is inside a box before buying a product?
9 Inconsistency: Asserting inconsistent premises, asserting a premise that is inconsistent with the
conclusion, or arguing for inconsistent conclusions.
Note found in a Forest Service suggestion box: Park visitors need to know how important it is to
keep this wilderness area completely pristine and undisturbed. So why not put a few signs to remind
people of this fact?
29
LECTURE 10: Philosophy of religion
The Concise Oxford Dictionary defines religion as “the belief in a superhuman controlling power,
especially in a personal God or gods entitled to obedience and worship.” This is a loose definition
that encompasses many beliefs and worship.
Our book provides an examination of some philosophical issues concerning religion from a
Western perspective. Muslim contend that Islam is not a religion; it is a way of life. Similarly
Taoism is considered by many not to be a religion but “The Way.” Buddhism, which does not serve
a God, believes in “The Path.” Nevertheless, it would seem that whatever name or designation is
given to a particular faith or belief, the needs of the adherents do not differ; in that, there is
universal agreement. It can be described as the need and the search for the holy and/or the infinite,
God, the meaning of life, etc.
The study of religion
Most scholars agree that the nineteenth century was the formative period when the study of modern
religions got under way. Many disciplines were involved, including the philological sciences,
literary criticism, psychology, anthropology, and sociology.
Questions immediately come up that go beyond the recorded facts. What, for example, is the
religious experience and how is it exhibited? What are the principles at work in the various
religions? Are there laws in place in the religions, and how do they affect the adherents? In
addition, there were the questions of truth or falsity, and the reliability of the recorded history of
each religion. In short, it would be fair to say that the whole subject was fraught with controversy.
Classifying religions
The whole issue of true and false religions and a classification that demonstrated the claims of each
led to the necessity to defend one religion against another. Unfortunately, this type of classification,
which is arbitrary and subjective, continues to exist.
For example, in the sixteenth century, Martin Luther, the great Protestant Reformer, went so far as
to label Muslims, Jews, and Roman Catholic Christians to be false. He held that the gospel of
Christianity understood from the viewpoint of justification by grace through faith was the true
standard. Another example would be Islam, in which religions are classified into three groups: the
wholly true, the partially true, and the wholly false. That classification is based in the Qur’an
(Koran, the Islamic sacred scripture) and is an integral part of Islamic teaching. It also has legal
implications for the Muslim treatment of followers of other religions.
Of course, such classifications express an implied judgment , not only on Protestants, Jews, Roman
Catholics, and Muslims, but all religions. This judgemental nature arises from the loyalties that
exist in every society and religious culture. It is human nature for people to defend their own
“tribe,” and by association decry other “tribes.”
In the field of psychology, it is stated that in the religious person, emotions such as wonder, awe,
and reverence are exhibited. Religious people tend to show concern for values – moral and aesthetic
– and to seek out actions that have these values. They will be likely to characterize behaviour not
only as good or evil but also as holy or unholy, and people as virtuous or un-virtuous, even godly or
ungodly.
30
The Greek philosopher Plato saw that in performing every good act, humans realize their link with
eternity and the idea of goodness. He likened the human condition to the image of a man in a cave,
chained by his earthly existence so that he cannot see the light outside, only the shadows on the
wall. In order to see the light, man has to throw off his chains and leave the cave.
The future of religion
There is a universality contained in the answers, from whichever source one goes to, to the
question, “what is the future of religion?” In essence, the respondents advised that a considerable
increase of mutual understanding around the world needs to come about – an understanding that the
earth is occupied by a vast number of people with an equally vast number of beliefs, and respect
should be paid to all. The philosophy of the Golden Rule is implicit in virtually every religion.
It is well known that in times of trouble, either personal, national, or international, that the number
of people who embrace a religion increases. It could, therefore, be said that as trouble isn’t going to
go away, neither is religion. Both are here to stay.
31
LECTURES 11 and 12: Philosophy of ethics
Ethics, our concern, deals with what is right or wrong in human behaviour and conduct. It asks such
questions as what constitutes any person or action being good, bad, right, or wrong, and how do we
know (epistemology)? What part does self-interest or the interest of others play in the making of
moral decisions and judgements? What theories of conduct are valid or invalid, and why? Should
we use principles or rules or laws, or should we let each situation decide our morality? Are killing,
lying, cheating, stealing, and sexual acts right or wrong, and why or why not?
The word itself ethics comes from the Greek ethos, meaning character. Morality comes from the
Latin moralis, meaning customs or manners. Ethics, then, seems to pertain to the individual
character of a person or persons, whereas morality seems to point to the relationships between
human beings. Nevertheless, in ordinary language, whether we call a person ethical or moral, or an
act unethical or immoral, does not really make any difference. In philosophy, however, the term
ethics also is used to refer to a specific area of study: the area of morality, which concentrates on
human conduct and human values.
When we speak of people as being moral or ethical, we usually mean that they are good people, and
when we speak of them as being immoral or unethical, we mean that they are bad people. When we
refer to certain human actions as being moral, ethical, immoral, and unethical, we mean that they
are right or wrong. The simplicity of these definitions, however, ends here, for how do we define a
right or wrong action or a good or bad person? What are the human standards by which such
decisions can be made? These are the more difficult questions that make up the greater part of the
study of morality. One important thing to remember here is that moral, ethical, immoral, and
unethical, essentially mean good, right, bad, and wrong, often depending upon whether one is
referring to people themselves or to their actions.
Approaches to ethics and morality
Scientific, or descriptive approach
There are two major approaches to the study of ethics and morality. The first is scientific, or
descriptive. This approach most often is used in the social sciences and, like ethics, deals with
human behaviour and conduct. The emphasis here, however, is empirical; that is, social scientists
observe and collect data about human behaviour and conduct and then draw certain conclusions.
For example, some psychologists, after having observed many human beings in many situations,
have reached the conclusion that human beings act in their own self-interest. This is a descriptive,
or scientific, approach to human behaviour – the psychologists have observed how human beings
act in many situations, described what they have observed, and drawn conclusions. However, they
make no value judgements as to what is morally right or wrong, nor do they describe how humans
ought to behave.
Philosophical approach
The second major approach is called the philosophical approach, and consists of two parts.
32
The first part of the philosophical approach to the study of ethics is called metaethics or, sometimes,
analytic ethics. Rather than being descriptive or prescriptive, this approach is analytic in that it
analyzes ethical language (for example, what we mean when we use the word good), the rational
foundations of ethical systems and the logic and reasoning of various ethicists. Like metaphysics,
metaethics refers to areas not directly related but somehow beyond (meta) the main subject-matter.
Metaethicists do not prescribe anything, nor do they deal directly with normative systems. This
means that metaethics has little to do with the real business of ethics, which is concerned with the
ancient question “What is the good life?, or “What is the good?” or, in more modern terms, “How
should I live my life?”, or “How should I solve this moral dilemma? Because it concerns only
indirectly with normative ethical systems by concentrating instead on reasoning, logical structures,
and language rather than content, it gives no answer to any of the above questions.
In methaethics, a different set of questions are asked: questions about the nature of ethical thinking
and ethical language; about what is meant by such things as free will, and whether we can be said to
possess it; about what is meant by term such as “relative” and “absolute; and so on. Metaethics
questions whether we can legitimately speak of objective ethical truth, or whether ethical
convictions are merely the expressions of the individual’s inner feelings. The latter is called
emotivism, which is the view that ethical convictions can only be expressed in terms of one’s
feelings or attitudes, but cannot possibly be explained or justified. The former is called intuitionism
because it holds that ethical convictions can be directly intuited, sensed or grasped, but again not
explained. However, unlike emotivism, intuitionism at least opens the debate about what in the
objective world makes us intuit goodness and evil, right and wrong.
It should be noted here that metaethics, although always used to some extent by all ethicists, has
become the sole interest of many modern ethical philosophers. This may be due in part to the
increasing difficulty of formulating a system of ethics applicable to all or even most human beings.
Our world, our cultures, and our lives have become more and more complicated and pluralistic, and
finding an ethical system that will undergird all human beings’ actions is a difficult if not
impossible task. Therefore, these philosophers feel that they might as well do what other specialists
have done and concentrate on language and logic rather than attempt to arrive at ethical systems
that will help human beings live together more meaningfully and ethically.
The second part of the philosophical approach to the study of ethics deals with norms (or standards)
and prescriptions. For this reason, it is called normative, or prescriptive, or substantive ethics.
Normative ethics attempts to answer the fundamental practical questions of ethics and is the main
concern of this philosophy course. The ethical theories that attempt to answer the questions of
“What we ought to do”, and “How we ought to live” and make up the more abstract part of what is
known as normative ethics – that is, the part of ethics concerned with guiding action will be
discussed in the following lectures.
The theories with which we will be dealing are:
Ethical relativism in its two versions, i.e., subjective and conventional ethical relativism;
Ethical objectivism in its many forms such as Ethical egoism, Utilitarianism, Kantian ethics, Virtue
ethics. The application of ethical reasoning to specific areas of practical concern, i.e. applied ethics
can be seen as the more practical counterpart or application of some of the theories of normative
ethics. Areas of practical concern are for example: Euthanasia, Abortion, Punishment,
Environmental ethics, etc.
The origins of ethics
One further consideration about the organization of this course. Before dealing with subjective
ethical relativism, I begin with reading Plato’s dialogue called the Crito in which two famous
33
ancient Athenians Crito and Socrates are engaged in a moral argument about what is the right
course of action in a particular situation. In 399 B.C., Socrates was brought to trial on a charge of
corrupting the young and introducing new divinities. He was found guilty and sentenced to death.
The moral issue discussed in this dialogue is whether should Socrates accept the help and advise of
his friend Crito and escape from jail. The two friends discuss what is the right course of action from
a moral point of view.
Why to choose such a remote starting-point for an introductory course of ethics?
Because Socrates’ arguments for not escaping have inspired much of Western ethical thought and
Plato’s dialogue the Crito is a classical example of ethical thinking and one of the earliest surviving
treatises on philosophical ethics. There is a compelling reason for starting with a Greek writer.
Ethics itself, as a form of intellectual enquiry, at least in the West, begins with the Greeks. In the
thought of the Greek philosophers we can trace the beginnings of philosophical reflection on the
nature of the good life and right conduct. The core of the ethical systems of both Plato and
Aristotle is the attempt to justify the virtues in terms of human happiness, to show that they are
good qualities to possess, because a life lived in accordance with the virtues is the happiest and
most rewarding kind of life.
Questions to be answered:
(1) Identify Crito’s arguments and Socrates’ counter-arguments;
(2) Identify the major principles held by each of the two;
(3) Decide how valid their arguments are;
(4) Decide whether Socrates took the right decision;
(5) Tell what you would have done had you been in his position explaining the reasons for your
choice.
The main ethical theories
Premises. I will start today’s lecture from a general but fundamental premise: It is important
that all customs, traditions, systems of ethics, rules, and of course ethical theories, our main
concern today, should be carefully analyzed and critically evaluated before we continue to
accept or live by them. That is to say, we should not reject them out of hand, but neither should
we endorse them wholeheartedly, unless we have subjected them to careful, logical scrutiny.
For this reason, throughout this course and most importantly on your own in your own life, you
are strongly encouraged to be reflective when dealing with morality and moral issues.
But before going on to discuss the main ethical theories, there is another matter that I think it
ought to be clarified preliminarily. It is important that we use reflection to distinguish morality
from another area of human activity and experience with which it is often confused and of
which it is often considered a part: religion.
Because normative ethics seeks to establish principles that prescribe what we ought or ought not
to do, it has in fact some similarities with another of the domains of human existence that seek
to guide behaviour, i.e., religion. And in fact, many people think that religion and ethics not
overlap but that they are inseparable. Furthermore, it is a historical fact that religion is deeply
bound up with morality. It would be hard, if not impossible, to find an established religious
tradition that does not contain extensive ethical teachings. In fact, some of the great religions of
the world, such as Buddhism and Confucianism, are primarily ethical outlooks on life rather
than doctrines about a deity.
34
However, many philosophers (even religious ones) think that a sound ethical theory can be
developed independently of religious assumptions. Furthermore, they argue that there are
problems with divine command theories, i.e., with theories making the rightness or wrongness
of an action intrinsically related to the fact that God either commands it or forbids it. The first
problem is the lack of agreement as to which religious text or authority should guide our ethical
deliberations: The Bible, for example, or the Koran, The Hindu Upanishads, Buddha’s
teachings, and so on. To successfully live together in the same society, we need to arrive at
some common ethical norms. But how can we do this in pluralistic societies where there is no
agreement as to which religious authority (if any) should be followed? Furthermore, how can
people be held ethically accountable for their behaviour if many have never been exposed to
whatever religious tradition is supposed to be normative? The second problem is that even if we
agree to live under the guidance of a particular religious tradition, we may disagree as to how to
interpret its teachings. For example, Christians both defend and attack capital punishment on the
basis of the same tradition and sacred texts. Similarly, while the Bible often condemns lying, it
contains passages in which God is said to reward people for lying on his behalf and even
commands individuals to lie. [Note: For Biblical approval of specific acts of lying, see Exodus
1:15-20 and Joshua 2:1-6 (in conjunction with Hebrews 11:31). For divinely commanded lying,
see 1 Samuel 16:1-3.] Minimally, some sort of philosophical reflection is necessary to sort out
all these discrepancies. Third, some ethical questions cannot be answered by traditional
religious teachings apart from philosophical considerations. Is it morally acceptable to make
cloned duplicates of humans? When numerous people need an organ transplant or a kidney
dialysis machine but the medical supplies are scarce, what is the just way to allocate these
resources? To what extent do journalists have an obligation to serve the public’s right to know
and to what extent do they have an obligation to protect individual’s privacy? Most religious
traditions are clear on ethical topics such as adultery, murder, and stealing, but many ethical
dilemmas in contemporary society are not addressed by these traditions.
These considerations suggest that whatever ethical guidance someone may find in a particular
religious tradition, everyone need to engage in philosophical reflection on ethics based on
human experience and reason and not merely on authority or tradition.
The main ethical theories
I. Ethical relativism is the position that there are no objective or universally valid moral
principles, for all moral judgments are simply a matter of human opinion. This position comes
in two versions:
(a) Subjective ethical relativism the doctrine that what is right or wrong is solely a matter of
each individual’s personal opinion. Just as some people like the colour purple and some detest
it, and each person’s judgement on this matter is simply a matter if his individual taste, so there
is no standard other than each person’s own opinion when it comes to right or wrong. This
doctrine implies that it is impossible for an individual to be mistaken about what is right or
wrong.
(b) Conventional ethical relativism (conventionalism) refers to the claims that morality is
relative to each particular society or culture. For example, whether it is moral for women to
wear shorts is a question of whether you are talking about mainstream American society or the
Iranian culture. In other words, there are no universal objective moral standards that can be used
to evaluate the ethical opinions and practices of a particular culture. This doctrine implies that it
is impossible for a society to be mistaken about what is right or wrong.
Questions:
35
- Do you believe that the fact that people disagree about what is good or right is a good reason
to support ethical relativism?
- In what ways do you think that science is different from ethics? Are they alike in any ways?
For example, do they both involve being impartial and nonbiased?
- Is there an objective good, do you think that it is likely to be unitary or plural? For example, is
it likely that all morality will be a function of the promotion of one ultimate good, such as
happiness? Or is it more likely that there are many moral values, such as happiness, autonomy,
privacy, and fidelity, which are each equally good and not reducible to the others?
- Suppose that no matter how long reasonable people continued their deliberations, they would
converge only on some principles, but not all. What would follow about the nature of moral
objectivity, defined in terms of reasonableness? Does what follows constitute a problem for the
account of objectivity? Can you propose a better account?
II. Ethical objectivism is the view that there are universal and objectively valid moral
principles that are relative neither to the individual nor to society. Because objectivism is a very
general doctrine that covers a wide range of more specific ethical theories, various objectivists
will differ as to what the correct moral principles are and how we can know them. Nevertheless,
they all agree that in every concrete situation there are morally correct and morally wrong ways
to act. Furthermore, they would agree that if a certain action in a given situation is morally right
or wrong for a particular person, then it will be the same for anyone who is relevantly similar
and facing relevantly similar circumstances. Ethical objectivism implies that it is possible for an
individual or an entire society to sincerely believe that their actions are morally right at the same
time that they are deeply mistaken about this assumption.
The next eight theories all fall under the heading of ethical objectivism. Although these theories
disagree about what ethical principles should be followed, they all agree that there are one or
more non-arbitrary, non-subjective, universal moral principles that determine whether an action
is right or wrong.
36
Schedule of readings and assignments (some changes are possible during the course):
(1) Introduction: What is philosophy? Reading: Fundamentals of Philosophy, “Socrates: In
Defence of Philosophy”, pp.17-25.
(2) The basic concepts of logic I: Deductive arguments. Reading: Ibid, pp.56-69.
(3) The basic concepts of logic II: Inductive arguments. Reading: Ibid, pp.70-79. (First
assignment.)
(4) Theory of knowledge: Rationalism, empiricism and Kantian criticism. Reading: “Immanuel
Kant: Two Sources of Knowledge”, Ibid, pp.235-239.
(5) Metaphysics: The search for the ultimate reality. Reading: “Plato: The Visible and the
Invisible”, Ibid, pp.109-119.
(6) The search for God . Reading: “Arguments for God’s Existence: The Ontological
Argument”, Ibid, pp.338-350. (Second assignment)
(7) The search for ethical values. Reading: “Thomas Hobbes: Leviathan”, Ibid, pp.267-280.
(8) The search for the just society. Reading: “John Rawls: A Theory of Justice”, in Ibid.,
pp.477-485.
(9) Philosophy of Art. Reading: “A.C. Bradley: Poetry for Poetry’s Sake”, Ibid., pp.421-430.
(Third assignment)
(10) Philosophy East and West. Reading: Ibid., pp.489-499.
(11) Eastern Thought: Hinduism and Buddhism. Reading: “Setting in Motion the Wheel of
Truth: Dhammacakkappavattana-sutta (The First Sermon of the Buddha)”, Ibid., pp.431-433.
(12) Eastern Thought: Confucianism and Taoism. Reading: “Lao Tzu: The Tao Te Ching”, in
Ibid., pp.548-550. (Final assignment)
Grading Scale:
4=A 3.67=A-
3.33=B+ 3.00=B
2.67=B- 2.33=C+
2.00=C 2.67=C-
1.33=D+ 1.00=D
0.67=D- 0=F
Weight of assignments:
Four assignments will be given, each counting 25%
Assignment 1 (1A) (1B) Due at the end of the third week of the course (The other assignments will
be given during the lectures)
• (1A) 50% (12,5% of final mark)
In about 400 words answer the following question:
What is the practical value of philosophy?
• (1B) 50% (12,5% of final mark)
In about 400 words answer the following question:
Argument and evidence: How do I decide what to believe?
37
Late papers will be lowered one grade for each calendar day (except Saturdays and Sundays) that they are
late.
Class participation
Class participation and attendance are strongly recommended because they are crucial to success in
this course, for this reason not more than 3 absences are allowed (i.e., with 4 absences a student
automatically forfeits the class).
Academic misconduct and plagiarism
Academic misconduct and plagiarism will be dealt with according to the regulations set by the Ohio
University Undergraduate Catalogue 2002-2003.
38

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fund.phil

  • 1. HONG KONG PROGRAMS PHIL 101: FUNDAMENTALS OF PHILOSOPHY (4) (2H) Spring quarter, 2004 (March 22-June 8) David C. Lam Building, HKBU Campus Instructor: Dr. Giuseppe Mario Saccone E-mail: gmsaccon@graduate.hku.hk Tel: 98660230 LECTURE 1: What is philosophy? What is Philosophy? Why should we learn it? What is philosophy? Philosophy can mean different things to different people. Etymologically speaking, philosophy means ‘Love of Wisdom.’ It includes both theory and practise, view and way, end and means, beginning (alpha) and end (omega), or science and art. Its meanings seem to depend on each school of thought. Philosophers, therefore, may be considered as sages, lovers of wisdom, lovers of argument, theorists, practitioners, or even artists. There are various currents of academic philosophy. We can speak of Eastern and Western philosophy. Western philosophy at the moment can be divided into two main kinds: analytic (Anglo-American or English speaking) and continental (European) philosophy. The two kinds of philosophy pay attention to language and being. However, while analytic philosophy mainly deals with truths and knowledge, continental philosophy (primarily) deals with values and life. From these observations, it may be said that analytic philosophy is a close friend of science whereas most school of continental philosophy are close friend of religion. Turning to Eastern philosophy, we may surprisingly discover that all schools of thought believe that reality is a social process. In other words, according to Eastern philosophy, all actual realities are becomings, not beings. Philosophy literally means love of wisdom, the Greek words philia meaning love or friendship, and Sophia meaning wisdom. Philosophy is concerned basically with three areas: epistemology (the study of knowledge), metaphysics (the study of the nature of reality), and ethics (the study of morality). Epistemology deals with the following questions: what is knowledge? What are truth and falsity, and to what do they apply? What is required for someone to actually know something? What is the nature of perception, and how reliable is it? What are logic and logical reasoning, and how can human beings attain them? What is the difference between knowledge and belief? Is there anything as “certain knowledge”? 1
  • 2. Metaphysics is the study of the nature of reality, asking the questions: What exists in reality and what is the nature of what exists? Specifically, such questions as the following are asked: Is there really cause and effect in reality, and if so, how does it work? What is the nature of the physical world, and is there anything other than the physical such as the mental or spiritual? What is the nature of human beings? Is there freedom in reality or is everything predetermined? Ethics deals with what is right or wrong in human behaviour and conduct. It asks such questions as what constitutes any person or action being good, bad, right, or wrong, and how do we know (epistemology)? What part does self-interest or the interest of others play in the making of moral decisions and judgements? What theories of conduct are valid or invalid, and why? Should we use principles or rules or laws, or should we let each situation decide our morality? Are killing, lying, cheating, stealing, and sexual acts right or wrong, and why or why not? Love of wisdom The term philosophy literally means the love of wisdom. It is said that the first one to call himself a philosopher was Pythagoras, a Greek who lived somewhere between 570 and 495 B.C. and spent most of his life in southern Italy. He is, of course, best known for his famous mathematical theorem. When once asked is he was wise, he replied that no one could be wise but a god, but that he was a lover of wisdom. To love something does not mean to possess it but to focus our life on it. Whereas Pythagoras introduced the term philosopher, it was Socrates who made it famous. He said that the philosopher was one who had a passion for wisdom and who was intoxicated by this love. This description makes quite a contrast with the image of the philosopher as being cold and analytical – sort of a walking and talking computer. On the contrary, the cognitive and the emotional are combined in philosophy, for we do not rationally deliberate about those issues in life that are deeply trivial. Those issues that are most important to us are such things as our religious commitments (or lack of them), our moral values, our political commitments, our career, or (perhaps) who we will share our lives with. Such issues as our deepest loves, convictions, and commitments demand our deepest thought and most through rational reflection. Philosophy, in part, is the search for that kind of wisdom that will inform the beliefs and values that enter into these crucial decisions. Socrates’ method If wisdom is the most important goal in life to Socrates, how did he go about pursuing it? Socrates method of doing philosophy was to ask questions. That method was so effective that it has become one of the classic techniques of education; it is known as the Socratic method, or Socratic questioning. Plato referred to the method as dialectic, which comes from a Greek word for conversation. Typically, Socrates’ philosophical conversations go through seven stages as he and his partner continually move toward a greater understanding of the truth: 1 Socrates unpacks the philosophical issues in an everyday conversation. (The genius of Socrates was his ability to find the philosophical issues lurking in even the most mundane of topics.) 2 Socrates isolates a key philosophical term that needs analysis. 3 Socrates professes ignorance and requests the help of his companion. 4 Socrates’ companion proposes a definition of the key term. 5 Socrates analyzes the definition by asking questions that expose its weaknesses. 2
  • 3. 6 The subject produces another definition, one that improves on the earlier one. (This new definition leads back to step 5, and on close examination the new definition is once again found to fail. Steps 5 and 6 are repeated several times.) 7 The subject is made to face his own ignorance. (Finally, the subject realizes he is ignorant and is now ready to begin the search for true wisdom. Often, however, the subject finds some excuse to end the conversation or someone else makes an attempt at a new definition.) Socrates’ hope in utilizing this method was that in weeding out incorrect understandings, he and his conversational partner would be moving toward a clearer picture of the true answer. Since Socrates believed that the truth about the ultimate issues in life lay deeply hidden within us, this process of unpacking the truth within was like that of a midwife helping a mother in labour bring forth her child. One of Socrates’ most skilful techniques for showing the weakness of someone’s position was his use of the reductio ad absurdum form of argument. This term means “reducing to an absurdity.” Socrates would begin by assuming that his opponent’s position is true and then show that it logically implies either an absurdity or a conclusion that contradicts other conclusions held by the opponent. Deducing a false statement from a proposition proves that the original assumption was false. Reductio ad Absurdum Arguments The label of the reduction ad absurdum argument, a valid argument form, means reducing to an absurdity. To use this technique, you begin by assuming that your opponent’s position is true and then you show that it logically implies either an absurd conclusion or one that contradicts itself or that it contradicts other conclusions held by your opponent. Deducing a clearly false statement from a proposition is definitive proof that the original assumption was false and is a way of exposing an inconsistency that is lurking in an opponent’s position. When the reduction ad absurdum argument is done well, it is an effective way to refute a position. 1 Suppose the truth of A (the position that you wish to refute). 2 If A, then B. 3 If B, then C. 4 If C, then not-A. 5 Therefore, both A and not-A 6 But 5 is a contradiction, so the original assumption must be false and not-A must be true. Philosophical example of a Reductio ad Absurdum Socrates’ philosophical opponents, the Sophists, believed that all truth was subjective and relative. Protagoras, one the most famous Sophists, argued that one opinion is just as true as another opinion. The following is a summary of the argument that Socrates used to refute this position as Plato tell us (Theaetetus, 171a,b): 1 One opinion is just as true as another opinion. Socrates assumes the truth of Protagoras’s position.) 2 Protagoras’s critics have the following opinion: Protagoras’s opinion is false and that of his critics is true. 3 Since Protagoras believe premise 1, he believes that the opinion of his critics in premise 2 is true. 4 Hence, Protagoras also believes it is true that: Protagoras’s opinion is false and that of his critics is true. 3
  • 4. 5 Since individual opinion determines what is true and everyone (both Protagoras and his critics) believe the statement “Protagoras’s opinion is false”, it follows that 6 Protagoras’s opinion is false. 4
  • 5. LECTURE 2: The basic concepts of logic Logic is the study of the methods and principles used to distinguish correct reasoning from incorrect reasoning and is a tool for figuring out everything that can truthfully be said, based on what is already known to be true. For this reason, it is related to epistemology, i.e., the theory of knowledge, but its range of application cover the evaluations of arguments in every field of knowledge including metaphysics and ethics. There are objective criteria with which correct reasoning may be defined. If these criteria are not known, they cannot be used. The aim of logic is to discover and make available those criteria that that can be used to test arguments, and to sort good arguments from bad ones. The logician is concerned with reasoning on every subject: science and medicine, metaphysics, ethics and law, politics and commerce, sports and games, and even the simple affairs of everyday life. Very different kinds of reasoning may be used, and all are of interest to the logician, but his concern throughout will be not with the subject matter of those arguments, but with their form and quality. His aim is how to test arguments and evaluate them. It is not the thought processes called reasoning that are the logician’s concern, but the outcomes of these processes, the arguments that are the products of reasoning, and that can be formulated in writing, examined, and analyzed. Each argument confronted raises this question for the logician: Does the conclusion reached follow from the premises used or assumed? Do the premises provide good reasons for accepting the conclusion drawn? The origins of logic In Western intellectual history there have been three great periods of development in logic, with somewhat barren periods sandwiched between them. The first great period was ancient Greece between about 400 BC and 200 CE. The most influential figure here is Aristotle (384-322) who developed a systematic theory of inferences called “syllogisms”. It should also be mentioned that at around the same time as all this was happening in Greece, theories of logic were being developed in India, principally by Buddhist logicians. The second growth period in Western logic was the in the medieval European universities, such as Paris and Oxford, from the 12th to the 14th centuries. After this period, logic largely stagnated till the second half of the 19th century. The development of abstract algebra in the 19th century triggered the start of third and possibly the greatest of the three periods. The logical theories developed in the third period are normally referred as modern logic, as opposed to the traditional logic that preceded it. Developments in logic continued apace throughout the 20th century and show no sign of slowing down yet. “Arguments” in logic As we have seen, it is with arguments that logic is chiefly concerned. An argument is a cluster of propositions in which one is the conclusion and the other(s) are premises offered in its support. This means that in understanding and constructing arguments, it is particularly important to distinguish the conclusion from the premises. Indicator words can help us to do this: words like therefore, thus, so, consequently tell us which claims are to be justified by evidence and reasons, and since, because, for, as, as indicated by, in view of the fact that which other claims are put forward as premises to support them. However, indicator words are not infallible signs of argument because some arguments do not contain indicator words, and some indicator words may appear outside the context of arguments. Arguments may be analyzed and illustrated either by paraphrasing, in which the propositions are reformulated and arranged in logical order; or by diagramming, in which the propositions are numbered and the numbers are laid out on a page and connected in ways that exhibit the logical 5
  • 6. relations among the propositions. To diagram we number each proposition in the order in which it appears, circling the numbers. This avoids the need to restate the premises. Nonarguments Arguing and arguments are important as rational ways of approaching disputes and as careful critical methods of trying to arrive at the truth. Speeches and texts that do not contain arguments can be regarded as nonarguments. There are many different types of nonarguments – including description, exclamation, question, joke, and explanation. Explanation are sometimes easily confused with arguments because they have a somewhat similar structure and some of the major indicator words for arguments are also used in explanations. Explanations should be distinguished from arguments, however, because they do not attempt to justify a claim, or prove it to be true. Recognizing arguments: deduction and induction The difference between inductive and deductive arguments is deep, Because an inductive argument can yield no more than some degree of probability for its conclusion it is always possible that additional information will strengthen or weaken it. Newly discovered facts may cause us to change our estimate of probabilities, and thus may lead us to judge the argument to be better or worse than we thought it was. In the world of inductive argument – even when the conclusion is thought to be very highly probable – all the evidence is never in. It is this possibility of new data, perhaps conflicting with what was believed earlier, that keeps us from asserting that any inductive conclusion is absolutely certain. Deductive arguments, on the other hand, cannot gradually become better or worse. They either succeed or do not succeed in exhibiting a compelling relation between premises and conclusion. The fundamental difference between deduction and induction is revealed by this contrast. If a deductive argument is valid, no additional premises could possibly add to the strength of that argument. For example, if all humans are mortal, and is Socrates is human, we may conclude without reservation that Socrates is mortal – and that conclusion will follow from that premises no matter what else may be true in the world, and no matter what other information may be discovered or added. 6
  • 7. LECTURE 3: The 3 Laws of Thought Some early thinkers, after having defined logic as the science of the laws of thought, went on to assert that there are exactly three basic laws of thought, laws so fundamental that obedience to them is both the necessary and the sufficient condition of correct thinking. These three laws have traditionally been called: 1 The principle of identity. This principle asserts that if any statement is true, then it is true. Using our notation we may rephrase it by saying that the principle of identity asserts that every statement of the form p ⊃ p must be true, that every such statement is a tautology (a tautology is a statement which uses different words to same the same thing). From this follows that 1 Prem. a=a [This is an axiom – a basic assertion that is not proved but can be used to prove other things. The rule of self-identity says that that we may assert a self-identity as a derived step anywhere in a proof, no matter what the earlier lines are.] and that 2 a=b :: b=a and that 3 Fa a = b Fb [This is the equals may substitute for equals rule which is based on the idea that identicals are interchangeable. If a=b, then whatever is true of a is also true of b, and vice versa. This rule holds regardless of what constants replace a and b and what well formed formulas replace Fa and Fb provided that the two well formed formulas are alike except that the constants are interchanged in one or more occurrences.] 2 The principle of non contradiction. This principle assets that no statement can be both true and false. Using our notation we may rephrase it by saying that the principle of non contradiction asserts that every statement of the form p ∙ ∼p must be false, that every such statement is self contradictory. 3 The principle of excluded middle. This principle asserts that every statement is either true or false. Using our notation we may rephrase it by saying that the principle of excluded middle asserts that every statement of the form p ∨ ∼p must be true, that every such statement is a tautology. It is obvious that these 3 principles are indeed true, logically true – but the claim that they deserve a privileged status as the most fundamental laws of thought is doubtful. The first (identity) and the third (excluded middle) are tautologies, but there are many other tautologous forms whose truth is equally certain. And the second (non contradiction) is by no means the only self-contradictory form of statement. We do use these principles in completing truth tables. In the initial columns of each row of a table we place either a T or an F, being guided by the principle of excluded middle. Nowhere do we put both T and F together, being guided by the principle of non-contradiction. And once having put a T under a symbol in a given row, then (being guided by the principle of identity) when we encounter that symbol in other columns of that row we regard it as still being assigned a T. So we could regard the three laws of thought as principles governing the construction of truth tables. 7
  • 8. Nevertheless, some thinkers, believing themselves to have devised a new and different logic, have claimed that these 3 principles are in fact not true, and that obedience to them has been needlessly confining. The principle of identity has been attacked on the ground that things change, and are always changing. Thus for example, statements that were true of the United States when it consisted of the 13 original states are no longer true of the United States today with 50 states. But this does not undermine the principle of identity. The sentence “There are only thirteen states in the United States” is incomplete, an elliptical formulation of the statement that “There were only 13 states in the United States in 1790” and that statement is as true today as it was in 1790. When we confine our attention to complete, non-elliptical formulation of propositions, we see that their truth (or falsity) does not change over time. The principle of identity is true, and does not interfere with our recognition of continuing change. The principle of non-contradiction has been attacked by Hegelian and Marxists on the ground that genuine contradiction is everywhere pervasive, that the world is replete with the inevitable conflict of contradictory forces. That there are conflicting forces in the real world is true, of course - but to call these conflicting forces contradictory is a loose and misleading use of that term. Labour unions and the private owners of industrial plants may indeed find themselves in conflict – but neither the owner nor the union is the negation or the denial or the contradictory of the other. The principle of contradiction, understood in the straightforward sense in which it is intended by logicians, is unobjectionable and perfectly true. The principle of excluded middle has been the object of much criticism, on the grounds that it leads to a two-valued orientation which implies that things in the world must be either white or black, and which therefore hinders the realization of compromise and less than absolute gradations. This objection also arises from misunderstanding. Of course the statement “This is black” cannot be jointly true with the statement “This is white” – where “this” refers to exactly the same thing. But although these two statements cannot both be true, they can both be false. “This” may be neither black nor white; the two statements are contraries, not contradictories. The contradictory of the statement “This is white” is the statement “It is not the case that this is white” and (if “white” is used in precisely the same sense in both of these statements) one of them must be true and the other false. The principle of excluded middle is inescapable. 8
  • 9. Deductive arguments: Validity and truth A successful deductive argument is valid. This means that the conclusion follows with logical necessity from the premises. Remember that truth and falsity are attributes of individual propositions or statements; validity and invalidity are attributes of arguments. Just as the concept of validity does not apply to single propositions, the concept of truth does not apply to arguments. There are many possible combinations of true and false premises a conclusions in both valid and invalid arguments. Consider the following illustrative deductive arguments, each of which is prefaced by the statement of the combination it represents. I Some valid arguments contain only true propositions – true premises and a true conclusion: All mammals have lungs. All whales are mammals. Therefore all whales have lungs. II Some valid arguments contain only false propositions: All four-legged creatures have wings. All spiders have four legs. Therefore all spiders have wings. This argument is valid because, if its premises were true, its conclusion would have to be true also – even though we know that in fact both the premises and the conclusion of this argument are false. III Some invalid arguments contain only true propositions – all their premises are true, and their conclusion are true as well: If I owned all the gold in Fort Knox, then I would be wealthy. I do not own all the gold in Fort Knox. Therefore I am not wealthy. IV Some invalid arguments contain only true premises and have a false conclusion. This can be illustrated with an argument exactly like the previous one (III) in form, changed only enough to make the conclusion false: If Bill Gates owned all the gold in Fort Knox, then Bill Gates would be wealthy. Bill Gates does not own all the gold in Fort Knox. Therefore Bill Gates is not wealthy. The premises of this argument are true, but its conclusion is false. Such an argument cannot be valid because it is impossible for the premises of a valid argument to be true and its conclusion to be false. V Some valid arguments have false premises and a true conclusion: All fishes are mammals. 9
  • 10. All whales are fishes. Therefore all whales are mammals. The conclusion of this argument is true, as we know; moreover it may be validly inferred from the two premises, both of which are wildly false. VI Some invalid arguments also have false premises and a true conclusion: All mammals have wings. All whales have wings. Therefore all whales are mammals. From examples V and VI taken together, it is clear that we cannot tell from the fact that an argument has false premises and a true conclusion whether it is valid or invalid. VII Some invalid arguments, of course, contain all false propositions – false premises and a false conclusion: All mammals have wings. All whales have wings. Therefore all mammals are whales. Deductive arguments: Soundness When an argument is valid, and all of its premises are true, we call it sound. All whales are mammals. All mammals are animals. Hence, all whales are animals. If the president does live in the White House, then he lives in Washington, D.C. The president does live in the White House. So, the president lives in Washington, D.C. The conclusion of a sound argument obviously must be true – and only a sound argument can establish the truth of its conclusion. If a deductive argument is not sound – that is, if the argument is not valid, or if not all of its premises are true – it fails to establish the truth of its conclusion even if in fact the conclusion is true. To test the truth or falsehood of premises is the task of science in general, since premises may deal with any subject matter at all. The logician is not interested in the truth or falsehood of propositions so much as in the logical relations between them. By “logical” relations between propositions we mean those relations that determine the correctness or incorrectness of the arguments in which they occur. The task of determining the correctness or incorrectness of arguments falls squarely within the province of logic. The logician is interested in the correctness even of arguments whose premises may be false. Why not confine ourselves to arguments with true premises, ignoring all others? Because the correctness of arguments whose premises are not known to be true may be of great importance. In science, for example, we verify theories by deducing testable consequences – but we cannot beforehand which theories are true. In everyday life as well, we must often choose between 10
  • 11. alternative courses of action, deducing the consequences of each. To avoid deceiving ourselves we must reason correctly about the consequences of the alternatives, taking each as a premise. If we were interested only in arguments with true premises, we would not know which set of consequences to trace out until we knew which of the alternative premises was true. But if we knew which of the alternative premises was true, we would not need to reason about it at all, since our purpose in reasoning was to help us decide which alternative premise to make true. To confine our attention to arguments with premises known to be true would therefore be self-defeating. Deductive arguments: Proving invalidity 1 See whether the premises are actually true and the conclusion is actually false. If they are, then the argument is invalid. If they are not, or if you can’t determine whether the premises and the conclusion are actually true or false, then go on to step 2. 2 See if you can conceive a possible scenario in which the premises would be true and the conclusion false. If you can, then the argument is invalid. If you can’t, and it is not obvious to you that the argument is valid, then go on to step 3. 3 Try to construct a counterexample to the argument – that is, a second argument that has exactly the same form as the first argument, but whose premises are obviously true and whose conclusion is obviously false. If you can construct such a counterexample, then the argument is invalid. If you can’t, then it is usually safe to assume that the argument is valid. Counterexample method of proving invalidity First, determine the logical pattern, then the form of the argument that you are testing for invalidity, using letters (A,B,C,D) to represent the various terms of the argument. Then, construct a second argument that has exactly the same form as the argument you are testing but that has premises that are obviously true and a conclusion that is obviously false. Example: Some Republicans are conservative, and some Republicans are in favour of capital punishment. Therefore, some conservatives are in favour of capital punishment. Logical pattern 1 Some Republicans are conservatives. 2 Some Republicans are in favour of capital punishment. 3 Therefore, some conservatives are in favour of capital punishment. (Note that in logic some means at least one it does not mean some but not all.) Form 1 Some A’s are B. 2 Some A’s are C. 3 Therefore, some B’s are C’s. Construct a second argument that has exactly the same form and that has obviously true premises and an obviously false conclusion. 1 Some A’s are B. 1 Some fruits are apples (true) 11
  • 12. 2 Some A’s are C. 2 Some fruits are pears (true) 3 Therefore, some B’s are C’s. 3 Some apples are pear (false) 12
  • 13. LECTURE 4: Propositional logic Although categorical logic is the oldest developed in the Western philosophical tradition, it is not now believed to be the most basic part of logic. This role is reserved for propositional logic. Propositional logic studies arguments whose validity depends on “if then”, “and,” “or,” “not”, and similar notions. We will cover the very basics of it. The earliest development of propositional logic (known also as truth-functional logic or sentential logic) took place among the Stoics, who flourished from about the third century B.C.E. until the second century C.E. But it was in the late nineteenth and twentieth centuries that the real power of truth-functional logic became apparent. Modern symbolic logic is not encumbered (as Aristotelian logic was) by the need to transform deductive arguments into syllogistic form. That task can be laborious. Freed from the need to make such transformations, we can pursue the aims of deductive analysis more directly. In modern logic it is not syllogisms (as in the Aristotelian tradition) that are central, but logical connectives, the relations between elements that every deductive argument, syllogism or not, must employ. The internal structure of propositions and arguments is the focus of modern logic. The “logic of sentences” is one of the bases on which modern symbolic logic rests, and as such it is important in such intellectual areas as set theory and the foundations of mathematics. It is also the model for electrical circuits of the sort that are the basis of digital computing. But truth-functional logic is also a useful tool in the analysis of arguments. Therefore, the study of truth-functional logic can be beneficial in several ways. For one thing, it allows us to learn something about the structure of language that we would not learn any other way. For another, we get a sense of what it is like to work with a very precise, non-mathematical system of symbols that is nevertheless very accessible to nearly any student willing to invest a modest amount of effort. The model of precision and clarity that such systems provide can serve us well when we communicate with others in ordinary language. However, in order to understand the internal structure of propositions and argument we must master the special symbols that are used in modern logical analysis. It is with them that we can more fully achieve the central aim of deductive logic: to discriminate valid arguments from invalid arguments. In sum, the symbolic notation of modern logic is an exceedingly powerful tool for the analysis of arguments. Symbols and translation 1 In propositional logic, the world conjunction refers to a compound statement. A compound statement, such as “This lesson was stimulating, and I learned a lot, is symbolized by two variables joined by a dot (for example p ∙ q ). [If in any case we are unsure whether a statement is simple or compound, we must ask, “What does the statement mean?” Does the statement consists of two simple statements? If it does, then it is compound. If it doesn’t, then it is simple.] For the purposes of propositional logic, the following words are all equivalent and can be symbolized by the dot: and, but, yet, while, whereas, although, though, however. 13
  • 14. 2 Negation is the use of the word “not” (or an equivalent word or phrase) to deny a statement. The conventional symbol for negation is the tilde, ∼. 3 A disjunction is an “or” statement – that is, a statement that consists of two (or more) statements set apart, usually by the word “or”. The symbol for disjunction is the lower case v, also called the wedge. The word “or” has two possible senses. The exclusive sense eliminates one of the possibilities. For example, a flight attendant may tell you, “For dinner you may have chicken or fish.” The nonexclusive sense does not exclude either possibility. For example, a doctor may advise you that “when you are feeling dehydrated, you should drink water or natural fruit juice.” It is true when either of the two statement is true, and it is also true when both statements are true. For the purposes of propositional logic, it is conventional to take the word “or” in its nonexclusive sense. 4 A conditional statement is an if-then statement consisting of two parts. The first part of the statement, which follows “if” and precedes “then,” is called the antecedent. The symbol for the implication involved in an if then statement is the horseshoe, ⊃. The only time a conditional is false is when the antecedent is true and the conclusion is false. It may be helpful to think of the truth table for conditional statements in terms of the guiding legal principle that a person is presumed innocent until proven guilty. In a similar way, a conditional is presumed true until proven false. The only thing that can definitively show that a conditional is false is a true antecedent followed by a false consequent. 5 Any two true statements materially imply one another and any two false statements also materially imply one another, since they are either both true, or both false. The symbol for material equivalence is the triple bar sign ≡. We can read the triple bar sign to say “if and only if”. Two statements are logically equivalent when the statement of their material equivalence is a tautology. A tautology is a statement that it is true in every possible case. Statements that are logically equivalent may be substituted for one another, while statements that are merely materially equivalent cannot replace one another. We now have a propositional language, with precise rules for constructing arguments and testing validity. Our language can help to test arguments. ∼ P = Not P (P ∙ Q) = Both P and Q (P v Q) = Either P or Q (P ⊃ Q) = If P then Q (P ≡ Q) = P if and only if Q A grammatically correct formula of this language is called a wff, or well formed formula (pronounce woof – as in wood). The truth value of any truth functional connective depends upon (is a function of) the truth or falsity of the statements it connects. Truth values for a variable (which stands for a statement) are indicated as true, T, or false, F. Truth tables A truth table is a listing of all possible truth values for the variables in an argument form. 14
  • 15. In a valid argument it is impossible for all of the premises to be true and the conclusion false. So in examining the truth table, we look for instances in which all the premises are true. If there is any instance of all true premises followed by a false conclusion, an F under the conclusion column, the argument is invalid. It does not matter if there are other instances in the truth table where all the premises are true and the conclusion is true, too. Any two arguments that share the same argument form are either both valid or both invalid. When we know that an argument form is valid, we know that any argument that fits that form is valid. The truth tables for the five basic truth functional symbols Negation: "not" or "it is not the case that" P ∼P T F F T Conjunction : and, but, while. P Q (P ∙ Q) T T T T F F F T F F F F Disjunction: or, unless P Q (P v Q) T T T T F T F T T F F F Conditional: if….then P Q (P ⊃ Q) T T T T F F F T T F F T Material equivalence: if and only if P Q (P ≡ Q) T T T T F F F T F F F T 15
  • 16. Formal proof When we use the method of deduction, we actually deduce (or derive) the conclusion from the premises by means of a series of basic truth-functionally valid argument patterns. This is a lot like thinking through the argument, taking one step at a time to see how, once we have assumed the truth of the premises, we eventually arrive at the conclusion. The first few basic argument patterns are referred to as truth-functional rules because they govern what steps we are allowed to take in getting from the premise to the conclusion. We define a formal proof that a given argument is valid as a sequence of statements each of which is either a premise of that argument or follows from preceding statements of the sequence by an elementary valid argument, such that the last statement in the sequence is the conclusion of the argument whose validity is being proved. We define an elementary valid argument as any argument that is a substitution instance of an elementary valid argument form. One matter to be emphasized is that any substitution instance of an elementary valid argument form is an elementary valid argument. Thus the argument (A ∙ B) ⊃ [C ≡ (D ∨ E)] (A ∙ B) ∴ C ≡ (D ∨ E) is an elementary valid argument because it is a substitution instance of the elementary valid form modus ponens (M.P.). It results from p ⊃ q p ∴ q by substituting A ∙ B for p and C ≡ (D ∨ E) for q, and is therefore of that form even though modus ponens is not the specific form of the given argument. 1 Modus ponens, also known as affirming the antecedent, is the most elementary among the rules of inference, but the same process can be applied to all the others. It can be applied also to: 2 Modus tollens, also known as denying the consequent. If you have a conditional claim as one premise and if one of your other premises is the negation of the consequent of that conditional, you can write down the negation of the conditional’s antecedent as a new line in your deduction. 3 The pure hypothetical syllogism also known as chain argument rule allows you to derive a conditional from two you already have, provided the antecedent of one of your conditionals is the same as the consequent of the other. 4 Disjunctive argument, from a disjunction and the negation of one disjunct, the other disjunct may be derived. 16
  • 17. 5 Constructive dilemma, the disjunction of the antecedents of any two conditionals allows the derivation of the disjunction of their consequents. (p ⊃ q) ∙ (r ⊃ s) p v r ∴ q v s 5b Destructive dilemma, the disjunction of the negations of the consequents of two conditionals allows the derivation of the disjunction of the negations of their antecedents. (p ⊃ q) ∙ (r ⊃ s) ∼q v ∼s ∴ ∼p v ∼r God and Evil An age old argument that God is either not all powerful or not all good goes like this: If God is all powerful, then he would be able to abolish evil. If God is all good, then he would not allow evil to be. Either God is not able to abolish evil, or God allows evil to be. Therefore, either God is not all powerful, or God is not all good. (p ⊃ a) ∙ (g ⊃ ∼e) ∼a v e ∴ ∼p v ∼g This argument is an instance of the destructive dilemma. 6 Simplification, if the conjunction is true, then of course the conjunct must all be true. You can pull out one conjunct from any conjunction and make it the new line in your deduction. 7 Conjunction, this rules allows you to put any two lines of a deduction together in the form of a conjunction. p q ∴ p ∙ q 8 Addition, clearly no matter what claims p and q might be, if p is true then either p or q must be true. The truth one disjunt is all it takes to make the whole disjunction true. p ∴ p v q 17
  • 18. Inconsistency Consistency and inconsistency are important because, among other things, they can be used to evaluate the overall rationality of a person’s stated position on something. If truth values can be assigned to make all the premises of an argument true and its conclusion false, than that shows the argument to be invalid. If a deductive argument is not invalid it must be valid. So, if no truth-value assignment can be given to the component simple statements of an argument that makes its premises true and its conclusion false, then the argument must be valid. Although this follows from the definition of validity, it has a curious consequence. The essence of the matter is simply shown in the case of the following argument, whose openly inconsistent premises allow us validly to infer an irrelevant and fantastic conclusion: Today is Sunday Today is not Sunday Therefore, the moon is made of green cheese. In symbols, we have 1 S 2 ∼S 3 ∴ M The formal proof of its validity is almost immediately obvious: 3 S v M 1, Add. 4 M 3,2, D.S. What is wrong here? How can such a meagre and even inconsistent premises make any argument in which they occur valid? Note first that if an argument is valid because of an inconsistency in its premises, it cannot be possibly a sound argument. If premises are inconsistent with each other, they cannot possibly all be true. No conclusion can be established to be true by an argument with inconsistent premises, because its premises cannot possibly all be true themselves. The present situation is closely related to the so-called paradox of material implication. As far as the latter goes, the statement form ∼p ⊃ (p ⊃ q) is a tautology, having all its substitutions instances true. Its formulation in English asserts that If a statement is false then it materially implies any statement whatever, which is easily proved by means of truth tables. What has been established in the present discussion is that the argument form p ∼p ∴ q is valid. We have proved that any argument with inconsistent premises is valid, regardless of what its conclusion may be. Its validity may be established either by a truth table or by the kind of formal proof given above. The premises of a valid argument imply its conclusion not merely in the sense of material implication, but logically or strictly. In a valid argument, it is logically impossible for the premises to be true when the conclusion is false. And this situation obtains whenever it is logically 18
  • 19. impossible for the premises to be true, even when the question of the truth or falsehood of the conclusion is ignored. Its analogy with the corresponding property of material implication has led some writers on logic to call this a paradox of strict implication. In view of the logician technical definition of validity, it does not seem to be especially paradoxical. The alleged paradox arises primarily from treating a technical term as if it were a term of ordinary, everyday language. The foregoing discussion helps to explain why consistency is so highly prized. One reason, of course, is that inconsistent statements cannot both be true. This fact underlies the strategy of cross- examination, in which an attorney may seek to manoeuvre a hostile witness into contradicting himself. If testimony affirms incompatible or inconsistent assertions, it cannot all be true, and the witness’s credibility is destroyed or at least shaken. A witness giving contradictory testimony testifies to some proposition that is false. When it has been once established that a witness has lied under oath (or is perhaps thoroughly confused) no sworn testimony of that witness can be fully trusted. Lawyers quote the Latin saying: Falsus in unum, falsus in omnibus; untrustworthy in one thing, untrustworthy in all. But another reason why inconsistency is so repugnant is that any and every conclusion follows logically from inconsistent statements taken as premises. Inconsistent statements are not meaningless; their trouble is just the opposite. They mean too much. They mean everything, in the sense of implying everything. And if everything is asserted, half of what is asserted is surely false, because every statement has a denial. The preceding discussion incidentally provides us with an answer to the old riddle: What happens when an irresistible force meets an immovable object? The description involves a contradiction. For an irresistible force to meet an immovable object, both must exist. There must be an irresistible force and there must also be an immovable object. But if there is an irresistible force there can be no immovable object. Here is the contradiction made explicit: There is an immovable object, and there is no immovable object. Given these inconsistent premises, any conclusion may validly be inferred. So the correct answer to the question “What happens when an irresistible force an immovable object?” is Everything! Although devastating when uncovered within an argument, inconsistency can be highly amusing, as in the very common saying: That restaurant is so crowded, that nobody goes there any more. And speaking of the partner in a long and happy marriage: We have a great time together, even when we are not together. Such utterances are funny because the contradictions they harbour (and therefore the nonsense of the remarks when taken literally) appear not to be recognized by their authors. So we chuckle when we read of the schoolboy who said that the climate of the Australian interior is so bad that the inhabitants don’t live there any more. Such inadvertent and unrecognized inconsistencies are sometimes called Irish Bulls. Sets of propositions that are internally inconsistent cannot all be true, as matter of logic. But human beings are not always logical and do utter, and sometimes may even believe, two propositions that contradict one another. This may seem difficult to do, but we are told Lewis Caroll, a very reliable authority in such matters, that the White Queen in Alice in Wonderland made a regular practice of believing six impossible things before breakfast! 19
  • 20. LECTURE 5: Inductive arguments: Strength and cogency However, there is a major drawback to all deductive arguments. You cannot get any more out of the conclusion than is present in the premises. But when we want to enlarge our knowledge of the world – especially when we engage in empirical investigation, as natural scientists do – deductive arguments are not sufficient, because we want to go beyond the premises we begin with. In the vast majority of arguments one finds in the natural sciences and in such social sciences as psychology, geography, history, linguistics, and anthropology, the reasons lend weight to the conclusion without demonstrating conclusively the truth of those conclusions. These arguments are called inductive arguments. If the argument is such that true premises would make the conclusion highly probable, then we say that the argument is a strong argument. For example, in a murder trial the mere fact that the suspect own a gun of the same calibre as that which killed the victim adds very little weight to the conclusion that the suspect is the murderer. The prosecutor’s case would be greatly strengthened if it could be shown that the bullet which killed the victim was fired from the suspect’s own gun. This, too, would hardly be convincing without additional evidence, as for example, that the suspect had a motive for killing the deceased, had threatened the victim, was seen by eyewitnesses in the vicinity of the murder immediately before and after the fatal shots were fired, and so forth. In spite of the accumulation of evidence, the argument against the suspect still is not conclusive, since it is possible for all this to be true even though the victim was shot by someone else who was trying to frame the suspect. A strong argument that actually have true premises is a cogent argument. A cogent argument does not absolutely guarantee the conclusion (as does a sound argument), but it does give us good reasons for believing the conclusion. The author does not claim that the conclusion necessarily follows from the premises but claims merely that the premises make the conclusion highly probable. For instance, if we say that every horse that has ever been observed has had a heart, we reach the cogent conclusion that every horse has a heart. Induction and Mill’s method In the preceding lectures we have dealt with deductive arguments, which are valid if their premises establish their conclusions demonstratively, but invalid otherwise. There are very many good and important arguments, however, whose conclusions cannot be proved with certainty. Many causal connections in which we rightly place confidence can be established only with probability – though the degree of probability may be very high. Thus we can say without reservation that smoking is a cause of cancer, but we cannot ascribe to that knowledge the kind of certainty that we ascribe to our knowledge that the conclusion of a valid deductive argument is entailed by its premises. Deductive certainty is, indeed, too high a standard to impose when evaluating our knowledge of facts about the world. Of all inductive arguments there is one type that is most commonly used: argument by analogy. An analogy is a likeness or comparison; we draw an analogy when we indicate one or more respects in which two or more entities are similar. An argument by analogy is an argument in which the similarity of two or more entities in one or more respects is used as the premis(es); its conclusion is that those entities are similar in some further respect. Not all analogies are used for the purposes of argument; they also may serve some literary effect, or for purposes of explanation. Because analogical arguments are inductive, not deductive, the terms validity and 20
  • 21. invalidity do not apply to them. The conclusion of an analogical argument, like the conclusion of every inductive argument, has some degree of probability, but it is not claimed to be certain. There are some 6 criteria used in determining whether the premises of an analogical argument render its conclusion more or less probable. These are: 1 The number of entities between which the analogy is said to hold. 2 The variety, or degree of dissimilarity, among those entities or instances mentioned only in the premises. 3 The number of respects in which the entities involved are said to be analogous. 4 The relevance of the respects mentioned in the premises to the further respect mentioned in the conclusion. 5 The number and importance of non-analogies between the instances mentioned only in the premises and the instance mentioned in the conclusion. 6 The modesty (or boldness) of the conclusion relative to the premises. Refutation by logical analogy is an effective method of refuting both inductive and deductive arguments. To show that a given argument is mistaken, one may present another obviously mistaken argument that is very similar in form to the argument under attack. Causal connections To exercise any measure of control over our environment, we must have some knowledge of causal connections. To cure some disease, for example, physicians must know its cause, and they should understand the effects (including the side effects) of the drugs they administer. The relation of cause and effect is of the deepest importance – understanding it, however, is complicated by the fact that there are several different meanings of the word cause. By cause we sometimes mean a necessary condition; sometimes a sufficient condition; sometimes a condition that is both necessary and sufficient; and sometimes something that is a contributory factor. Compare, for instance, the following claims: 1 C is a necessary condition, or necessary cause, for E. Without C, E will not happen; E ⊃ C. 2 C is a sufficient condition, or sufficient cause, for E. Given C, E is bound to happen; C ⊃ E. 3 C is a necessary and sufficient condition, or sufficient cause, for E. Without C, E will not happen and given C, E is bound to happen. Bi-conditional: (E ⊃ C) ∙ (C ⊃ E). 4 C is a contributory cause of E. (C is one of several factors that, together, produce E.) These claims are different from each other in important ways. Claims (a), (b), and (c) make the clearest assertion from a logical point of view. Often, however, it is causal factors (d) that we are trying to discover. Both in ordinary speech and in scientific research, we often speak of a contributory factor, as in (d) as the cause. If we were using language strictly, such a claim would be an oversimplification. Consider, for instance, the much discussed claim that high cholesterol in the blood causes heart disease. High cholesterol may be one contributory factor to the development of heart disease but there are many other contributory factors, including genetic inheritance, fitness level, and diet. When we read reports in the media and elsewhere of the results of scientific studies, it is important to check to see whether a causal claim is made. Causal claims are not always stated using the words 21
  • 22. cause and effect. Many other words and expressions are used in stating causal claims, Here are some of them: A produced B A was responsible for B A brought about B A led to B A was the factor behind B A created B A affected B A influenced B B was the result of (or resulted from) A As a result of A, B occurred B was determined by A A was a determinant of B B was induced by A B was the effect of A B was an effect of A When we evaluate inductive arguments, it is crucially important to see whether a causal claim is made. Causal claims require a different justification from inductive generalizations; in addition they have different implications for action. Mill’s Methods The nineteenth-century philosopher John Stuart Mill proposed methods for discovering causal relationships. Of Mill’s methods, I will briefly describe three: the Method of Agreement, the Method of Difference, and the Joint Method of Agreement and Difference. As we shall see, Mill’s methods have some limitations. However, they are still useful in some circumstances. The method of Agreement To see how this works, suppose that a group of ten friends visit a restaurant and have a nice diner. Afterward five of them develop acute stomach pains. They were all in the restaurant together; investigating to find the cause, they begin by operating from the assumption that the stomach pain resulted from what they ate in the restaurant. They ate in the same restaurant, but they did not all eat the same thing. To use Mill’s method of agreement to explore this topic, they would list what each person ate and then check to see whether there was one food eaten by all the people who suffered from stomach pains. If there were, they would tentatively infer a causal hypothesis: that item was the cause of the stomach pains. In this case, the cause would be a sufficient condition (given the background circumstances) of having the stomach pains. Suppose that Paul, John, Mary, Sue, and David were the ones who became ill, that they ate different main dishes and different desserts, but they all had Caesar salad with a sharp cheese dressing. Given this evidence, there is reason to suspect that the salad or the sharp cheese dressing caused their illness. It is worth noting that the exploration need not stop at this point. The method of agreement can be used to explore the matter further. For example, did other patrons who consumed this dressing suffer stomach pains? If the group were to discover that thirty-five others ate the sharp cheese dressing, and of these only ten experienced ill effects, that would be evidence against their causal hypothesis that the dressing caused the stomach pains. (Perhaps sharp cheese dressing, in conjunction with some other factor or factors, caused the discomfort. Such hypotheses could also be 22
  • 23. explored using Mill’s methods.) The investigating patrons could use the method of agreement again with the broader group of fifteen people to try to discover the cause by finding out what, if anything, all these people had in common relative to their illness. The method of difference As we might expect from its name, in the method of difference we are looking for the factor that makes the difference. Suppose that 100 people are exposed to Disease D and of them, only three catch it. Following the method of difference, we would seek what feature differentiates these three people from the others. If we could find a property that they shared, and that none of the other people possessed, we would have ground for the causal hypothesis that the shared characteristic made the difference in catching Disease D. If, for instance, these three people, and only they, had scarlet fever as children, we would tentatively form the hypothesis that having had scarlet fever made them more vulnerable, and that this was a cause (in the sense of necessary condition) of getting Disease D. The joint method of agreement and difference This method consists of using the method of agreement and the method of difference together. If an aspect, x, is common in all examined cases in which y does not occur, then we have some reason to suspect that x is the cause of y. The application of the Joint method supports the conclusion that x is a necessary and sufficient condition of y. That is to say, (y ⊃ x) ∙ (x ⊃ y). Mill’s methods presuppose that there is a cause to be found, and that we have enough knowledge to know what sorts of factors to look for. Using these methods, we arrive at causal hypotheses. There are some pitfalls in the method. An obvious one is that we may have made a faulty assumption when we identified the factors to examine, (Our list of possible factors may have been too short.) In the case of the sharp cheese dressing, for example, it is not hard to imagine various ways in which the causal inference might have gone wrong. The overall assumption that the cause must have been something in the food might be mistaken. Paul, John, Mary, Sue, and David might have all been exposed on a previous day to a certain flu bug, and the stomach pain might have been part of that flu. By concentrating their attention on what was eaten at the restaurant, the friends would miss this factor and reach a faulty causal conclusion. This is not to say that Mill’s methods are useless – only that they have to be applied with care. We must remember that our results are only as good as the assumptions used in formulating the problem, and second, that the conclusion is a causal hypothesis. The inductive method The inductive approach to knowledge is based on the impartial gathering of evidence or the setting up of appropriate experiments, such that the resulting information can be examined and conclusions drawn from it. It assumes that the person examining it will come with an open mind and that theories framed as a result of that examination will then be checked against new evidence. In practice, the method works like this: 1 Evidence is gathered, and irrelevant factors are eliminated as far as possible; 2 Conclusions are drawn from that evidence, which lead to the framing of a hypothesis; 3 Experiments are devised to test out the hypothesis, by seeing if it can correctly predict the results of those experiments; 4 If necessary, the hypothesis is modified to take into account the results of those later experiments; 23
  • 24. 5 A general theory is framed from the hypothesis and related experimental data; 6 That theory is then used to make predictions, on the basis of which it can be either confirmed or disproved. It is clear that this process can yield no more than a very high degree of probability. There is always going to be the chance that some new evidence will show that the original hypothesis, upon which a theory is based, was wrong. Most likely, it is shown that the theory only applies within a limited field and that in some unusual sets of circumstances it breaks down. Even if it is never disproved, or shown to be limited in this way, a scientific theory that has been developed using this inductive method is always going to be open to the possibility of being proved wrong. Without that possibility, it is not scientific. Example The final step in this process (i.e., the theory used to make predictions confirming or disproving its validity) is well illustrated by the key prediction that confirmed Einstein’s general theory of general relativity. Einstein argued that light would bend within a strong gravitational field and therefore that stars would appear to shift their relative positions when the light from them passed close to the Sun. This was a remarkably bold prediction to make. It could only be tested by observing the stars very close to the edge of the Sun as it passed across the sky and comparing this with their position relative to other stars once the light coming from them was no longer affected by the Sun’s gravitational pull. But the only time they could be observed so close to the Sun was during an eclipse. Teams of observers went to Africa and South America to observe an eclipse in 1919. The stars did indeed appear to shift their positions to a degree very close to Einstein’s predictions, thus confirming the theory of general relativity. Scientific laws With the development of modern science, the experimental method led to the framing of laws of nature. It is important to recognize exactly what is meant by law in this case. A law of nature (in the scientific sense) does not have to be obeyed. A scientific law cannot dictate how things should be, it simply describes them. The law of gravity does not require that, having tripped up, I should adopt a prone position on the pavement – it simply describes the phenomenon that, having tripped, I fall. Hence, if I trip and float upward, I am not disobeying a law, it simply means that I am in an environment (e.g. in orbit) in which the phenomenon described by the law of gravity does not apply. The law cannot be broken in these circumstances, only be found to be inadequate to describe what is happening. 24
  • 25. LECTURE 6: Logical Fallacies Logical fallacies: Fallacies of relevance A logical fallacy is an argument that contains a mistake in reasoning. Fallacies can be divided in two broad groups: fallacies of relevance and fallacies of insufficient evidence. Fallacies of relevance are argument in which the premises are logically irrelevant to the conclusion. Fallacies of insufficient evidence are arguments in which the premises, though logically relevant to the conclusion, fail to provide sufficient evidence for the conclusion. During this lecture we will discuss fallacies of relevance. We will discuss fallacies of insufficient evidence in the next lecture. The concept of relevance A statement is relevant to another if it provides at least some evidence or reason for thinking that the second statement is true or false. There are three ways in which a statement can be relevant or irrelevant to another. A statement can be positively relevant, negatively relevant, or logically irrelevant to another statement. A statement is positively relevant to another statement if it provides at least some reason for thinking that the second statement is true. A statement is positively relevant to another statement if it counts in favour of that statement. Here are several examples: First argument: Dogs are cats. Cats are feline. So dogs are felines. Second argument: All dogs have five legs. Rick is a dog. So Rick has five legs. Third argument: Most Penn State Univ. students are resident of Pennsylvania. Marc is a Penn State Univ. student. So, Mark is probably a resident of Pennsylvania. Fourth argument: Carole is a woman. Therefore, Carole enjoys knitting. Each of these premises is positively relevant to its conclusion. That is, each provides at least some evidence or reason for thinking that the conclusion is true. In the first and second argument, the premises provide logically conclusive reasons for accepting the conclusion. In the fourth argument, the premise - Carole is a woman - provides neither probable nor conclusive reasons for accepting the conclusion – Carole enjoys knitting. However, the premise does make the conclusion slightly more probable than it would be if the conclusion were considered independently of that premise. Thus, premise does provide some evidence for the conclusion, and hence is positively relevant to it. These examples highlight two important lessons about the concept of relevance. First, a statement can be relevant to another statement even if the first statement is completely false. Thus, in the first example, the statement “Dogs are cats” is clearly false. Nevertheless, it is relevant to the statement “Dogs are felines” because if it were true, then the latter statement would have to be true as well. Second whether a statement is relevant to another usually depends on the context in which the statements are made. Thus, in the second example, the statement “All dogs have five legs” is positively relevant to the statement “Rick has five legs” only because it is conjoined with the statement “Rick is a dog.” 25
  • 26. Statements that count against other statements are said to be negatively relevant to those statements. Here are some examples: Joe is an uncle. Therefore, Joe is a female. Althea is two years old. Thus, Althea probably goes to college. Mark is a staunch Republican. Therefore, Mark probably favours higher taxes. In each of these examples, the premises are negatively relevant to the conclusion. Each premise, if true, makes the conclusion at least somewhat less likely. Statements can be logically irrelevant to other statements. A statement is logically irrelevant to another statement if it counts neither for nor against that statement. Here are some examples: Last night I dreamed that Germany will win the next World Cup. Therefore, Germany will win the next World Cup. The earth revolves around the sun. Therefore, marijuana should be legalized. Julie is ugly. Therefore, Julie should not be allowed to board the train. None of these premises provides even the slightest reason for thinking that their conclusions are either true or false. Thus, they are logically irrelevant to those conclusions. Fallacies of relevance A fallacy of relevance occurs when an arguer offers reasons that are logically irrelevant to his or her conclusion. Like most popular fallacies, fallacies of relevance often seem to be good arguments but are not. There are some 11 common fallacies of relevance: 1 Personal attack (ad hominem): The rejection of a person’s argument or claim by means of an attack on the person’s character rather than the person’s argument or claim. Professor Platter has argued against the theory of evolution. But Platter is a heavy drinker and an egoist who has never given a single penny to charity in all his life. I absolutely refuse to listen to him. 2 Attacking the motive: Criticizing a person’s motivation for offering a particular argument or claim, rather than examining the worth of the argument or claim itself. Mr. Platter has argued that we need to build a new middle school. But Mr. Platter is the owner of Platter’s Construction Company. He will make a fortune if his company is picked to build the new school. Obviously, Platter’s argument is a lot of self-serving baloney. 3 Look who is talking (tu quoque): The rejection of another person’s argument or claim because that person is a hypocrite. 26
  • 27. My opponent has accused me of running a negative political campaign. But my opponent has run a much more negative campaign than I have. Just last week he has accused me of graft, perjury and all sort of other wrong doings. 4 Two wrongs make a right: Attempting to justify a wrongful act by claiming that some other act is just as bad or worse. I admit we plied Olympic officials with booze, free ski vacations, and millions of dollars in outright bribes in order to be selected as the site of the next winter Olympics. But everybody does it. That’s the way the process works. Therefore, paying those bribes was not really wrong. 5 Appeal to force: Threatening to harm a reader or listener, when the threat is irrelevant to the truth of the arguer’s conclusion. I am telling you the truth and if you do not believe I will call my big brother who will teach you a lesson. 6 Appeal to pity: Attempting to evoke feelings of pity or compassion, when such feelings, however understandable, are not relevant to the truth of the arguer’s conclusion. Officer, I know I was going too fast. But I do not deserve a speeding ticket. I have had a really bad day. My mother is sick in hospital and my father had a heart attack at hearing the news. Today, I have also been fired from my job, and I have no money left in the bank to pay the bills. 7 Bandwagon argument: An appeal to a person’s desire to be popular, accepted, or valued rather than to logically relevant reasons or evidence. All the popular, cool kids wear Mohawk haircuts. Therefore, you should, too. 8 Straw man: The misrepresentation of another person’s position in order to make that position easier to attack. Professor Platter has argued that the Bible should not be read literally. Obviously, Platter believes that any reading of the Bible is as good as any other. But this would mean that there is no difference between a true interpretation of Scripture and a false interpretation. Such a view is absurd. 9 Red herring: An attempt to sidetrack an audience by raising an irrelevant issue and then claiming that the original issues has been effectively settled by the irrelevant diversion. Frank has argued that Volvos are safer cars than Ford Mustang convertibles. But they are clunky, boxlike cars, whereas Mustang convertibles are sleek, powerful, and sexy. Clearly, Frank does not know what he is talking about. 10 Equivocation: The use of a key word in an argument in two or (or more) different senses. In the summer 1940, Londoners were bombed almost every night. To be bombed is to be intoxicated. Therefore, in the summer 1940, Londoners were intoxicated almost every night. 27
  • 28. 11 Begging the question: Stating or assuming as a premise the very thing one is seeking to prove as a conclusion. I am entitled to say whatever I choose, because I have a right to say whatever I please. Logical fallacies: Fallacies of insufficient evidence In the last lecture we looked at fallacies of relevance, fallacies that occur when the premises are logically irrelevant to the truth of the conclusion. Fallacies of insufficient evidence are fallacies in which the premises, though relevant to the conclusion, fail to provide sufficient evidence for the conclusion. There are some nine common fallacies of insufficient evidence: 1 Inappropriate appeal to authority: Citing a witness or an authority that is untrustworthy. My hairdresser told me that the extraterrestrials built the lost city of Atlantis. So, it is reasonable to believe that extraterrestrial did build the lost city of Atlantis. 2 Appeal to ignorance: Claiming that something is true because no one has proven it false, or vice versa. Bigfoot must exist. No one has proved that it does not. 3 False alternatives: Posing a false either/or choice. The choice in this election is clear. Either we elect a staunch conservative as our next president, or we watch our country slides into anarchy and economic depression. Clearly, we don’t want our country to slide into anarchy and economic depression. Therefore, we should elect a staunch conservative as our next president. 4 Loaded question: Posing a question that contains an unfair or unwarranted presupposition. Are you still dating that total loser Phil? Yes. Well, at least you admit he is a total loser. 5 Questionable cause: Claiming, without sufficient evidence, that one thing is the cause of something else. Two days after I drank lemon tea, my head cold cleared up completely. Try it. It works. 6 Hasty generalization: Drawing a general conclusion from a sample that is biased or too small. BMWs are a pile of junk. I have two friends who drive BMWs, and both of them have had nothing but trouble from those cars. 7 Slippery slope: Claiming, without sufficient evidence, that a seemingly harmless action, if taken, will lead to a disastrous outcome. 28
  • 29. Immediate steps should be taken to reduce violence in children’s television programming. If this violent programming is allowed to continue, this will almost certainly lead to fights and acts of bulling in school playgrounds. This in turn will lead to an increase in juvenile delinquency and gang violence. Eventually, our entire society will become engulfed in an orgy of lawlessness and brutality. 8 Weak analogy: Comparing things that are not really comparable. Nobody would buy a car without first taking it for a test drive. Why then should you not taste what is inside a box before buying a product? 9 Inconsistency: Asserting inconsistent premises, asserting a premise that is inconsistent with the conclusion, or arguing for inconsistent conclusions. Note found in a Forest Service suggestion box: Park visitors need to know how important it is to keep this wilderness area completely pristine and undisturbed. So why not put a few signs to remind people of this fact? 29
  • 30. LECTURE 10: Philosophy of religion The Concise Oxford Dictionary defines religion as “the belief in a superhuman controlling power, especially in a personal God or gods entitled to obedience and worship.” This is a loose definition that encompasses many beliefs and worship. Our book provides an examination of some philosophical issues concerning religion from a Western perspective. Muslim contend that Islam is not a religion; it is a way of life. Similarly Taoism is considered by many not to be a religion but “The Way.” Buddhism, which does not serve a God, believes in “The Path.” Nevertheless, it would seem that whatever name or designation is given to a particular faith or belief, the needs of the adherents do not differ; in that, there is universal agreement. It can be described as the need and the search for the holy and/or the infinite, God, the meaning of life, etc. The study of religion Most scholars agree that the nineteenth century was the formative period when the study of modern religions got under way. Many disciplines were involved, including the philological sciences, literary criticism, psychology, anthropology, and sociology. Questions immediately come up that go beyond the recorded facts. What, for example, is the religious experience and how is it exhibited? What are the principles at work in the various religions? Are there laws in place in the religions, and how do they affect the adherents? In addition, there were the questions of truth or falsity, and the reliability of the recorded history of each religion. In short, it would be fair to say that the whole subject was fraught with controversy. Classifying religions The whole issue of true and false religions and a classification that demonstrated the claims of each led to the necessity to defend one religion against another. Unfortunately, this type of classification, which is arbitrary and subjective, continues to exist. For example, in the sixteenth century, Martin Luther, the great Protestant Reformer, went so far as to label Muslims, Jews, and Roman Catholic Christians to be false. He held that the gospel of Christianity understood from the viewpoint of justification by grace through faith was the true standard. Another example would be Islam, in which religions are classified into three groups: the wholly true, the partially true, and the wholly false. That classification is based in the Qur’an (Koran, the Islamic sacred scripture) and is an integral part of Islamic teaching. It also has legal implications for the Muslim treatment of followers of other religions. Of course, such classifications express an implied judgment , not only on Protestants, Jews, Roman Catholics, and Muslims, but all religions. This judgemental nature arises from the loyalties that exist in every society and religious culture. It is human nature for people to defend their own “tribe,” and by association decry other “tribes.” In the field of psychology, it is stated that in the religious person, emotions such as wonder, awe, and reverence are exhibited. Religious people tend to show concern for values – moral and aesthetic – and to seek out actions that have these values. They will be likely to characterize behaviour not only as good or evil but also as holy or unholy, and people as virtuous or un-virtuous, even godly or ungodly. 30
  • 31. The Greek philosopher Plato saw that in performing every good act, humans realize their link with eternity and the idea of goodness. He likened the human condition to the image of a man in a cave, chained by his earthly existence so that he cannot see the light outside, only the shadows on the wall. In order to see the light, man has to throw off his chains and leave the cave. The future of religion There is a universality contained in the answers, from whichever source one goes to, to the question, “what is the future of religion?” In essence, the respondents advised that a considerable increase of mutual understanding around the world needs to come about – an understanding that the earth is occupied by a vast number of people with an equally vast number of beliefs, and respect should be paid to all. The philosophy of the Golden Rule is implicit in virtually every religion. It is well known that in times of trouble, either personal, national, or international, that the number of people who embrace a religion increases. It could, therefore, be said that as trouble isn’t going to go away, neither is religion. Both are here to stay. 31
  • 32. LECTURES 11 and 12: Philosophy of ethics Ethics, our concern, deals with what is right or wrong in human behaviour and conduct. It asks such questions as what constitutes any person or action being good, bad, right, or wrong, and how do we know (epistemology)? What part does self-interest or the interest of others play in the making of moral decisions and judgements? What theories of conduct are valid or invalid, and why? Should we use principles or rules or laws, or should we let each situation decide our morality? Are killing, lying, cheating, stealing, and sexual acts right or wrong, and why or why not? The word itself ethics comes from the Greek ethos, meaning character. Morality comes from the Latin moralis, meaning customs or manners. Ethics, then, seems to pertain to the individual character of a person or persons, whereas morality seems to point to the relationships between human beings. Nevertheless, in ordinary language, whether we call a person ethical or moral, or an act unethical or immoral, does not really make any difference. In philosophy, however, the term ethics also is used to refer to a specific area of study: the area of morality, which concentrates on human conduct and human values. When we speak of people as being moral or ethical, we usually mean that they are good people, and when we speak of them as being immoral or unethical, we mean that they are bad people. When we refer to certain human actions as being moral, ethical, immoral, and unethical, we mean that they are right or wrong. The simplicity of these definitions, however, ends here, for how do we define a right or wrong action or a good or bad person? What are the human standards by which such decisions can be made? These are the more difficult questions that make up the greater part of the study of morality. One important thing to remember here is that moral, ethical, immoral, and unethical, essentially mean good, right, bad, and wrong, often depending upon whether one is referring to people themselves or to their actions. Approaches to ethics and morality Scientific, or descriptive approach There are two major approaches to the study of ethics and morality. The first is scientific, or descriptive. This approach most often is used in the social sciences and, like ethics, deals with human behaviour and conduct. The emphasis here, however, is empirical; that is, social scientists observe and collect data about human behaviour and conduct and then draw certain conclusions. For example, some psychologists, after having observed many human beings in many situations, have reached the conclusion that human beings act in their own self-interest. This is a descriptive, or scientific, approach to human behaviour – the psychologists have observed how human beings act in many situations, described what they have observed, and drawn conclusions. However, they make no value judgements as to what is morally right or wrong, nor do they describe how humans ought to behave. Philosophical approach The second major approach is called the philosophical approach, and consists of two parts. 32
  • 33. The first part of the philosophical approach to the study of ethics is called metaethics or, sometimes, analytic ethics. Rather than being descriptive or prescriptive, this approach is analytic in that it analyzes ethical language (for example, what we mean when we use the word good), the rational foundations of ethical systems and the logic and reasoning of various ethicists. Like metaphysics, metaethics refers to areas not directly related but somehow beyond (meta) the main subject-matter. Metaethicists do not prescribe anything, nor do they deal directly with normative systems. This means that metaethics has little to do with the real business of ethics, which is concerned with the ancient question “What is the good life?, or “What is the good?” or, in more modern terms, “How should I live my life?”, or “How should I solve this moral dilemma? Because it concerns only indirectly with normative ethical systems by concentrating instead on reasoning, logical structures, and language rather than content, it gives no answer to any of the above questions. In methaethics, a different set of questions are asked: questions about the nature of ethical thinking and ethical language; about what is meant by such things as free will, and whether we can be said to possess it; about what is meant by term such as “relative” and “absolute; and so on. Metaethics questions whether we can legitimately speak of objective ethical truth, or whether ethical convictions are merely the expressions of the individual’s inner feelings. The latter is called emotivism, which is the view that ethical convictions can only be expressed in terms of one’s feelings or attitudes, but cannot possibly be explained or justified. The former is called intuitionism because it holds that ethical convictions can be directly intuited, sensed or grasped, but again not explained. However, unlike emotivism, intuitionism at least opens the debate about what in the objective world makes us intuit goodness and evil, right and wrong. It should be noted here that metaethics, although always used to some extent by all ethicists, has become the sole interest of many modern ethical philosophers. This may be due in part to the increasing difficulty of formulating a system of ethics applicable to all or even most human beings. Our world, our cultures, and our lives have become more and more complicated and pluralistic, and finding an ethical system that will undergird all human beings’ actions is a difficult if not impossible task. Therefore, these philosophers feel that they might as well do what other specialists have done and concentrate on language and logic rather than attempt to arrive at ethical systems that will help human beings live together more meaningfully and ethically. The second part of the philosophical approach to the study of ethics deals with norms (or standards) and prescriptions. For this reason, it is called normative, or prescriptive, or substantive ethics. Normative ethics attempts to answer the fundamental practical questions of ethics and is the main concern of this philosophy course. The ethical theories that attempt to answer the questions of “What we ought to do”, and “How we ought to live” and make up the more abstract part of what is known as normative ethics – that is, the part of ethics concerned with guiding action will be discussed in the following lectures. The theories with which we will be dealing are: Ethical relativism in its two versions, i.e., subjective and conventional ethical relativism; Ethical objectivism in its many forms such as Ethical egoism, Utilitarianism, Kantian ethics, Virtue ethics. The application of ethical reasoning to specific areas of practical concern, i.e. applied ethics can be seen as the more practical counterpart or application of some of the theories of normative ethics. Areas of practical concern are for example: Euthanasia, Abortion, Punishment, Environmental ethics, etc. The origins of ethics One further consideration about the organization of this course. Before dealing with subjective ethical relativism, I begin with reading Plato’s dialogue called the Crito in which two famous 33
  • 34. ancient Athenians Crito and Socrates are engaged in a moral argument about what is the right course of action in a particular situation. In 399 B.C., Socrates was brought to trial on a charge of corrupting the young and introducing new divinities. He was found guilty and sentenced to death. The moral issue discussed in this dialogue is whether should Socrates accept the help and advise of his friend Crito and escape from jail. The two friends discuss what is the right course of action from a moral point of view. Why to choose such a remote starting-point for an introductory course of ethics? Because Socrates’ arguments for not escaping have inspired much of Western ethical thought and Plato’s dialogue the Crito is a classical example of ethical thinking and one of the earliest surviving treatises on philosophical ethics. There is a compelling reason for starting with a Greek writer. Ethics itself, as a form of intellectual enquiry, at least in the West, begins with the Greeks. In the thought of the Greek philosophers we can trace the beginnings of philosophical reflection on the nature of the good life and right conduct. The core of the ethical systems of both Plato and Aristotle is the attempt to justify the virtues in terms of human happiness, to show that they are good qualities to possess, because a life lived in accordance with the virtues is the happiest and most rewarding kind of life. Questions to be answered: (1) Identify Crito’s arguments and Socrates’ counter-arguments; (2) Identify the major principles held by each of the two; (3) Decide how valid their arguments are; (4) Decide whether Socrates took the right decision; (5) Tell what you would have done had you been in his position explaining the reasons for your choice. The main ethical theories Premises. I will start today’s lecture from a general but fundamental premise: It is important that all customs, traditions, systems of ethics, rules, and of course ethical theories, our main concern today, should be carefully analyzed and critically evaluated before we continue to accept or live by them. That is to say, we should not reject them out of hand, but neither should we endorse them wholeheartedly, unless we have subjected them to careful, logical scrutiny. For this reason, throughout this course and most importantly on your own in your own life, you are strongly encouraged to be reflective when dealing with morality and moral issues. But before going on to discuss the main ethical theories, there is another matter that I think it ought to be clarified preliminarily. It is important that we use reflection to distinguish morality from another area of human activity and experience with which it is often confused and of which it is often considered a part: religion. Because normative ethics seeks to establish principles that prescribe what we ought or ought not to do, it has in fact some similarities with another of the domains of human existence that seek to guide behaviour, i.e., religion. And in fact, many people think that religion and ethics not overlap but that they are inseparable. Furthermore, it is a historical fact that religion is deeply bound up with morality. It would be hard, if not impossible, to find an established religious tradition that does not contain extensive ethical teachings. In fact, some of the great religions of the world, such as Buddhism and Confucianism, are primarily ethical outlooks on life rather than doctrines about a deity. 34
  • 35. However, many philosophers (even religious ones) think that a sound ethical theory can be developed independently of religious assumptions. Furthermore, they argue that there are problems with divine command theories, i.e., with theories making the rightness or wrongness of an action intrinsically related to the fact that God either commands it or forbids it. The first problem is the lack of agreement as to which religious text or authority should guide our ethical deliberations: The Bible, for example, or the Koran, The Hindu Upanishads, Buddha’s teachings, and so on. To successfully live together in the same society, we need to arrive at some common ethical norms. But how can we do this in pluralistic societies where there is no agreement as to which religious authority (if any) should be followed? Furthermore, how can people be held ethically accountable for their behaviour if many have never been exposed to whatever religious tradition is supposed to be normative? The second problem is that even if we agree to live under the guidance of a particular religious tradition, we may disagree as to how to interpret its teachings. For example, Christians both defend and attack capital punishment on the basis of the same tradition and sacred texts. Similarly, while the Bible often condemns lying, it contains passages in which God is said to reward people for lying on his behalf and even commands individuals to lie. [Note: For Biblical approval of specific acts of lying, see Exodus 1:15-20 and Joshua 2:1-6 (in conjunction with Hebrews 11:31). For divinely commanded lying, see 1 Samuel 16:1-3.] Minimally, some sort of philosophical reflection is necessary to sort out all these discrepancies. Third, some ethical questions cannot be answered by traditional religious teachings apart from philosophical considerations. Is it morally acceptable to make cloned duplicates of humans? When numerous people need an organ transplant or a kidney dialysis machine but the medical supplies are scarce, what is the just way to allocate these resources? To what extent do journalists have an obligation to serve the public’s right to know and to what extent do they have an obligation to protect individual’s privacy? Most religious traditions are clear on ethical topics such as adultery, murder, and stealing, but many ethical dilemmas in contemporary society are not addressed by these traditions. These considerations suggest that whatever ethical guidance someone may find in a particular religious tradition, everyone need to engage in philosophical reflection on ethics based on human experience and reason and not merely on authority or tradition. The main ethical theories I. Ethical relativism is the position that there are no objective or universally valid moral principles, for all moral judgments are simply a matter of human opinion. This position comes in two versions: (a) Subjective ethical relativism the doctrine that what is right or wrong is solely a matter of each individual’s personal opinion. Just as some people like the colour purple and some detest it, and each person’s judgement on this matter is simply a matter if his individual taste, so there is no standard other than each person’s own opinion when it comes to right or wrong. This doctrine implies that it is impossible for an individual to be mistaken about what is right or wrong. (b) Conventional ethical relativism (conventionalism) refers to the claims that morality is relative to each particular society or culture. For example, whether it is moral for women to wear shorts is a question of whether you are talking about mainstream American society or the Iranian culture. In other words, there are no universal objective moral standards that can be used to evaluate the ethical opinions and practices of a particular culture. This doctrine implies that it is impossible for a society to be mistaken about what is right or wrong. Questions: 35
  • 36. - Do you believe that the fact that people disagree about what is good or right is a good reason to support ethical relativism? - In what ways do you think that science is different from ethics? Are they alike in any ways? For example, do they both involve being impartial and nonbiased? - Is there an objective good, do you think that it is likely to be unitary or plural? For example, is it likely that all morality will be a function of the promotion of one ultimate good, such as happiness? Or is it more likely that there are many moral values, such as happiness, autonomy, privacy, and fidelity, which are each equally good and not reducible to the others? - Suppose that no matter how long reasonable people continued their deliberations, they would converge only on some principles, but not all. What would follow about the nature of moral objectivity, defined in terms of reasonableness? Does what follows constitute a problem for the account of objectivity? Can you propose a better account? II. Ethical objectivism is the view that there are universal and objectively valid moral principles that are relative neither to the individual nor to society. Because objectivism is a very general doctrine that covers a wide range of more specific ethical theories, various objectivists will differ as to what the correct moral principles are and how we can know them. Nevertheless, they all agree that in every concrete situation there are morally correct and morally wrong ways to act. Furthermore, they would agree that if a certain action in a given situation is morally right or wrong for a particular person, then it will be the same for anyone who is relevantly similar and facing relevantly similar circumstances. Ethical objectivism implies that it is possible for an individual or an entire society to sincerely believe that their actions are morally right at the same time that they are deeply mistaken about this assumption. The next eight theories all fall under the heading of ethical objectivism. Although these theories disagree about what ethical principles should be followed, they all agree that there are one or more non-arbitrary, non-subjective, universal moral principles that determine whether an action is right or wrong. 36
  • 37. Schedule of readings and assignments (some changes are possible during the course): (1) Introduction: What is philosophy? Reading: Fundamentals of Philosophy, “Socrates: In Defence of Philosophy”, pp.17-25. (2) The basic concepts of logic I: Deductive arguments. Reading: Ibid, pp.56-69. (3) The basic concepts of logic II: Inductive arguments. Reading: Ibid, pp.70-79. (First assignment.) (4) Theory of knowledge: Rationalism, empiricism and Kantian criticism. Reading: “Immanuel Kant: Two Sources of Knowledge”, Ibid, pp.235-239. (5) Metaphysics: The search for the ultimate reality. Reading: “Plato: The Visible and the Invisible”, Ibid, pp.109-119. (6) The search for God . Reading: “Arguments for God’s Existence: The Ontological Argument”, Ibid, pp.338-350. (Second assignment) (7) The search for ethical values. Reading: “Thomas Hobbes: Leviathan”, Ibid, pp.267-280. (8) The search for the just society. Reading: “John Rawls: A Theory of Justice”, in Ibid., pp.477-485. (9) Philosophy of Art. Reading: “A.C. Bradley: Poetry for Poetry’s Sake”, Ibid., pp.421-430. (Third assignment) (10) Philosophy East and West. Reading: Ibid., pp.489-499. (11) Eastern Thought: Hinduism and Buddhism. Reading: “Setting in Motion the Wheel of Truth: Dhammacakkappavattana-sutta (The First Sermon of the Buddha)”, Ibid., pp.431-433. (12) Eastern Thought: Confucianism and Taoism. Reading: “Lao Tzu: The Tao Te Ching”, in Ibid., pp.548-550. (Final assignment) Grading Scale: 4=A 3.67=A- 3.33=B+ 3.00=B 2.67=B- 2.33=C+ 2.00=C 2.67=C- 1.33=D+ 1.00=D 0.67=D- 0=F Weight of assignments: Four assignments will be given, each counting 25% Assignment 1 (1A) (1B) Due at the end of the third week of the course (The other assignments will be given during the lectures) • (1A) 50% (12,5% of final mark) In about 400 words answer the following question: What is the practical value of philosophy? • (1B) 50% (12,5% of final mark) In about 400 words answer the following question: Argument and evidence: How do I decide what to believe? 37
  • 38. Late papers will be lowered one grade for each calendar day (except Saturdays and Sundays) that they are late. Class participation Class participation and attendance are strongly recommended because they are crucial to success in this course, for this reason not more than 3 absences are allowed (i.e., with 4 absences a student automatically forfeits the class). Academic misconduct and plagiarism Academic misconduct and plagiarism will be dealt with according to the regulations set by the Ohio University Undergraduate Catalogue 2002-2003. 38