Informal Fallacies

1. Informal Fallacies • Defective reasoning that makes weak arguments appear stronger. • Tools of advertisers, propagandists, charlatans, and sincere yet self-deceived people who make claims without the benefit of good evidence. • Aristotle was the first thinker to begin to classify various types of defective inferences that provide psychologically persuasive (but not logically adequate) reasons to believe a claim.

2. Fallacious Assumptions • False Dilemma: Presenting two alternatives as the only ones when others are possible. • Either you accept every verse of Scripture as God’s word or reject it all as false human religious speculation. • If the glove does not fit, you must acquit!

3. Sneaky Assumptions • Complex question: Two questions asked as one to trap the unwary. • How long have you had the drinking problem? • When will Fox and CNN get out of bed with the Bush administration? • When will Obama stop lying about his birth certificate? • Innuendo: Saying one thing but suggesting something more negative. • Yes, he’s telling the truth, this time. • She’s competent in many ways. • He’s pretty bright, for a community college instructor.

4. Circular Reasoning • Begging the question: when the arguer assumes as a premise the conclusion he or she is arguing for. • Abortion is murder because it kills babies. • No affirmative action policy can be fair or just because you can’t fix one injustice by committing another. • We have to have the death penalty to keep murderers off our streets. • We must reject Obamacare. Government programs are never as effective as private enterprise.

5. Ambiguity Therefore, we have a duty to study logic • Equivocation: Shifting the meaning of an ambiguous term. • Knowledge is power. Power corrupts. Therefore, knowledge corrupts. We have the right to study logic. We have a duty to do right….

6. Ambiguous Phrasing: Amphibole • Dog for sale. It eats anything and is very fond of children. • If you don’t go to other people’s funerals, they won’t come to yours. • He is trying to quit smoking cold turkey. • Tired of cleaning yourself, let us do it for you. • False implication: When an advertiser says something true but implies something that isn’t true.

7. False Implication! Fruity Pebbles Captain Crunch Crunch Berries Country Time Lemonade The Navy, it’s not just a job, its an adventure. When you’re hungry, reach for a Snickers. You’ve come a long way, baby. Tylenol, the official supplier of pain relief products to the US Olympic team.

8. Composition and Division • Composition: Incorrectly inferring that what is true of the parts is true of the whole. • We have the best athletes in the league on our team, so we have the best team. • OxiClean is yours for just four easy payments of $19.95 • Division: Incorrectly inferring that what is true of the whole is true of the parts. • USC has a great school of business. Therefore, since Jane went to USC, she must be a great businesswoman. • TRW is a high paying company so Lester will make a lot now that he works for them.

9. Vagueness • Abuse of vagueness: Using a vague expression for it’s persuasive power as a substitute for evidence. • Homosexual behavior is perverse because it isn’t natural. • Puffery: Intentional overstatement in advertising. • Great Western Bank, we’ll always be there. • Gillette, the best a man can get. • Hype: Exaggeration: Amazing bargains! Incredible deals! Biggest sale of the season!

10. More Advertising Fallacies • Unspecified Comparison: • When a product is compared to an unnamed competitor. • Taster’s Choice Coffee- smoother taste. Smoother than what? • Less filling, lower in fat, etc. • Weasel Words: Advertisers use weasel words to make vacuous claims look substantive. • Make your floor look like new. • Helps you look younger! • Lasts up to eight hours.

11. Euphemism • Using a term that sounds nicer than the reality it refers to. • Passed on • Freedom fighters • Friendly fire • Terminate with prejudice • We have to separate you. • Loaded language- when the terms distort the issue. • Gun control fiasco • War on drugs • Abortion holocaust • Illegal alien invasion

12. Extreme Quantifiers and Intensifiers shut off debate. • Everything she says is a lie! • PETA activists are completely misguided. • Obamacare is totally flawed. • I know that my redeemer liveth! Your resume claims you are absolutely the greatest Economics instructor in the World (?)

13. Rhetorical Questions • A question with only one possible answer. • Do you want some government bureaucrat deciding whether or not you’re entitled to an operation? • Should scientists tinker in God’s work? • Phantom Distinctions: Making a distinction to suggest differences that don’t really exist. • No, you aren’t being fired but your position has been eliminated due to downsizing. • I’m not pro-abortion, I’m pro-choice.

14. Red Herring • When the arguer changes the subject to a different issue which is psychologically, but not logically, connected to the original issue. • Some people say we need to do more about airline safety. But more people are killed driving to the airport than in plane crashes. • How can you whine about dead seals when people are being killed in Africa?

15. Straw Person • Distorting another’s position (by making it appear more radical, extreme, or simplistic than it really is) and then attacking the distorted version of their view. • PETA members think a human life is no more valuable than the life of a cow, a rat, or even a cockroach. • Liberal’s think poverty causes crime. What happened to character and personal responsibility? • Professor Dylan favors legalizing marijuana. Apparently he wants to live in a society where everyone sits around stoned out of their minds all day long.

16. Two Wrongs • Shifts the blame by introducing an irrelevant comparison: • Henry Hyde argued that Clinton should be impeached. But he had an adulterous affair that destroyed a marriage. • Common practice: Justifying some morally suspect behavior by claiming that others do it too. • There’s nothing wrong with exaggerating your business expenses for the IRS. Everyone does it!

17. Ad Hominem • Ad hominem (against the person) attacks the arguer rather than the substance of her argument. • Abusive ad hominem: Attempts to discredit an argument by assaulting the character of the arguer. • Reverend Bud Green argues that hemp should be legalized. But he is a long-haired weirdo from Venice Beach, so what would you expect? • Atheism starts in the heart and spreads to the head. Norman Geisler

18. Circumstantial Ad Hominem • Attempting to discredit an arguer’s position by claiming that his view is dictated by his circumstances. • Cindy argued against the single payer health care proposal. But she works for Blue Cross, so of course she is against it! • Email adhominems Dear Mari, You stink and so does your argument.

19. Guilt By Association • Discrediting people, views, or arguments based on someone’s relationships with others. • We can ignore Rikki’s anti-fur argument. She belongs to PETA and they are extremists. Dear Tom, No wonder your position stinks because you are a stinking male! Love, Mari

20. More Ad Hominems • Genetic Appeal: Evaluating an argument or policy strictly in terms of its origin. • Christmas trees are of the devil! They were first used by Roman pagans. • Government health care plans are bad because they originated in socialist countries. • Poisoning the Well: Attempting to create prejudice against a position before it has been heard. • Come on, Cardinal Mahony! How can a celibate male give an argument on birth control.

21. Provincialism and Tradition • Provincialism: Appealing to group loyalty rather than evidence to support a position. • Support the B-2 Bomber! It means jobs for California. • The Teachers Union advises a no vote on measure S. • Appeal to Tradition: Claiming that a view is likely to be true because it is affirmed by tradition. • Marriage has always been an institution involving a man and a woman. So we should not permit same sex marriages. • Of course you will take my last name. Wives always do!

22. Novelty and Positioning • Novelty: It is good because it is new or different. • Vote Hayden, vote for change! • Positioning: Positioning a product or person with a better known rival. • 7-Up, the uncola. Damn, the novelty is already wearing off.

23. Emotional Appeals • Appeal to Anger: Arouse feelings of anger as a substitute for evidence. • If you want my gun you’ll have to pry it from my cold, dead, hand! • Appeal to Fear (or force) • Listen, Galileo, drop this heliocentric nonsense or Brother Vito will rotate your head around the sun! • Hurry in! These unbelievably low prices won’t last!

24. FEAR!

25. Appeal to Pity • Please officer! If I lose my license I’ll lose my job. Who will pay for Mama’s surgery? • Stop animal testing! Save Fluffy! • Keep animal testing! Save Granny! If not either p nor q imply not both r and s, then q is not quite true, I think. Please, no truth tables on the exam. I have an ulcer, I need less stress.

26. Appeals to Authority • Appealing to an authority who is either unqualified, biased, mistaken, or lying; or when there is no consensus of expert authority • Invincible authority: Using an authority to override all other evidence. • The Bible says, “wives, obey your husbands.” So start packing, we’re moving to Barstow. • Forget what your mama taught you, Susan. Charlie says we have to kill the pigs!

27. False Authority Unidentified Authority Irrelevant Authority • When expert opinion is alluded to without explicit identification of who the expert is. • Studies show that gun control doesn’t work. • Experts agree that legalizing pot would be a disaster. • The authority cited must be qualified on the topic in question. • Reverend John McArthur claims that the theory of evolution is not grounded in good science. Apologist Hank Hanegraaff, the Bible Answer Man, concurs with this opinion. Hence, we can conclude that evolution is a flawed theory.

28. More False Authority Fallacies • Testimonials: When a celebrity or unknown user of a product endorses it’s value, their testimony provides weak support. • Tiger Woods says drive a Buick, chicks dig it! • I lost 50 lbs in two days with the lap band! • Division of Expert Opinion: When the experts have not reached a consensus, we cannot appeal to one expert’s view to resolve a dispute. • We know alien abductions really occur. Even Harvard psychiatrist John Mack believes alien abduction reports are authentic.

29. Conflict of Interest • Bbb • Trust me, I know! • When there is reason to believe that the authority cited has a vested interest in the topic, his or her testimony is compromised by bias. • The CEO of Shell Oil says offshore drilling is completely safe, so we can approve their request to drill.

30. Statistical Inference Fallacies • Small Sample: Overestimating the statistical significance of evidence derived from too few cases. • In a published article, three gay men testified that their homosexuality was a choice, not a decision forced on them by their genes or upbringing. Thus, there is no biological basis for male homosexuality. • All three of my husbands had affairs so don’t deny the fact that all men are cheaters. • My husband died of brain cancer and he was a pot smoker so marijuana smoking causes brain cancer.

31. Unrepresentative Sample • Overestimating the statistical significance of a sample drawn from a particular sample group where a bias influences responses. • Of 50,000 residents of Salt Lake City surveyed, 90% say they oppose legal abortion. This shows that Americans overwhelmingly oppose abortion. • Biased Methodology: A study that uses loaded or leading questions, restricts range of responses, etc. • Do you favor Obama’s socialistic health care reform that will bankrupt our country, or do you prefer to continue to allow private enterprise to deliver the best health care in the world?

32. Suppressed Evidence • Deliberately ignoring evidence that tends to undermine one’s position. • I was the number one salesman in the firm. • See how much dirt was left behind by your vacuum when we vacuum the same area with the Oreck 3000! • We have less ships than we had in 1916. • Bad Base Line: Overestimating the significance of some trend (in crime rates, welfare rates, unemployment rates, etc.) • Gambler’s fallacy: Thinking past results of chance events affect the probability of future results. • I’m due to win, baby!

33. Faulty Analogy • An argument from analogy is weak when it ignores relevant dissimilarities between the items compared or uses similarities that are not relevant to the conclusion. • Sure guns kill, but so do baseball bats and no one wants to ban them! • Guns kill people like spoons made Rosie O’Donnell fat and pencils misspell words and cars make people drive drunk. • "This bill [to ban the carcinogen chlordane] reminds me of legislation that ought to be introduced to outlaw automobiles" on the grounds that cars kill people, said Rep. Tom DeLay, R-Texas,

34. Ad Ignorantiam • An argument from ignorance misplaces the burden of proof by claiming either that because a certain claim has not been proven false, it is probably true, or that because a claim has not been proven true, it is probably false. • No one can prove that angels don’t walk among us! • Invincible Ignorance: To refuse to accept the burden of proof by denying all evidence that contradicts a position. • You can keep your fossils and biology books, Genesis is God’s word and it don’t say I come from no monkey!

35. Causal Fallacies • Confusing correlation with causation. • 83% of criminals drink alcohol before committing crimes. So Alcohol use causes crime. • Post hoc ergo propter hoc. Mistaking temporal succession for causal connection. • Prayer works! I said four “Hail Mary’s” before the game and the Chargers won! • Common Cause: Inferring a causal connection when two items are both produced by an underlying cause. • 75% of Prozac users have contemplated suicide. That stuff is dangerous!

36. Causal Oversimplification • Mistaking a contributing cause as the primary cause. • We can resolve the budget crisis in California if we crack down on illegal immigration and stop giving benefits to people who are here illegally! • False Inference to Best Explanation: Maintaining an implausible hypothesis simply because you haven’t thought of a better explanation. • I must have been a Egyptian princess in a past life because I uttered some Egyptian words during hypnotherapy.

37. Questionable causal assumptions • Disease and natural disasters are divine punishments for human sin. • Comic books, or video games, or certain types of music produce juvenile delinquency • A close brush with death means God saved you from harm. • Demons are influencing events. • Personality is affected by date of birth. • George Bush was responsible for 9/11 • Genetically modified food is harmful. • God wants one person to kill another.

38. Slippery Slope • An unwarranted prediction of disastrous results from adopting some policy. • If we allow terminally ill patients to take their own lives, respect for the sanctity of life will diminish. Soon the elderly and the disabled will be killed against their will.