CHAPTER 7

1. CHAPTER 7 LOGICAL FALLACIES

2. INTRODUCTION • We encounter arguments all over the place, in books, advertisement, TV talk shows, political speeches, newspaper editorials and class discussion. • Some of those arguments are sound and convincing but many fallacious. • Definition of Fallacy: • An error in reasoning that renders an argument invalid (unacceptable/illogical).

3. An argument is fallacious when it contains one or more logical fallacies. • A logical fallacy is an argument that contains a mistake in reasoning. • There are many common logical fallacies and they can be classified in various way. • The simplest way is by dividing the logical fallacies into two different groups: • Fallacies of relevant • Fallacies of insufficient evidence

4. Fallacies of relevance • Mistakes in reasoning that occur because the premises are logically irrelevant to the conclusion. • Fallacies of insufficient evidence • Mistakes in reasoning that occur because the premises though logically relevant to the conclusion, fail to provide sufficient evidence to support the conclusion.

5. THE CONCEPT OF RELEVANCE • A statement is relevant to another statement if it provides at least some evidence or reason for thinking that the second statement is true or false. • There are 3 ways in which a statement can be relevant or irrelevant to another. A statement can be: • Positively relevant • Negatively relevant • Logically irrelevant

6. 1. Positively Relevant • A statement is positively relevant to another statement if it counts in favor of that statement. • E.g.: • First argument: Dogs are cats. Cats are felines. So dogs are felines. • Second argument: All dogs have five legs. Rover is a dog. So Rover has five legs.

7. Each of these premises is positively relevant to its conclusion, that is each provides at least some reason for thinking that the conclusion is true. • In the first and second arguments, the premises provide logically conclusive reasons for accepting the conclusion.

8. 2. Negatively Relevant • Statement that count against other statements are said to be negatively relevant to those statements. • E.g.: • First argument: Marty is a high school senior. So, Marty likely has a Ph.D. • Second argument: Althea is two years old. So, Althea probably goes to college.

9. In both of these examples, the premises are negatively relevant to the conclusion. • Each premise, if true provides at least some reason for thinking that the conclusion is false.

10. 3. Logically Irrelevant • A statement is logically irrelevant to another statement if it counts neither for nor against that statement. • E.g.: • First argument: The earth revolves around the sun. Therefore, marijuana should be legalized. • Second argument: Last night I dreamed that the Yankees will win the pennant. Therefore, the Yankees will win the pennant.

11. Neither of these 2 premises provides the slightest reason for thinking that its conclusion is either true or false. • Thus, they are logically irrelevant to those conclusions.

12. FALLACIES OF RELEVANCE • A fallacy of relevance occurs when an arguer offers reasons that are logically irrelevant to his or her conclusion. • Fallacies of relevance often seem to be good arguments but aren’t.

13. 1. PERSONAL ATTACK • Arguer attacks the character of another arguer • We commit the fallacy of personal attack when we reject someone’s argument or claim by attacking the person rather than the person’s argument or claim. • E.g.: • Hugh Hefner is a bad person. • Therefore, Hugh Hefner’s argument must be bad.

14. But the pattern of reasoning is clearly fallacious. Even if it is true that Hefner is a bad person, that doesn’t mean he is incapable of offering good arguments.

15. However, not every personal attack is a fallacy. The fallacy of personal attack occurs only if an arguer attacks the person who offers the arguments or claims rather than considering the merits of that arguments or claim. • E.g.: • Becky Fibber has testified that she saw my client rob the First National Bank. But Ms. Fibber has twice been convicted of perjury. In addition, you’ve heard Ms. Fibber own mother testify that she is pathological liar. Therefore, you should not believe Ms. Fibber’s testimony against my client. • Here the issue is whether Ms. Fibber is or is not a believable witness. Because the arguer’s personal attack is relevant to this issue, no fallacy is committed.

16. 2. ATTACKING THE MOTIVE • Arguer attacks the motive of another arguer • The error of criticizing a person’s motivation for offering a particular argument or claim, rather than examining the worth of the argument or claims itself. • E.g. • Mr. Max is biased or has questionable motives. • Therefore, Mr. Max’s argument or claim should be rejected.

17. The pattern of reasoning is fallacious because people with biases or questionable motives do sometimes offer good arguments. • We cannot simply assume that because a person that has a vested interest in an issue that any position he or she takes on the issue must be false or weakly supported.

18. However, not all attacks on an arguer’s motivates are fallacious. • E.g.: • Burton Wexler, spokesperson for the American Tobacco Growers Association has argued that there is no credible scientific evidence that cigarette smoking causes cancer. Given Wexler’s obvious bias in the matter, his argument should be taken with a grain of salt.

19. 3. LOOK WHO’S TALKING • Arguer attacks the hypocrisy of another arguer • Look who’s talking is committed when an arguer rejects another person’s arguments or claim because that person fails to practice what he preaches. • E.g.: • Doctor Carl fails to follow his own advice to quit smoking. • Therefore, Doctor Carl’s claim or argument should be rejected.

20. Arguments are good or bad not because of who offers them but because of their own intrinsic strengths or weaknesses. • We cannot refute a person’s argument simply by pointing out that he or she fails to practice what he or she preaches.

21. 4. TWO WRONGS MAKE A RIGHT • Arguer tries to justify a wrong by citing another wrong • Occurs when an arguer attempts to justify a wrongful act by claiming that some other act just as bad or worse. • E.g.: • I don’t feel guilty about cheating on Mr. Alex’s test. Half the class cheats on his test. • This argument commits a fallacy of two wrong make a right because it attempts to justify a wrongful act by citing another wrongful act.

22. 5. SCARE TACTICS • Arguer threatens a reader or listener. • The fallacy of scare tactics is committed when an arguer threatens a reader or listener. • Fear is a powerful motivator that it often causes us to think and behave irrationally. • E.g.: • If this man gets elected, he’ll change your welfare benefits.  Don’t let those Washington bureaucrats tinker with your food stamps!”

23. 6. APPEAL TO PITY • Arguer tries to evoke pity from a reader or listener. • Occurs when an arguer inappropriately attempts to evoke feelings of pity or compassion from his listeners or readers. • E.g.: • Student to Professor: I know I missed your classes and failed all my exams, but I had a really tough semester. First, my pet boa constrictor died. With all I went through this semester, I don’t think I really deserved an F. Any chance you might cut me some slack and change my grade to a C or D?

24. This argument may or may not be effective in arousing our sympathies. • Logically, however, the argument are clearly fallacious because the premise provide no relevant reasons to accept the conclusions.

25. 7. BANDWAGON ARGUMENT • Arguer appeals to a reader’s or listener’s desire to accepted or valued. • A bandwagon argument is one that plays on a person’s desire to be popular, accepted or valued rather than appealing to logically relevant reasons or evidence. • E.g.: • All the really cool kids at East Jefferson High School smoke cigarettes. Therefore, you should too.

26. This pattern is fallacious because the fact that a belief or practice is popular usually provides little or no evidence that the belief is true or that the practice is good.

27. 8. STRAW MAN • Arguer misrepresents an opponent’s position. • Straw man fallacy is committed when an arguer distorts an opponent’s argument or claim to make it easier to attack. • E.g.: • Peter’s view is false or unjustified (but where Peter’s view has been unfairly characterized or misrepresented.) • Therefore, Peter’s view should be rejected. • Clearly, argument of this pattern provide no logically relevant support for their conclusions.

28. 9. RED HERRING • Arguer tries to distract the attention of the audience by raising an irrelevant issue. • A red herring is a fallacy in which an irrelevant topic is presented in order to divert attention from the original issue. The basic idea is to "win" an argument by leading attention away from the argument and to another topic.

29. E.g.: • Topic A is under discussion. • Topic B is introduced under the guise of being relevant to topic A (when topic B is actually not relevant to topic A). • Topic A is abandoned. • This sort of "reasoning" is fallacious because merely changing the topic of discussion hardly counts as an argument against a claim.

30. 10. EQUIVOCATION • A fallacy by which a key word or phrase in an argument is used with more than one meaning. • E.g.: • It is a crime to smoke grass. Kentucky bluegrass is a grass. Therefore, it is a crime to smoke Kentucky bluegrass. • A key word is used ambiguously or equivocally that is, with two or more distinct sense. This argument equivocates on the word grass. In the first premise, it means marijuana but in the second it means ordinary lawn grass.

31. 11. BEGGING THE QUESTION • Arguer assumes the point to be proven. • Committed when a person merely assumes what he or she is attempting to prove or when the premise of an argument actually depends upon its conclusion. • E.g.: • Teacher: Did you believed in alien spaceships? And why? • Young student: “Of course. How else would the aliens get here?” • The aliens would never be able to get to earth without a spaceship. So, clearly, there must be alien spaceships!

32. In this case, the young student was attempting to prove the existence of alien spacecraft by taking it for granted that aliens have traveled to earth. • But that is essentially the point in question.