Critical Thinking Chapter 5 Logical Fallacies I Fallacies

Critical Thinking Chapter 5 Logical Fallacies I Fallacies of Relevance Lecture Notes © 2008 Mc. Graw Hill Higher Education 1

Definitions o o o Logical Fallacy (or fallacy): an argument that contains mistake in reasoning. Fallacy of Relevance: the premises are logically irrelevant to the conclusion. Relevance: A statement is relevant to another statement if it would, if true, provide at least some evidence that the second statement is true or false. Lecture Notes © 2008 Mc. Graw Hill Higher Education 2

Fallacies of Relevance 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Personal Attack (ad Hominem) Attacking the Motive Look Who’s Talking (Tu Quoque) Two Wrongs Make a Right Scare Tactics Appeal to Pity Bandwagon Argument Straw Man Red Herring Equivocation Begging the Question Lecture Notes © 2008 Mc. Graw Hill Higher Education 3

1 Personal Attack (Ad Hominem) o This is the fallacy that dismisses an argument by attacking the person that made the argument. n e. g. , Thaksin condemned the military coup. But he is corrupt. Therefore, his argument is worthless. Lecture Notes © 2008 Mc. Graw Hill Higher Education 4

2 Attacking the Motive o The error of criticizing a person’s motivation. n e. g. , Jeff Miron has argued against road tax. But of course he does, he is a driver. Lecture Notes © 2008 Mc. Graw Hill Higher Education 5

3 Look Who’s Talking (Tu Quoque) o …rejects another person’s argument because that person fails to “practice what they preach. ” n e. g. , I don’t need to stop smoking just because my doctor tells me to; he smokes even more! Lecture Notes © 2008 Mc. Graw Hill Higher Education 6

4 Two Wrongs Make a Right o Tries to make a wrong action look right, by comparing it to another wrong action. n e. g. , We don’t feel guilty about money printing; Ben Bernanke does it. Lecture Notes © 2008 Mc. Graw Hill Higher Education 7

5 Scare Tactics o Threatens harm if he or she does not accept the argument's conclusion and this threat is irrelevant. n e. g. , This debt ceiling bill is wrong for America, and Obama who supports it will discover how wrong he is at the next election. Lecture Notes © 2008 Mc. Graw Hill Higher Education 8

6 Appeal to Pity o …attempts to evoke feelings of pity or compassion from his listeners or readers. n e. g. , You shouldn’t give me an F in Critical Thinking because I’ve failed all the exams; I really had a rough semester. Lecture Notes © 2008 Mc. Graw Hill Higher Education 9

7 Bandwagon Argument o . . . plays on a person’s desire to be popular, accepted, or valued. n e. g. , Everyone who is cool carries an i. Pad 3. So you should too. Lecture Notes © 2008 Mc. Graw Hill Higher Education 10

8 Straw Man o …distorts an opponent’s argument to make it weak (like a straw man). n n e. g. , Bob argued that we should outlaw violent pornography. Obviously he is against free-speech. No one should take him seriously. This “re-casts” the plausible “antiviolent pornography” argument as not-so-plausible “anti free-speech” argument. Lecture Notes © 2008 Mc. Graw Hill Higher Education 11

9 Red Herring o …tries to sidetrack his audience by raising an irrelevant issue and then claims that the original issue has effectively been settled. n e. g. , Many people criticize Bush for attacking Iraq. But he was one of our greatest presidents. Such criticisms must be unfounded. Lecture Notes © 2008 Mc. Graw Hill Higher Education 12

10 Equivocation (Make things ambiguous) o When it “switches the meaning” of one or more of its ambiguous terms. n e. g. , (1) Any law can be repealed. (2) So the law of gravity must be able to be repealed. Lecture Notes © 2008 Mc. Graw Hill Higher Education 13

11 Begging the Question o …one assumes, as a premise, the very thing that is one’s conclusion. n e. g. , Capital punishment is wrong because it is ethically impermissible to inflict death as punishment for a crime. Lecture Notes © 2008 Mc. Graw Hill Higher Education 14

Tutorial o o All marked ones 5. 1, 5. 2 Lecture Notes © 2008 Mc. Graw Hill Higher Education 15