Logical Fallacies

ERRORS IN THOUGHT have pestered humanity long enough to be categorized, hopefully for the purposes of avoiding such mistakes in the future. Although some errors are blatant enough to be recognized immediately (usually delineated by startled gasps of outrage from the audience), others are subtle and devious enough to even fool the perpetrator himself.

These fallacies are based on material from A Concise Introduction to Logic, 3rd Edition by Patrick J. Hurley, 1988.

Fallacies of Relevance (conclusions supported by emotion, instead of logical premise)

1. Appeal to Force (Argumentum ad Baculum, or "The Big Stick"): The arguer threatens the listener's psychological or physical well-being in order to win his point.

• "Give me what I want, or say hello to Charlie here. Charlie's my shotgun."
• "Of course I deserve a raise: It would be a shame if your husband found out about Fabio, after all this time..."

2. Appeal to Pity (Argumentum ad Misericordiam): The arguer offers a solution and then tries to sway his listener with a tale of woe.

• "But MOM, if I don't attend Jill's eyelash-piercing party, I'll never be able to show my face at school again!"
• "Without that new MMX Pentium II computer and 21" monitor, I might as well be shot now."

3. Appeal to the People (Argumentum ad Populum): The arguer tries to either excite the audience's enthusiasm or appeals to someone's vanity, snobbishness, or makes a bandwagon argument.

• "All POPULAR people style their hair with the Fluffalizer. Are you fluffalacious, or do you prefer being drab and stringy?"
• "Our new food coupon business deal isn't for anyone -- just for the most brilliant!~ Just the fact you're here shows how smart you are, so I think you should shell out the $800."

4. Argument against the Person (Argumentum ad Hominem): The arguer tries to discredit the actual argument by either putting down his opponent or claiming that his opponent has ulterior motives for his argument.

• "Yes, it's true that Vergil Smithers supports that anti-turtle amendment. Of course, he also picks his nose, wears socks that don't match, and tapes Melrose Place to watch when he thinks no one else is around, so who wants to believe HIM?"
• "Of course Bill Gates would say that Microsoft hasn't broken the anti-trust laws. He'd have to dip into his piggy bank if he admitted to it."

5. Accident: The arguer wrongly applies a general rule to a specific case.

• "People REALLY shouldn't lie to each other. It's SO uncivilized. So I will ask you one more time, Mr. Hess: Are there any Jews hiding in your basement?"

6. Straw Man: The arguer distorts his opponent's argument so as to more easily attack it, and then claim that the original argument was defeated.

• "Alright. Crisco Green has asked permission to drink soda at his work desk. However, dragging food into the office is a really crummy idea. After all, what's coming next? Breakfast runs? Pizza delivery? Lunch buffets? Catered dinners? Oh, the rats will love THAT. And soon the bums will be going through our dumpsters looking for scraps! We can't work with all that noise and distraction! Our business will be the butt of every joke! Green's request is utterly absurd."

7. Missing the Point (Ignoratio Elenchi): The arguer's premises seem to lead in one direction but then reach a completely different conclusion.

• "Based on the recent cases of termite infection in the local area, we really have no choice but to burn down the entire town. After all, it's the only way to be sure."
• "Those professional jocks are always getting themselves into trouble. To cut violence in prison, our course is clear: Don't let inmates watch ESPN on TV."

8. Red Herring: The arguer diverts attention by switching topics, then draws an irrelevant conclusion or presumes that a conclusion been established and that he has thus won the argument.

• "Alright, so everyone's whining about the lack of Slurpee flavors at 7-11. But the fluctuating milk prices have been making life difficult for the owner, and despite the recent declining cow population, he's managed to carry chocolate, strawberry, and 2% milk all on his own initiative, paying the margin out of his own pocket! He's giving calcium to growing kids, you know. No matter what you say, I think he's a real swell guy!"

Fallacies of Weak Induction (the conclusion is not adequately supported)

9. Appeal to Authority (Argumentum ad Verecundiam): The arguer appeals to an authority who is unqualified, or probably mistaken, biased, or lying.

• "Well, Dr. Swensen said the appendix needed to come out immediately. It's not his fault he teaches economics."
• "Of course she's telling the truth about Jamaar's innocence. She carried his child, you know."

10. Appeal to Ignorance (Argumentum ad Ignorantiam): The arguer draws a definite conclusion in a case where nothing has been proven one way or the other.

• "It's never been proven that Oswald was alone, so the assassination MUST have been a conspiracy."
• "Well, if I probably didn't learn snorin' from my folks, I musta been born with it."

11. Hasty Generalization: The arguer uses a sample that is not representative of the group.

• "My blind date belched the whole way through dinner, and this morning the ugly slob next door walked down the hall wearing nothing but ratty old boxers. I'm telling you, Phil, all women are pigs."

12. False Cause: The arguer makes a link between his premises and his conclusion that depends on some imagined connection that probably doesn't exist.

• "The corner office -- every good exec has one. If Seymour's gonna measure up, we'll have to move Jenkins into the broom closet."
• "No, Mother, the RED earrings! RED! I'll flunk cheerleader tryouts if I wear BLUE!"

13. Slippery Slope: The arguer bases his conclusion on some supposed link of chain reactions that will most likely not ever occur.

• "Buffy the Vampire Slayer should be taken off the air, or people will get too scared to go out at night. In fact, people will purchase protection devices -- mace, pistols, tasers, and really big spiked baseball bats, the whole works! With all those paranoid nuts running around, the streets won't be safe for anyone, and they'll all stay indoors at night! And in winter, with the shorter days, businesses will lose sales. Eventually the economy will collapse, America will go broke, and THEN where are we gonna be?"

14. Weak Analogy: The analogy used by the arguer to support his conclusion is not strong enough to effectively do so.

• "Dinosaurs are a bunch of animals that went extinct. Since hedgehogs are animals too, they're probably next on the list."

Fallacies of Presumption, Ambiguity, and Grammatical Analogy (the answer is presumed or ambiguous, or the premises are misunderstood)

15. Begging the Question (Petitio Principii): The arguer uses some sort of phrasing that conceals the questionably true character of a key premise.

• "Of course miracles don't happen. They're events that contradict natural law, and we already know that nothing can contradict natural law."
• "But the Pope's NEVER wrong! After all, he's infallible!"

16. Complex Question: The arguer asks a single question that is really two questions combined, forcing the single answer to apply to both questions.

• "Stopped that embezzlement racket yet, Joe?"
• "Alright. Did you put back the cookies you stole from my safe?"

17. False Dichotomy: The arguer presents an either/or alternative, when in fact more options exist.

• "If you don't let me go to the mall with my friends tonight, I'll be forced to run off with an Elvis impersonator. Can you live with that?"
• "Your car can look like acne, or you can wax it with MiracleShine and make your friends drool!"

18. Suppressed Evidence: The arguer ignores evidence that would probably undermine the point of his otherwise good argument.

• "Our knives are so great, if they break while under warranty, we'll replace them FREE! OF! CHARGE!" [Note: Warranty covers shipping time only.]
• "Yeah, so I blew up the guy's house. But don't the Constitution say I got a right to liberty?"

19. Equivocation: The arguer draws a conclusion based on words that are used in different senses in the same argument.

• "According to the Bible, 'Their rock is not as our Rock!' Ha ha ha! Rock music IS from the devil!"

20. Amphiboly: The arguer misinterprets an ambiguous statement, leading to a faulty conclusion.

• "He said our business was going downhill, so I ran outside to see if I could stop the building from sliding any further."

21. Composition: The arguer bases his conclusion on a faulty transference of a characteristic from parts onto a whole.

• "Well, wood particles are brittle enough to break with my bare hands, so I figure I can break this particle board with my bare hand, no sweat. Drum roll, please!"

22. Division: The arguer bases his conclusion on a faulty transference of a characteristic from the whole unto its parts.

• "John just LOVES cookies. Cookies are made of flour, and I've got bags of the stuff. Do you think he wants one bag or two for dinner?"

Hosted by www.Geocities.ws