Presentation Transcript

1. Logical Fallacies

   “I know you are, but what am I?”
2. Why don’t these arguments work? Television can’t be harmful to children because it occupies their attention for hours and thus keeps them off the streets Marijuana can’t be all that bad. Everyone knows about barroom brawls, but marijuana makes people peaceful Shakespeare cannot have been a great writer, for he did not even make up his own plots Doctors are all alike. They really don’t know any more than you or I do. This is the third case of faulty diagnosis I’ve heard of in the last month We ought to be guided by the decision of our ancestors, for old age is wiser than youth
3. Why don’t these arguments work? The end of a thing is its perfection; death is the end of life; death is, therefore, the perfection of life You can tell that Frank is a disreputable person by the character of his associates, because people who go around with somebody like Frank are the lowest type Comedian W.C. Fields said he knew a sure cure for insomnia –a good rest I’m surprised at you. A person of your culture and upbringing –defending those hoodlums!
4. What is a logical fallacy? Usually incorrect argumentation in reasoning resulting in a misconception or presumption. Reasoning must be potentially deceptive, it must be likely to fool at least some of the people some of the time. In order for a fallacy to be worth identifying and naming, it must be a common type of logical error. A fallacy isn’t a false conclusion but a weak one.
5. Why Study Fallacies? Why study how to reason incorrectly; why not just study how to reason correctly? Even if you are right100% of the time, others may not be. It’s like having a road map that shows how to get from point A to point B.
6. Common Fallacies: Ad hominem “Against the man, against the person” Attacks the person’s character, habits, morals, or personality Example: “Teenagers don’t know anything about true love. How could they; they are so young and inexperienced!”
7. Common Fallacies: The Appeals Appeal to: Authority: “I'm not a doctor, but I play one on Grey’s Anatomy. I choose Advil for all my headaches.” Emotion: “The new UltraSkinny diet will make you feel great. Enjoy the admiring stares of the opposite sex. You will know true happiness if you try our diet!” Fear: “I really need to get an A in this class. My father, the principal, would really appreciate that.” Pity: “I'm positive that my work will meet your requirements. I really need the job since my grandmother is sick.” Tradition: “Of course this mode of government is the best. We have had this government for over 200 years and no one has talked about changing it in all that time. So, it has got to be good.”
8. Common Fallacies: Bandwagon a threat of rejection by one's peers (or peer pressure) is substituted for evidence in an "argument.” Idea X is popular. Therefore, X is correct Example: “Most people believe Michael Jackson is the greatest entertainer of our time. Therefore, Michael Jackson is the greatest entertainer of our time.”
9. Common Fallacies: Begging the question the premises include the claim that the conclusion is true or (directly or indirectly) assume that the conclusion is true similar to: circular argument Example: "If such actions were not illegal, then they would not be prohibited by the law.” “Have you stopped cheating in school?”
10. Common Fallacies: Dicto Simpliciter acceptable exception is ignored or eliminated a general rule is treated as universally true regardless of the circumstances Example: "Birds normally can fly. Tweety the Penguin is a bird. Therefore, Tweety can fly."
11. Common Fallacies: Equivocation a word is incorrectly (on purpose) used to make an argument doublespeak Example: A feather is light. What is light cannot be dark. Therefore, a feather cannot be dark.
12. Common Fallacies: False Dilemma only two alternatives are considered, when in fact there are additional options; oversimplification Black and white thinking Example: Either you're for me or against me.
13. Common Fallacies: Hasty Generalization conclusions made about a population based upon a sample which is too small to be representative often committed because of bias or prejudice Example: Smith is from England. While on a trip to the US to visit Penn State, he sees two white squirrels. Back in England he tells his family that all American squirrels are white.
14. Common Fallacies: Non sequitur conclusion does not follow from its premises disconnection between the premise and the conclusion Example: Life is life and fun is fun, but it's all so quiet when the goldfish die.
15. Common Fallacies: Poisoning the Well involves trying to discredit what a person might later claim by presenting unfavorable information (be it true or false) about the person Example: “Don't listen to him, he's a liar.”
16. Common Fallacies: Post Hoc, Ergo Propter Hoc after this, therefore because of this Example: “Every time I take a vitamin I get sick. Vitamins make me sick.”
17. Common Fallacies: Red Herring any argument in which the premises are logically unrelated to the conclusion commits this fallacy. an irrelevant topic is presented in order to divert attention from the original issue Example: “I know I forgot to deposit the check into the bank yesterday.  But, nothing I do pleases you.”
18. Common Fallacies: Slippery Slope undesirable outcome is the guaranteed result of a chain of actions. Therefore, the first step should never be taken. a person asserts that some event must inevitably follow from another without any argument for the inevitability of the event in question. Example: “You can never give anyone a break. If you do, they'll walk all over you.”
19. Common Fallacies: Straw Man a person simply ignores a person's actual position and substitutes a distorted, exaggerated or misrepresented version of that position Example: “Senator Jones says that we should not fund the attack submarine program. I disagree entirely. I can't understand why he wants to leave us defenseless like that.” Person A: Our society should be taxed less. Person B: It is unjust to promote a society that neglects the poor.
20. Common Fallacies: TuQuoque “you too” Fallacy committed when it is concluded that a person's claim is false because: it is inconsistent with something else a person has said, or what a person says is inconsistent with her actions. Example: Peter: “Based on the arguments I have presented, it is evident that it is morally wrong to use animals for food or clothing.” Bill: “But you are wearing a leather jacket and you have a roast beef sandwich in your hand! How can you say that using animals for food and clothing is wrong!” or “I know you are but what am I?”
21. Common Fallacies: Two Wrongs Make a Right a person "justifies" an action against a person by asserting that the person would do the same thing to him/her attempt to justify a wrong action by pointing to another wrong action Example: After leaving a store, Jill notices that she has underpaid by $10. She decides not to return the money to the store because if she had overpaid, they would not have returned the money.
22. Spot the fallacy! http://www.thedailyshow.com/watch/thu-june-28-2007/immigrant-disease
23. She’s a witch!
24. Homework Look through newspaper articles (online or paper), print advertisements, or anything you find that is relevant, and find 5 logical fallacies. In 1 paragraph per fallacy, state: The source The audience The message/how is it trying to persuade the audience The fallacy Explanation/examination of fallacy Attach the article to your paper and hand-in Tuesday, November 15th. Thank you!