INFORMAL FALLACIES. Engel, S. Morris With Good Reason: An introduction to Informal Fallacies. 6 th ed. Bedford.

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1 INFORMAL FALLACIES Engel, S. Morris With Good Reason: An introduction to Informal Fallacies. 6 th ed. Bedford

2 *Fallacy of Presumption: "Justice requires higher wages because it is right that people should earn more." This amounts to: "justice requires higher wages because justice requires higher wages. God exists! How do you know? The Bible says so. How do you know that what the Bible says is true? Because the Bible is the word of God! --Begging the question: (petitio principii) The argument uses the conclusion that it seeks to establish. It assumes the conclusion in its premises.

3 *Fallacies of presumption: "Since I'm not lying, it follows that I'm telling the truth. Bill: I enjoy only good books. Tom: How do you know when they re good? Bill: If they re not good, I don t enjoy them. -- Circular definition: The definition includes the term being defined as a part of the definition; Using the concluding claim as evidence to support the conclusion.

4 *Fallacies of relevance: "If we lower the drinking age from 21 to 18, then what next? 16 year olds being allowed to drink? 14 year olds?" "If we allow the French to influence us, we'll soon be eating nothing but snails and garlic." --Slippery slope: Supposing that a single step in a particular direction must lead to the extreme position.

5 . Fallacies of presumption: "After Ketchup was considered a serving of vegetables in school meals, math scores dropped nation-wide. Therefore, ketchup causes math scores to drop." -- Post hoc ergo propter hoc: (Post hoc for short. Latin: "after this, therefore because of this.") Because one thing follows another, it is held to cause the other. FORM: Event C happened immediately prior to event E. Therefore, C caused E.

6 *Fallacies of presumption: "In K-12 children, neater handwriting causes larger feet. The number of cases of drowning increases as the sale of ice cream increases. So eating ice cream must cause drowning. -- Cum hoc ergo propter hoc: Assumes events which occur together are causally connected, and there is no room for coincidence or for other causal factors. FORM: Events C and E both happened at the same time. Therefore, C caused E.

7 *Fallacies of relevance: "If you are not with us, you are against us." -W --Bifurcation: Presenting only two alternatives where others exist; black and white thinking. ALSO: FALSE DILEMMA

8 *Fallacies of relevance: "How can you condone usury? You're a Christian, and Christ drove the money-lenders from the temple." As an opera-lover, you will be the first to agree that we need more subsidy for the arts." -- Argumentum ad Hominem: Attacking the arguer rather than the argument itself. It also includes invoking the proponents position. ALSO: TU QUOQUE

9 *Fallacies of relevance: "Since you based your theory of Bigfoot on stories from The National Enquirer, the theory must be false. The war on drugs started from strict Puritanical heritage. So we don t have to encourage drug control. -- The genetic fallacy: (p. 89) Attacking the source of the argument rather than the argument itself. It is a fallacy, because how an idea originated is irrelevant to its validity.

10 *Fallacies of relevance: "You can't tell me smoking is bad when you've been smoking for thirty years." -- Tu Quoque: ("you also") Undermining a case by claiming that its proponent is himself guilty of what he talks of.

11 Anecdotal evidence Anecdotes and stories These are events that happen to someone, or that are told to them, with no attempt at any scientific analysis. Some are simply stories, events that did not really happen or that have been significantly altered (for example urban legends). They are useful for adding interest, and in illustrating points, but they should not be used to make generalizations. "This is third day in a row that we've had a record high temperature. Global warming must be 12real."

12 *Fallacies of relevance: "The credit card company will take my late fee off. Otherwise I'll be so broke I can't pay them anything." --Wishful thinking: Rejecting a claim solely because we do not wish it to be true.

13 *Fallacies of relevance: We should liberalize the laws on marijuana. No. Any Society with unrestricted access to drugs loses its work ethic and goes only for immediate gratification. -- Straw Man: A deliberate over-statement of an opponent's position. Stating a position that no one holds.

14 *Fallacies of relevance: "It cleans your teeth white! Yes, that's right-- whiter than white!" -- Argumentum ad Nauseum: Repetition of a point, often by exaggerating or slightly changing the point.

15 *Fallacies of language: "Hitler summons war lords! "Scotland stole a goal in the first half, but England's efforts were rewarded..." --Loaded words: (also emotive argument) The deliberate use of prejudiced terms to conjure a more favorable or hostile response.

16 *LINGUISTIC FALLACIES "This must be a good orchestra because each member is a talented musician." Composition: Claiming that what is true for individual members of a class is also true for the class as a whole.

17 *LINGUISTIC FALLACIES "Germany is a militant country. Thus, each German is militant. "Because the brain is capable of consciousness, each neural cell in the brain must be capable of consciousness." Division: Attributing to the individuals in a group something that is only true of the group as a unit.

18 LINGUISTIC FALLACIES "All child-murderers are inhuman, thus, no child-murderer is human. "My dog's got no nose/ How does he smell?/ Terrible!" Equivocation: Using words ambiguously; equivocal words have more than one meaning.

19 LINGUISTIC FALLACIES You are not entitled to your opinion. Equivocation: Using words ambiguously; equivocal words have more than one meaning.

20 LINGUISTIC FALLACIES 1. If someone is entitled to an opinion then her opinion is well-supported by the evidence. (This is precisely what it means to be entitled to an opinion). 2. I am entitled to my opinion (as is everyone in a democratic society). 3. Therefore, my opinion is well supported by the evidence.

21 FORMAL FALLACIES Consider the true premise: If there is fire, oxygen is present. "Oxygen is present, therefore there is fire. "If I drop an egg, it breaks. This egg is broken, so I must have dropped it." --Affirming the consequent: (Remember: biconditional) Believing that the consequent (the second phrase) necessarily entails the antecedent.

22 FORMAL FALLACIES Consider the premise: If there is fire, oxygen is present. There is no fire, therefore there is no oxygen. Consider the premise: If I am hungry in the morning, I will eat breakfast. I am not hungry in the morning, therefore I will not eat breakfast. --Denying the antecedent: Believing that when the antecedent is false, the consequent must be false also.

23 *INDUCTIVE FALLACIES: The apples on the top of the box look good. The entire box of apples must be good. --Unrepresentative sample: The sample used relevantly different from the population as a whole.

24 *INDUCTIVE FALLACIES: "I'm backing Hillary Clinton on this one. She can't be wrong all the time. I m betting red on the Roulette table. The last five times was black, so it s bound to be red soon. --Gambler's Fallacy: Believing the next outcome will somehow be influenced by the last outcome. This only applies to cases of independent trials, like rolling the dice.

25 *Fallacies of relevance: "We don't know what caused the door to slam, therefore it was a ghost. We don t have proof that God exists, therefore he does not exist. -- Argument from ignorance: Using the lack of knowledge of any alternatives to justify the truth of a claim.

26 LINGUISTIC FALLACIES "I met the ambassador riding his horse. He was snorting and steaming, so I gave him a lump of sugar" "Helicopter powered by human flies" "The anthropologists went to a remote area and took photographs of some native women, but they weren't developed." "One morning I shot an elephant in my pajamas. How he got into my pajamas I'll never know." -- Groucho Marx -- Amphiboly: Sentence constructions are ambiguous; the whole meaning of a statement can be taken in more than one way.

27 *Inductive Fallacy Since I saw two people with the same birthday, then I think that this classroom has an unusual number of people with the same birthday. So, the next time I see two people with the same birthday, then it will confirm my hypothesis Confirmation Bias: Using future instances to confirm one s hypotheses, without appeal to independent evidence. Also, a tendency to search for or interpret new information in a way that confirms one's preconceptions. Avoiding information and interpretations which contradict 28 prior beliefs.

28 TWO CRITICAL THINKING ASSIGNMENTS. 3-5 PAGES each. Double spaced. 3. Write out a one-paragraph summary of the author s argument as it appears in your source. You may use quotes. The summary should outline the author s argument by indicating premises and conclusions. Remember, the conclusion is what the author wants you to believe and the premises are the reasons the author gives for why he wants you to believe his position. For example, if an author says, Sam Wellers should not move his bookstore from downtown, then that is the conclusion, and a premise might be Sam Weller s Bookstore will only be successful in downtown Salt Lake City. To make the argument a deductive argument, you might have to fill in an inference. In the example above, the inference will be: If Sam Wellers wants to be successful, he should not move his bookstore. If the author relies on unstated assumptions or unwanted consequences, then state these. Include everything relevant to your case. For each assignment, find one fallacious argument in the media. Your job is to catch people making mistakes in reasoning. Media includes television, newspaper editorials, talk radio shows, etc. A good place to look is the letters to the editor or public forum. 1. In your SHORT introduction, indicate the source of the argument. Name the author of the article and the article title, and then in parentheses list the newspaper with date and page of article. If you are using a hard copy, then clip out the article and attach it to your paper. If you are citing a website, then be sure to give the full URL in your bibliography. 2. Give a thesis statement (i.e. Joe blow made a Slippery Slope Fallacy. )

29 4. Identify and define the fallacy made. Fallacies can include affirming the consequent or denying the antecedent; or informal fallacies such as ad hominem, slippery slope, begging the question etc. A list of fallacies is given in Arthur s paper on E- reserves, and online, such as: In the longest section of your paper, you need to explain how the argument from your source fits the definition of the fallacy. This requires that you examine details of the author s argument and persuade me that the author really is making that fallacy. Pretend like I agree with the author and that I do not see anything wrong with the argument. Give examples or analogies to really show me that the argument is no good. Part of your job in defending your position is to persuade your reader that the fallacy you ve chosen really is a fallacy, using your target article as an example. You should feel like you are over-explaining the obvious. 6. A short conclusion will summarize your thesis. I.e. Joe Blow has made a slippery slope fallacy. 7. Include a bibliography.