Week 3

1. LOGICProf Roy Shaff Week 3 1

2. Key Terms for Ch 4

3. Objectives 3 When you complete this lesson, you will be able to recognize: Fallacies of relevance Fallacies of defective induction Fallacies of presumption Fallacies of ambiguity

4. What is a Fallacy? 4 A type of argument that may seem to be correct but contains a mistake in reasoning Known to be deceptive YouTube - Monty Python - Argument Clinic

5. The Classifications of Fallacies 5 Fallacies of relevance Premises are simply not relevant to the conclusion drawn Fallacies of defective induction Premises of the argument are so weak and ineffective that reliance upon them is wrong Fallacies of presumption Too much has been assumed in the premises Fallacies of ambiguity Use of words or phrases where a critical term has different senses in different parts of the argument

6. Fallacies of Relevance 6 Appeal to emotion Relies on expressive language and other devices calculated to excite enthusiasm for or against some cause in place of evidence and rational argument YouTube - Advertising Fallacies

7. Fallacies of Relevance, continued 7 Appeal to pity Argument relies on generosity, altruism, or mercy, rather than reason http://www.youtube.com/watch?v=7-YpcrJEe78

8. Fallacies of Relevance, continued 8 Appeal to force Argument relies on the threat of force The threat may be veiled

9. Fallacies of Relevance, continued 9 Argument against the person (argument ad hominem) Argument relies on character assassination of the individual taking the opposing position Abusive Denies opponent’s intelligence, reasonableness, seriousness, or integrity Circumstantial Opponent is obliged to accept or reject some conclusion merely because of employment, nationality, political affiliation, or other circumstances

10. Fallacies of Relevance, continued 10 Irrelevant conclusion The premises go in one direction, and the conclusion goes in another direction Straw man The opponent’s position is misrepresented YouTube - The "Straw Man" Fallacy Red herring A distracting element is introduced to obscure an opponent’s position YouTube - The "Red Herring" Fallacy Non sequitor (“does not follow”)is a term often applied to irrelevant conclusions

11. Fallacies of Defective Induction 11 Argument from ignorance (argument ad ignorantiam) Proposition is held to be true just because it is not been proved false, or false just because it has not been proved true

12. Fallacies of Defective Induction, continued 12 Appeal to inappropriate authority Conclusion is based on the judgment of a supposed authority who has no legitimate claim to expertise in the matter

13. Fallacies of Defective Induction, continued 13 False cause Something that is not really a cause is treated like a cause Fallacy of post hoc ergo propter hoc “After the thing, therefore because of the thing” Slippery slope Any change in a particular direction is sure to lead to further changes in the same direction, and on to grave consequences http://www.youtube.com/watch?v=DtmAw9Ia7LA

14. Fallacies of Defective Induction, continued 14 Hasty generalization (converse accident) Moving carelessly from individual cases to generalization A leap is made to a broad generalization on the basis of very little evidence

15. Fallacies of Presumption 15 Accident Opposite of hasty generalization Moving carelessly or unjustifiably from a generalization to some particulars that it does not cover in fact

16. Fallacies of Presumption, continued 16 Complex question A question is asked in a way that presupposes the truth of some proposition buried within the question

17. Fallacies of Presumption, continued 17 Begging the question (petitioprincipii) Conclusion is stated or assumed within one of the premises Circular argument http://www.youtube.com/watch?v=YoOd7QfRW5s

18. Fallacies of Ambiguity 18 Equivocation Two or more meanings of a word or phrase are used in different parts of an argument Use of relative terms http://www.youtube.com/watch?v=sShMA85pv8M

19. Fallacies of Ambiguity, continued 19 Amphiboly Loose or awkward combination of words can be interpreted more than one way Argument contains a premise based on one interpretation while the conclusion relies on a different interpretation

20. Fallacies of Ambiguity, continued 20 Accent Phrase is used to convey two different meanings within an argument, and the difference is based on changes in emphasis given to the words within the phrase

21. Fallacies of Ambiguity, continued 21 Composition Inference is drawn mistakenly from the attributes of the parts to the attributes of the whole Reasoning fallaciously from the attributes of the parts of a whole to the attributes of the whole itself Reasoning from attributes of the individual elements or members of a collection to attributes of the collection or totality of those elements

22. Fallacies of Ambiguity, continued 22 Division Inference is drawn from the attributes of a whole to the attributes of the parts Arguing fallaciously that what is true of a whole must be true of its parts Arguing from the attributes of a collection of elements to the attributes of the elements themselves

23. Case Study 23 YouTube - CAS 100B - 12 Angry Men clips

24. Summary 24 Fallacies of relevance Fallacies of defective induction Fallacies of presumption Fallacies of ambiguity