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

Lecture Notes © 2008 McGraw Hill Higher Education© 2008 McGraw Hill Higher Education 2 Definitions  Logical Fallacy (or fallacy): an argument that contains mistake in reasoning.  Fallacy of Relevance: mistakes in reasoning that occur because 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 McGraw Hill Higher Education© 2008 McGraw Hill Higher Education 3 Fallacies of Relevance 1. Personal Attack (ad Hominem) 2. Attacking the Motive 3. Look Who’s Talking (Tu Quoque) 4. Two Wrongs Make a Right 5. Scare Tactics 6. Appeal to Pity 7. Bandwagon Argument 8. Straw Man 9. Red Herring 10. Equivocation 11. Begging the Question

Lecture Notes © 2008 McGraw Hill Higher Education© 2008 McGraw Hill Higher Education 4 Personal Attack (Ad Hominem)  This is the fallacy that dismisses an argument by attacking the person that made the argument, rather than attacking the claims themselves. e.g., Thaksin argued against the military coup. But he is corrupt. Therefore, his argument is worthless.

Lecture Notes © 2008 McGraw Hill Higher Education© 2008 McGraw Hill Higher Education 5 Attacking the Motive  The error of criticizing a person’s motivation for offering a particular argument or claim. e.g., Jeff Miron has argued against road tax. But of course he does, he is a driver.

Lecture Notes © 2008 McGraw Hill Higher Education© 2008 McGraw Hill Higher Education 6 Look Who’s Talking (Tu Quoque)  …when an arguer rejects another person’s argument or claim because that person fails to “practice what they preach.” e.g., I don’t need to stop smoking just because my doctor tells me to; he smokes and won’t stop either!

Lecture Notes © 2008 McGraw Hill Higher Education© 2008 McGraw Hill Higher Education 7 Two Wrongs Make a Right  This fallacy is committed when one tries to make a wrong action look right, by comparing it to another wrong (perhaps worse) action. e.g., We don’t feel guilty about money printing; Ben Bernanke does it.  However, sometimes actions can be justified by the fact that other actions have taken place. e.g., Ip Man side-kicked the man because he was about to hit him; it was an act of self-defense.

Lecture Notes © 2008 McGraw Hill Higher Education© 2008 McGraw Hill Higher Education 8 Scare Tactics  This fallacy is committed when an arguer threatens harm to a reader if he or she does not accept the argument's conclusion and this threat is irrelevant to the truth of the conclusion. 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 McGraw Hill Higher Education© 2008 McGraw Hill Higher Education 9 Appeal to Pity  …occurs when an arguer inappropriately attempts to evoke feelings of pity or compassion from his listeners or readers. e.g., You shouldn’t give me an F in the class just because I failed all the exams; I had really rough semester.

Lecture Notes © 2008 McGraw Hill Higher Education© 2008 McGraw Hill Higher Education 10 Bandwagon Argument ...an argument that plays on a person’s desire to be popular, accepted, or valued. e.g., Everyone who is cool carries an iPad. So you should too.

Lecture Notes © 2008 McGraw Hill Higher Education© 2008 McGraw Hill Higher Education 11 Straw Man  …fallacy is committed when an arguer distorts an opponent’s argument to make it weak (like a straw man) and thus easier to attack. 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 “anti-violent pornography” argument as not-so-plausible “anti free-speech” argument.

Lecture Notes © 2008 McGraw Hill Higher Education© 2008 McGraw Hill Higher Education 12 Red Herring  …is committed when an arguer tries to sidetrack his audience by raising an irrelevant issue and then claims that the original issue has effectively been settled by the irrelevant diversion. 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 McGraw Hill Higher Education© 2008 McGraw Hill Higher Education 13 Equivocation  An argument commits the fallacy of equivocation when it “switches the meaning” of one or more of its ambiguous terms. e.g., (1) Any law can be repealed. (2) So the law of gravity must be able to be repealed.

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

Lecture Notes © 2008 McGraw Hill Higher Education© 2008 McGraw Hill Higher Education 15 Tutorial  All marked ones  5.1, 5.2