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Logical Fallacies

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  1. Logical Fallacies These are bad.

  2. What is a logical fallacy? • That term refers to “faulty logic.” • Generally speaking, logical fallacies are errors in reasoning. • These errors undermine the strength of the argument and hurt the credibility of the author/speaker.

  3. Why are we concerned about logical fallacies? • The ability to identify logical fallacies in the arguments of others, and to avoid them in one’s own arguments, is a valuable skill. • Fallacious reasoning hides the truth. • When we can’t identify fallacies, we’re vulnerable to manipulation by those skilled in the art of persuasion.

  4. Ad hominem • In this fallacy, a personal attack is made against an opponent’s character instead of against an argument (sometimes called “name-calling”). • Examples: Greenpeace doesn’t do any good because its members are a bunch of hippies. People who disagree with affirmative action are racists. You’re so stupid that your point couldn’t possibly be valid.

  5. Ad ignorantium • This argument assumes that if something can’t be proven true, it must be false—and vice versa. • Examples: God doesn’t exist; you can’t prove he does. God does exist; you can’t prove he doesn’t. • I don’t think this argument is going anywhere, do you?

  6. Ad populum • This emotional appeal speaks to positive (such as patriotism, religion, democracy) or negative (such as terrorism or socialism) concepts rather than the real issue at hand. • Example: If you were a true American, you’d support the 2nd Amendment. • Nobody wants to be called unpatriotic!

  7. Appeal to force • This argument says that something bad will happen if the audience doesn’t agree. • Example: If you don’t believe in God, you’re going to hell. • Appeal to force includes threats and is designed to scare the audience.

  8. Argument from personal incredulity • This argument goes like this: “I cannot explain or understand this; therefore, it cannot be true.” • Example: I cannot imagine how natural forces could create the complexity of nature; evolution just can’t be possible! • Pointing out your own ignorance is not a good persuasive technique.

  9. Bandwagon fallacy • Something is assumed to be valid because of popular support. • Examples: Does God exist? Billions of people can’t be wrong! But Mom! Everybody has that kind of phone! • Nobody wants to be left out!

  10. Circular reasoning • This claim uses its own conclusion as evidence; it says the same thing twice, ending up where it started. • Examples: God exists. I know that because the Bible says so, and the Bible is the inspired word of God. Martin Luther King Jr. was a great speaker because he was so eloquent. • We’re going in circles!

  11. Complex cause • A complex event is shown as having only one cause. • Example: We lost the game because Gertrude missed the last shot. • This argument is as logical as putting the blame on the first missed shot of the game.

  12. Either/or fallacy (false dilemma) • Only two options are given when many choices exist. • Examples: Either you’re for the Republican plan or you’re a socialist. We can stop using fossil fuels, or we can destroy the earth. • Few issues are this black and white.

  13. Equivocation • This fallacy uses a word with two different meanings. • Examples: The sign said, “Fine for Parking Here,” so since it was fine, I parked here. God helps those who help themselves, so I’m going to help myself to more tater tot hot dish. • People who equivocate often think they’re very clever. They’re not.

  14. False analogy • This fallacy compares two things that are not similar enough to compare. • Example: That political candidate is the Jesus Christ of the 21st century. • Really?

  15. Faulty cause and effect • This argument attempts to make a connection between two consecutive events. • Example: Shortly after that phone call, I saw Gertrude crying. She must have gotten some bad news. • We can’t make that claim without more information.

  16. Genetic fallacy • This argument brings up irrelevant history or origin. • Example: Hitler’s regime developed the Volkswagen Beetle, so you shouldn’t buy one. • Hitler isn’t making any money on VW sales, is he? What is the philosophy of that company now?

  17. Hasty generalization • This claim draws a conclusion based on insufficient evidence. • Examples: Women are bad drivers. All frat boys love to party. Even though this is only the first day, I can tell this class is going to be boring. • Many hasty generalizations are based on stereotypes.

  18. Moral equivalence • Something minor is compared to something serious, as if they are equal. • Example: The police officer who gave me a ticket is a Nazi. • While you might be trying to use hyperbole for effect, be careful about doing so using terms like “Nazi.”

  19. Prejudicial language • Loaded words and terms are used. • Examples: Right-wing fanatics and NRA stormtroopers will fight to keep their guns. Bleeding-heart liberals are going to drive this country into bankruptcy. • Do you think the “right-wing fanatics” and “bleeding-heart liberals” are willing to continue this discussion?

  20. Red herring • This diversionary tactic detracts from or avoids the issue at hand. • Examples: The levels of mercury in seafood might beunsafe, but what else are fishers supposed to do for a living? Question: Did the president have an affair? Answer: The president is busy with Middle East peace talks and has no time for silly accusations. • Do you know what a herring is?

  21. Slippery slope • This argument follows a claim to an unsupported conclusion. • Example: If you skip class once, you’ll do it again…and again…and again—and before you know it, you’ll have dropped out of school and be living in a van down by the river.

  22. Straw man • This move misrepresents or oversimplifies an opponent’s viewpoint and then attacks it. • Example: Proponents of sex education want to give kids license to have sex with no consequences. • Do you really think that’s what they want?

  23. Two wrongs • This argument attempts to use one wrong to justify another. • Examples: So what if I cheated on my taxes? Lots of people do. You say I shouldn’t speed, but you do. • Two wrongs don’t make a right!