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Logical Fallacies.

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Presentation on theme: "Logical Fallacies."— Presentation transcript:

1 Logical Fallacies

2 What are Fallacies? First the Word family
Fallacy (noun) Fallacious (adjective) Synonyms: misconception, false, unreasonable, deception, delusion, misapprehension. Logical fallacies are flaws in reasoning that lead to faulty, illogical statements. They are unreasonable argumentative tactics named for what has gone wrong during the reasoning process.

3 What are Fallacies? Often during the course of constructing an argument, we fall into the trap of a logical fallacy. These mistakes in reasoning seriously affect our ability to argue effectively. Sometimes we fool ourselves into believing that a faulty argument is sound or reasonable; other times we deliberately use a flawed argument for the sake of winning the battle. In any case, we should be aware that logical fallacies obscure the truth. Use the list provided of logical fallacies to identify them in your writing and the writing of others. NOTE: Most logical fallacies masquerade as reasonable statements, but they are in fact attempts to manipulate readers by reaching their emotions instead of their intellects.

4 But first: a few terms… Logic – The science of correct reasoning.
Reasoning – The drawing of inferences or conclusions from known or assumed facts. There are two main types of Reasoning: Deductive and Inductive

5 Deductive vs. Inductive Reasoning
Deductive Reasoning – A type of logic in which one goes from a general statement to a specific instance. The classic example All men are mortal. (major premise) Socrates is a man. (minor premise) Therefore, Socrates is mortal. (conclusion) The above is an example of a syllogism. And a syllogism is pretty much foolproof. Another Example: All students eat pizza. Claire is a student at ASU. Therefore, Claire eats pizza.

6 Inductive Reasoning Inductive Reasoning involves going from a series of specific cases to a general statement. The conclusion in an inductive argument is never guaranteed. But it is REASONABLE. Example: What is the next number in the sequence 6, 13, 20, 27,… There is more than one correct answer. Here’s the sequence again 6, 13, 20, 27… Look at the difference of each term. 13 – 6 = 7, 20 – 13 = 7, 27 – 20 = 7 Thus the next term is 34, because 34 – 27 = 7. However what if the sequence represents the dates. Then the next number could be 3 (31 days in a month). The next number could be 4 (30 day month) Or it could be 5 (29 day month – Feb. Leap year) Or even 6 (28 day month – Feb.)

7 Just Remember this… The key to inductive Reasoning is whether or not your conclusion is REASONABLE not valid. In your essay (for the most part) you are concerned with using inductive reasoning—making logical and reasonable generalizations or comparisons You are going from the specific to the general You may go from the general to the specific but not often

8 Where do I look in my own essay for fallacies?
Everywhere but mainly… In your evidence but especially your warrants (implicit and explicit) Setting up the counterargument (see Straw Man fallacy)

9 Lets look at the Logical Fallacies handout and point out specific ones you should focus on
Hasty Generalizations base an argument on insufficient evidence. Writers may draw conclusions too quickly, not considering the whole issue. They may look only at a small group as representative of the whole or may look only at a small piece of the issue. Example: Concluding that all fraternities are party houses because you have seen three parties at one fraternity is a hasty generalization. The evidence is too limited to draw an adequate conclusion. Example: With this technology, the government, or anyone in the world, is able to look right into your backyard. Solution: add a qualifier… With this technology, the government, or anyone in the world, may able to look right into your backyard at some point in the foreseeable future.

10 Fallacies Cont. Post Hoc, (after this, therefore also this) arguments, or post hoc for short, assume a faulty causal relationship. One event following another in time does not mean that the first event caused the later event. Writers must be able to prove that one event caused another event and did not simply follow in time. Because the cause is often in question in this fallacy, we sometimes call it a false cause fallacy. Example: "Eating five candy bars and drinking two sodas before a test helps me get better grades. I did that and got an A on my last test in history." This arguer ignores other possible causes like how much he had studied and how easy the test was.

11 Fallacies Cont. Opposing a Straw Man is a tactic used by a lot of writers because they find it easier to refute an oversimplified opposition. Writers may also pick only the opposition’s weakest or most insignificant point to refute. Doing so diverts attention from the real issues and rarely, if ever, leads to resolution or truth. Example: The debate over drink machines centers around cost and choice. Opponents of the new drink machines bring up their location as an important issue. This insignificant point has little relevance to the actual issues.

12 Fallacies Cont. Slippery Slopes suggest that one step will inevitably lead to more, eventually negative steps. While sometimes the results may be negative, the slippery slope argues that the descent is inevitable and unalterable. Stirring up emotions against the downward slipping, this fallacy can be avoided by providing solid evidence of the eventuality rather than speculation. Example: "If we force public elementary school pupils to wear uniforms, eventually we will require middle school students to wear uniforms. If we require middle school students to wear uniforms, high school requirements aren’t far off. Eventually even college students who attend state-funded, public universities will be forced to wear uniforms.” Example: In reality, live streaming makes a criminal’s job much easier. A burglar now knows when nobody's home, someone who wants to kidnap children now knows that certain kids play in the backyard when the parents are gone, and a stalker can now stalk from the comfort of their own home.

13 Fallacies Cont. False Authority is a tactic used by many writers, especially in advertising. An authority in one field may know nothing of another field. Being knowledgeable in one area doesn’t constitute knowledge in other areas. Example: A popular sports star may know a lot about football, but very little about shaving cream. His expertise on the playing field does not qualify him to intelligently discuss the benefits of aloe.

14 Fallacies Cont. Red Herrings have little relevance to the argument at hand. Desperate arguers often try to change the ground of the argument by changing the subject. The new subject may be related to the original argument, but does little to resolve it. More specifically, this fallacy suggests that a person should not be held accountable for actions because another person or persons are doing something just as bad or worse. Example: "Winthrop should pave the lot behind Dinkins. Besides, I can never find a parking space on campus anyway." The writer has changed the focus of the argument from paving to the scarcity of parking spaces, two ideas that may be related, but are not the same argument.

15 Fallacies Cont. Appeal to Emotion (Fear) is when you attempt to manipulate an emotional response in place of a valid or compelling argument. Appeals to emotion include appeals to fear, envy, hatred, pity, pride, and more. It's important to note that sometimes a logically coherent argument may inspire emotion or have an emotional aspect, but the problem and fallacy occurs when emotion is used instead of a logical argument, or to obscure the fact that no compelling rational reason exists for one's position. Everyone, bar sociopaths, is affected by emotion, and so appeals to emotion are a very common and effective argument tactic, but they're ultimately flawed, dishonest, and tend to make one's opponents justifiably emotional. Example: Luke didn't want to eat his sheep's brains with chopped liver and brussel sprouts, but his father told him to think about the poor, starving children in a third world country who weren't fortunate enough to have any food at all. Example: Do you want everyone to be able to see every little detail in your backyard, or even through your window? Real time video surveillance gives anyone the ability to watch your kids swimming in your backyard.


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