1. L i l F ll iLogical Fallacies
by Dr Karen Lee M F A Ph Dby Dr. Karen Lee, M.F.A., Ph.D.
The Writing Center
@ Vanguard University
of Southern California
“Faith and knowledge resting on the
hope of eternal life ” (NIV Titus 1 2)
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hope of eternal life . . . (NIV, Titus 1.2).

2. Grateful Acknowledgments
• Exercises are briefly excerpted from Classical• Exercises are briefly excerpted from Classical
Rhetoric for the Modern Student by Corbett, Edward
P.J. and Robert J. Connors. New York: Oxford
University Press 1999 (This textbook is used inUniversity Press, 1999. (This textbook is used in
our upper-division English course, ENG 370:
Advanced Rhetoric & Composition.)
• Short passages by H.L. Mencken and Herman
Melville are briefly excerpted from Dora Smith’sy p
anthology, American Experience: Nonfiction. New
York: MacMillan, 1984.
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3. Introduction
Getting to KnowGetting to Know
Logical FallaciesLogical Fallacies
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4. What’s a logical fallacy and
why should you care?why should you care?
• It’s poor logic partly consisting of
li ti d tiovergeneralizations and assumptions.
• The presence of logical fallacies may weaken a
iti j t Wh ’ d l iwriting project. When you’re developing an
argument, your points should follow in logical
order and make proper conclusionsorder and make proper conclusions.
• When you’re refuting a counterargument
(procatalepsis), it’s useful to point out logical(procatalepsis), it s useful to point out logical
fallacies as weak points in your opponent’s
argument.
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5. Logical Fallacies:
Several ExamplesSeveral Examples
• non sequitor: reasoning doesn’t hold together,
"doesn't follow“
• bandwagon: recommends a course of action
just because “everyone else” is doing it
• equivocation: ambiguity• equivocation: ambiguity
• either/or: false binaries
• faulty generalization: inadequate evidence &faulty generalization: inadequate evidence &
jumps to conclusions
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6. Logical Fallacies:
More ExamplesMore Examples
• faulty causal: cause & effect problem
• faulty analogy: analogy does not hold;
compared parts dissimilarp p
• begging the question: circular
reasoning & tautological definitionsreasoning & tautological definitions
• ad hominem: argument switches to
character slandercharacter slander
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7. Logical Fallacies:
Still More ExamplesStill More Examples
• ad populum: appeals to irrational fears
& j di& prejudices
• red herring: dodges main issue (refers
t d h i d d th thto red herring dragged across the paths
of hounds to throw them off in their
pursuit)pursuit)
• complex question: two-pronged
question "When did you stop stealing?"question When did you stop stealing?
(combines two questions, one implied)
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8. Now You Try It!
For the next group of slides, identify the
logical fallacy at work in each. You may
choose among these terms: non
sequitor, equivocation, faulty
generalization, bandwagon, faulty
causal, faulty analogy, begging the
question, ad hominem, ad populem,
red herring, and complex question.
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9. Identify Logical Fallacies
• “ ‘Either they voted for the candidate or
they voted for the candidate’s
opponent’ ” (Corbett and Connors 67).
• “Any man who is honest will not steal.Any man who is honest will not steal.
My client is honest. Therefore, my
client would not steal” (Corbett andclient would not steal (Corbett and
Connors 69).
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10. Answers
• “ ‘Either they voted for the candidate or they
voted for the candidate’s opponent’ ” (Corbettvoted for the candidate’s opponent’ ” (Corbett
and Connors 67).
EITHER/OR FALLACYEITHER/OR FALLACY
“A h i h t ill t t l M li t• “Any man who is honest will not steal. My client
is honest. Therefore, my client would not steal”
(Corbett and Connors 69)(Corbett and Connors 69).
BEGGING THE QUESTION
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11. Identify the Logical Fallacy
• “ ‘My opponent’s arguments are very
impressive, but remember, this is the
man who deserted his faithful wife
and family after he had won his first
political victory’ ” (Corbett and
Connors 70).
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12. Answer
• “ ‘My opponent’s arguments are very
impressive, but remember, this is the man
who deserted his faithful wife and family
after he had won his first political victory’ ”
(Corbett and Connors 70).
AD HOMINEMAD HOMINEM
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13. Identify Logical Fallacies
• “ ‘You accuse me of cheating on my
income tax, but doesn’t everybody
cheat a little bit’ ” (Corbett and
Connors 70)?
• “ ‘Why did you steal the diamond
ring’ ” (Corbett and Connors 71)?ring (Corbett and Connors 71)?
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14. Answers
• “ ‘You accuse me of cheating on my income tax, but
doesn’t everybody cheat a little bit’ ” (Corbett anddoesn t everybody cheat a little bit (Corbett and
Connors 70)?
RED HERRINGRED HERRING
OR FAULTY GENERALIZATION
• “ ‘Why did you steal the diamond ring’ “ (Corbett and
COMPLEX QUESTIONConnors 71)? COMPLEX QUESTION
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15. Detecting Logical Fallacies:
Examine this ExcerptExamine this Excerpt
“But it is not meant that all American
it h ld t di l l twriters should studiously cleave to
nationality in their writings; only this, no
American writer should write like anAmerican writer should write like an
Englishman or a Frenchman; let him write
like a man for then he will be sure tolike a man, for then he will be sure to
write like an American. Let us away with
this leaven of literary flunkeyism towardsy y
England” (Melville 275).
Melville, Herman. “Hawthorne and His Mosses.” American Experience: Nonfiction. Dora Smith, Gen. Ed.
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New York: MacMillan, 1984. 269-277.

16. Detecting Logical Fallacies:
Examine this ExcerptExamine this Excerpt
“Turn, now, to politics. Consider, for example, a campaign
more uproariously idiotic – a deafening, nerve-wracking
battle to the death between Tweedledum and Tweedledeebattle to the death between Tweedledum and Tweedledee,
Harlequin and Sganarelle, Gobbo and Dr. Cook – the
unspeakable, with fearful snorts, gradually swallowing the
inconceivable? I defy anyone to match it elsewhere on the
earth In other lands at worst there are at least intelligibleearth. In other lands, at worst, there are at least intelligible
issues, coherent ideas, salient personalities. Somebody
says something, and somebody replies. But what did
Harding say in 1920, and what did Cox reply? Who wasg y , p y
Harding, anyhow, and who was Cox? Here, having
perfected democracy, we lift the whole combat to symbolism,
to transcendentalism, to metaphysics. Here we load a pair
of palpably tin cannon with blank cartridges charged withof palpably tin cannon with blank cartridges charged with
talcum powder, and so let fly” (Mencken 388).
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Mencken, H. L. “On Being an American.” Dora Smith, Gen. Ed. American Experience: Nonfiction.
New York: MacMillan, 1984. 385-389.

17. Summary
• A logical fallacy is simply poor logic.
• The presence of logical fallacies may
weaken a writing project.
• It’s often useful to point out logical
fallacies as weak points in your
t’ topponent’s argument.
• Logical fallacies are usually forms of
i t ti bi j iinaccurate assumptions, bias, jumps in
thought, & overgeneralizations.
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Colossians 2.8

18. The Writing Center
For more help with logical fallacies,
contact the Writing Center.g
• Where: Heath 214
• What else: Thanks for your interest in our• What else: Thanks for your interest in our
resources!
“Faith and knowledge resting on the hope“Faith and knowledge resting on the hope
of eternal life . . .” (NIV, Titus 1.2).
Version Date: 3.10.06, klee@vanguard.edu,
Colossians 2.8