Glossary of Logical Fallacies (Unsound Arguments)

Transcription

1 Glossary of Logical Fallacies (Unsound Arguments) Glossary of Logical Fallacies 1 Logical fallacies are errors in reasoning that undermine the validity of an argument. You need to be aware of these types of arguments so that you can avoid using them and so that you aren t easily persuaded by them. We ll work on crafting qualified, defendable arguments next. I. Appeal to Patriotism (jingoism) Attempting to persuade by calling on someone s love of their country. USA! USA! Example 1. Support our troops! 2. The United States is the best country in the world! The old way is always better! II. Appeal to Tradition (argumentum ad antiquitatem) Arguing that something is right because it is the accustomed or traditional thing to do. 1. X is old or traditional 2. Therefore X is correct or better. Example Marriage has always been between a man and a woman! That can t change! III. Argumentum Ad Hominem Attacking or insulting a person s character instead of their ideas, evidence, arguments, or beliefs. You re stupid! 1. Person A makes claim X. 2. Person B makes an attack on person A. 3. Therefore A's claim is false. Example: Person A: I don t think we should go to the movies. We need to save money. Person B: Why do you have to be so boring? IV. Argumentum Ad Nauseum Repeating a premise or slogan over and over again in the hopes an audience will believe it simply because you said it so many times. It must be true cuz 1. A = A... A = A... A = A... A = A... A = A... A = A... s/he said it a lot Example: Saying someone is a liar over and over again until people believe it to be true, even though you lack clear evidence: He s such a liar... he never tells the truth... you can t trust him... he s always lying... you believed someone who lies?...

2 Glossary of Logical Fallacies 2 Lemmings V. Bandwagon (argumentum ad numerum or ad populum) Pointing out that most people are now doing something, especially something new (ad novitatem), to convince them to do or belief something. 1. Person A observes that X is popular or cool 2. Person A does X Example: Why do you listen to that old people music? Metallica rules! You should listen to Metallica! All my friends are metal-heads now! Trust me, I m famous! VI. Appeal to authority/character (argumentum ad verecundiam) Using the celebrity or fame of others to convince an audience of something. 1. Person A claims to be an authority on subject S. 2. Person A makes claim C about subject S. 3. Therefore, C is true. Example A: Michael Phelps isn t an expert on nutrition, he s an expert at swimming, nor did his training regimen rely on or primarily consist of, Subway sandwiches, but he s endorsing them, which suggests they re related to his success. Example B: I'm not a doctor, but I play one on TV, and when I get a headache, I use Aspirin. VII. Begging the Question (Petitio Principii) When a speaker derives a conclusion from a question that presupposes the conclusion. 1. A is true because A is true or A is true because B is true, and B is true because A is true Example: 1. Isn t my dog the greatest? It s because she s the best. 2. What would you do without freedom? Without it you wouldn t be free! 3. If we don t have rules, this place will be lawless! VIII. Circular reasoning Using a proposition as both a premise and a conclusion. I m right because I m right! 1. A is related to B 2. Therefore B is related to A Example A: I have the greatest dog in the world because she is the best dog ever! Example B: Example: Seattle is full of hippies without jobs so none of them are employed.

3 Glossary of Logical Fallacies 3 VIX. Bifurcation / False Dilemma Trying to suggesting there are only two options in a situation. There are only two options! 1. Either claim X is true or claim Y is true. 2. Claim Y is false. 3. Therefore claim X is true. You re either with us, or against us! Example A: You need to graduate to go to college, and most prison inmates didn t graduate, so do you want to go to prison or college next year? Example B: You can t be both Christian and a Scientist! X. Sweeping generalization (dicto simpliciter ) When you apply a general rule too broadly. 1. A = B 2. Therefore all A s = B Example: I don t want a job. I want to stay at home and raise my kids. That s what all women want to do! XI. Hasty generalization When you use a general conclusion on the basis of just a few examples. 1. One or two A's are B's. 2. Therefore all A's are B s. They re all the same! Example: I was nearly hit by an old lady in a van on the way to work. We really need to get old people off the road. They re dangerous! XII. Equivocation/ambiguity (Doublespeak/puns) Using different meanings of one word to trick an audience. Pun; Example 1: My opponent may be a right wing conservative, but he hasn t said Wordplay; anything right about our economy! Two Example 2: Our president said he had confidence in the American people, but he meanings can t keep a secret! So can we really tell him anything in confidence? Can we trust him? XIII. False analogy Using a comparison that is very weak, inappropriate, or based on a misunderstanding. 1. P and Q are similar in respect to properties A,B, and C. 2. Object P has been observed to have further property X. 3. Therefore, Q probably has property X also. A is to B as Z is to D Example 1: Kids are just like dogs. You can t get them to work unless you give them a treat. Example 2: Students are like nails. Just as nails must be hit in the head in order to make them work, so must students.

4 XIV. Appeal to emotion manipulating an audience s emotions rather than appeal to reason or logic, to get them to believe an argument. 1. Y is presented (a claim that is intended to play to one s emotions) 2. Therefore claim X is true (a claim that is generally, but need not be, related to Y in some manner). Example a World War two poster that shows a dog sulking on his dead masters Navy uniform because someone leaked information. XV. Appeal to Fear/Power Scaring people into doing as you ask or frightening them into believing an argument. Glossary of Logical Fallacies 4 I m scared! 1. Y is presented (a claim that is intended to produce fear). 2. Therefore claim X is true (a claim that is generally, but need not be, related to Y in some manner). Example: I m going to flunk you if you don t do your homework. Understand? XVI. Post hoc ergo propter hoc (after this, therefore because of this) When it is assumed that because one event happened before another, the first event caused the second 1. A occurred, then B occurred. 2. Therefore, A caused B. Example Someone was lighting off fireworks and then a car wrecked in the intersection by my house. They must ve been distracted by the noise and ran the light. XVII. Cum hoc ergo propter hoc (with this, therefore because of this) When it is assumed that because two things happened simultaneously, one must ve cause the other 1. A and B occurred at the same time 2. Therefore either A cause B or B caused A Both A and B happened at once so A caused B or B caused A Example: I heard a story that my grandpa died in an airplane crash in the 40 s so he must have died in combat. XVIII. Non sequitur (it does not follow / does not make sense) an argument in which your claim and conclusion are bizarrely unrelated, often for humorous effect. 1. A + B = Yes 2. Therefore, goldfish What the what? Example People who don t wear a seatbelts are twice as likely to die as those who do, so if you don t wear a seatbelt your car will explode.

5 XIX. Loaded Question/trick question (plurium interrogationum) A trick question that contains an unjustified assumption. Example: Do these pants make me look fat? or When did you stop caring about your kids? or How long have you sucked at baseball for? XX. Red herring (derailing) Using an irrelevant claim to distract someone from a relevant argument; herring are stinky and can throw a hound off track. Glossary of Logical Fallacies 5 1. Topic A is under discussion. 2. Topic B is introduced under the guise of being relevant to topic A (when topic B is actually not relevant to topic A). 3. Topic A is abandoned. Look! An elephant! Example 1: I know that most of you want to vote for Billy, but global warming is a serious issue and we need to address it or the Earth is doomed. Example 2: Classes should be harder for students to pass. We have to press for that because we re in a budget crisis and could lose our jobs. XXI. Slippery slope argument An argument that states a small step in a certain direction will result in a chain of uncontrollable events that will lead to a terrible ultimate outcome. 1. Event X has occurred (or will or might occur). 2. Therefore event Y will inevitably happen. If you do that we re all going to die! Example: College is too expensive. If we don t do something to stop it tuition will be 100,000 dollars a year! XXII. Straw man Misrepresenting another s opinion to make it easier to pick apart. 1. Person A has position X. 2. Person B distorts position X into position Y, which is easier to tear apart. 3. Person B attacks position Y. 4. Therefore X is false/incorrect/flawed. You re putting words in my mouth! Example: Person A: I didn t pass my math class. I wish I had of tried harder. Person B: Yeah, well there s nothing you could do about it now. Like you said, you didn t pass it because you were lazy and didn t study. Now you ll have to take it again next year.

6 Glossary of Logical Fallacies 6 XXIII. Syllogism A formal deductive argument made up of a major premise, a minor premise, and a conclusion. This follows the formula: Major Premise: A (Bill wears glasses) Minor Premise: B (Bill is a man) Conclusion: Therefore all B s are A s (All men wear glasses)