Logical Fallacies - PowerPoint by honeycoma

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									Logical Fallacies

We Were Warned
Aristotle warned us to be wary of orators who attempt to appeal to our strongest emotions. Not only do we make mistakes in reasoning, we tend to seize on the mistakes that others make while failing to see the flaws in our own logic.

Types of errors
 Some are lapses in logical structure  Often hard to detect because we argue in everyday language, not chains of logical statements.  Common lapses:
    False, misleading imprecise statements Statements that appear to be true, but aren’t Statements that make illegitimate appeals Statements that do not fit the argument

Possible motives
 Carelessness  Misunderstanding  Ignorance  Deception Ultimately the motive affects how we respond to others’ arguments. An error in argument is called a Fallacy

What is a fallacy?
 A fallacy is a mistake in reasoning.  People often accept fallacies as legitimate argument.  Identification of fallacies is imprecise.  Fallacies tend to overlap.

About Fallacies…
 Rarely do we see our own arguments as fallacious.  Sometimes we reason fallaciously in judging someone else--example: you put aside someone else’s argument because you do not like them (ad hominem)

More about Fallacies…
Just because you recognize a fallacy in someone else’s argument does not mean you have trumped him. But there is the advantage in knowing where the other’s argument is weak. Beware, if you call someone on something, you may have to prove why their reasoning is fallacious.

Types of Fallacies
      Hasty Generalization Post Hoc Ergo, Propter Hoc (False Cause) Slippery Slope Straw Man False Analogy False Dilemma (Either/Or)

More Types of Fallacies
      Begging the question (circular reasoning) Non Sequitur Red Herring Complex Question Equivocation Ad Populum

And a few more…
      Appeal to Ignorance Ad Hominem Appeal Faulty Emotional Appeals Argument from Outrage Scapegoating Apple Polishing

Hasty Generalization
Making a general statement on the basis of an inadequate sample of evidence 1st: Sample A, which is too small, is taken from population B. Then: Conclusion C is drawn about Population B based on A. Reasoning: X% of all observed A's are B''s.Therefore X% of all A's are Bs. The fallacy is committed when not enough A's are observed to warrant the conclusion. If enough A's are observed then the reasoning is not fallacious.

Examples of Hasty Generalization
Smith, who is from England, decides to attend graduate school at Ohio State University. He has never been to the US before. The day after he arrives, he is walking back from an orientation session and sees two white (albino) squirrels chasing each other around a tree. In his next letter home, he tells his family that American squirrels are white. Sam is riding her bike in her home town in Maine, minding her own business. A station wagon comes up behind her and the driver starts beeping his horn and then tries to force her off the road. As he goes by, the driver yells "get on the sidewalk where you belong!" Sam sees that the car has Ohio plates and concludes that all Ohio drivers are jerks.

Post Hoc Ergo Propter Hoc
Latin for “After this, therefore because of this.” Also known as false cause, it has the following form: A occurs before B. Therefore, A is the cause of B Example: I had been doing pretty poorly this season. Then
my girlfriend gave me this neon laces for my spikes and I won my next three races. Those laces must be good luck...if I keep on wearing them I can't help but win.

Slippery Slope
Assumes that if a certain step is taken, a series of undesirable consequences will occur.
Event X has occurred (or will or might occur). Therefore event Y will inevitably happen.

Examples of Slippery Slope
 If students are allowed to drop courses late in the semester, there will be huge drop rates and pretty soon everyone will want to drop any course in which they will not receive an A.  "We've got to stop them from banning pornography. Once they start banning one form of literature, they will never stop. Next thing you know, they will be burning all the books!"

Straw Man
Presenting an extreme or weak case as an example of the argument being refuted.
Person A has position X. Person B presents position Y (which is a distorted version of X). Person B attacks position Y. Therefore X is false/incorrect/flawed.

Examples of Straw Man
 Those who argue for the elimination of the SAT want to fill our colleges with unqualified students.  Anyone who supports the proposal to build the new highway through our county is voting for the end of our rural way of life.

And One More…
 Observers, ranging from psychiatrists to parents, have noticed that people who smoke several joints a day often lack motivation to work, study, exercise, or indeed to do much more than sit around and listen to music.According to these observers, then, sitting around and listening to music are regarded as if they are behaviorally meaningless. But what's wrong with sitting in a cool room on a hot summer's day, listening to Tchaikovsky after smoking a joint? Notice how the writer shifts the original objection to pot smoking to a list of less offensive behaviors.

False Analogy
Goes beyond pointing out a resemblance between two things or situations to claim that the things or situations are the same or call for the same response. In an analogy, two objects (or events), A and B are shown to be similar. Then it is argued that since A has property P, so also B must have property P. An analogy fails when the two objects, A and B, are different in a way which affects whether they both have property P. This kind of fallacy is proven by identifying the two objects or events being compared and the property which both are said to possess and showing how that the two objects are different in a way which will affect whether they both have that property.

Examples of False Analogy
 Employees are like nails. Just as nails must be hit in the head in order to make them work, so must employees.  Government is like business, so just as business must be sensitive primarily to the bottom line, so also must government. (But the objectives of government and business are
completely different, so probably they will have to meet different criteria.)  Andhttp://www.juancole.com/2005/12/43-killed-70-wounded-by-busbomber-and.html

False Dilemma
Arguing that there are only two choices in a situation and that one choice is the correct one because the other is unthinkable. Only in cases where there are only two options is the reasoning valid. Uses the following pattern of reasoning: Either claim X is true or claim Y is true (when X and Y could both be false). Claim Y is false. Therefore claim X is true. This is fallacious reasoning because both claims could be false, so you cannot infer that if one is true if the other is false. Either 1+4 =7 or 1+4=12 1+4 does not equal 7 Therefore, 1+4=12 (Doesn’t work)

Examples of False Dilemma
 You’re either for the war or you’re a traitor.  Since science is not absolutely certain of many of its claims and does make mistakes, mysticism must be correct.  Either we pass a curfew or juvenile crime will soar.

Begging the Question
Also known as “circular argument,” it is an argument that either assumes exactly what is to be established or restates its conclusion in different words so that it looks like reason.
X is true. The evidence for this claim is that X is true. If such actions were not illegal, then they would not be prohibited by the law. "Paranormal phenomena exist because I have had experiences that can only be described as paranormal.” http://www.poynter.org/column.asp?id=1&aid=39197

Non Sequitur
Literally, it does not follow, it is a response that has no relevance to what preceded it, or to a conclusion that does not follow from the premises. http://www.mahablog.com/2006/08/14/nonsequiturs/

Red Herring
 An argument intended to divert attention away from the real issue, a false clue intended to mislead.  The basic idea is to "win" an argument by leading attention away from the argument and to another topic.  From the idea that rubbing a herring across a trail will cause a dog to leave the initial trail and search for the herring.

Structure of a Red Herring
Topic A is under discussion. Topic B is introduced under the guise of being relevant to topic A (when topic B is actually not relevant to topic A) Topic A is abandoned.
Changing the topic cannot count as an argument against a claim.

Examples of Red Herring
 When Bill Clinton shot missiles at Sudan, he was accused of creating a red herring to distract people from the Monica Lewinsky charges.  A reporter asks a Homeland Security officer if his office has made America safer, saying that the polls show that this not the case. His response: We are making progress towards reassuring people, but unfortunately our efforts have been hampered by the tendency of the press to concentrate on the negative side of the issue. The blame is shifted away from his office and onto the press.

The Chewbacca Defense
 http://images.southpar kstudios.com/media/so unds/214/214_chewba cca.wav

Complex Question
 The argument takes the form of a question often a rhetorical question. Answering the question, however, is impossible, unless something is taken for granted that still ought to be regarded as doubtful. Answering the question amounts to admitting something that should not be admitted.

Complex Question
 Since a complex question cannot be answered (as asked), the opponent is left unable to answer without hurting his own argument one way or the other. It is fallacious because some conclusion is drawn from the opponent's inability to answer the question. In most cases this conclusion is left unstated (except, perhaps, in the minds of listeners).  Some argue that it is not so much an argument as a manner in which to trip up your opponent.

Complex Question Examples
 Have you stopped beating your wife? Only two possible answers:
1."Yes, I have stopped beating my wife", which entails "I was beating my wife. "2."No, I haven't stopped beating my wife", which entails "I am still beating my wife."

 When are you going to start acting like a responsible adult? (By asking for a time the change will occur,
the questioner makes it appear that both you are not acting responsibly and you need to change)

Equivocation
 Also known as doublespeak  Shifts the definition of a key term within an argument.  Usually occurs over an extended text and may not be immediately obvious.  An argument of ambiguity

Examples
 I know that everyone is in favor of keeping our neighborhood safe. So I am sure you will all agree with me that we need to put a chain link fence around it to ensure safety.(There may be a shared commonsense understanding of what
safe is, but not all may agree that it includes a fence.)

 I know that John Keats is one of the Romantic Poets. It’s surprising, then, that his “Ode to Autumn” is all about the season and has nothing to do with relationships between men and women. (Two different meanings of the word “romantic” are
operating here: one refers to a type of early nineteenth century English poetry, the other to relations between people attracted to each other.)

 Everyone should fight for what they believe in. You disagree with my beliefs, so I'm going to punch you in the nose.

Ad Populum
 Means to the people  Appeal to popularity  Appeals to the popular opinion or the popular belief or the opinions of those who are popular rather than those who are knowledgeable. Most people approve of X, therefore X is true.

Examples
 You should by this car because Tiger Woods says so.  It is acceptable to lie because everyone does it.  My fellow Americans...there has been some talk that the government is overstepping its bounds by allowing police to enter peoples' homes without the warrants traditionally required by the Constitution. However, these are dangerous times and dangerous times require appropriate actions. I have in my office thousands of letters from people who let me know, in no uncertain terms, that they heartily endorse the war against crime in these United States. Because of this overwhelming approval, it is evident that the police are doing the right thing.

Appeal to Ignorance
 Bases an argument on the absence of evidence or evidence that cannot examined.  Proposition A is not known(proved) to be true (false), therefore A is true (false).  Arguments of this form assume that since something has not been proven false, it is therefore true. Conversely, such an argument may assume that since something has not been proven true, it is therefore false.

Examples
 [Joe McCarthy] announced that he had penetrated "Truman's iron curtain of secrecy" and that he proposed forthwith to present 81 cases…Cases of exactly what? "I am only giving the Senate," he said, "cases in which it is clear there is a definite Communist connection…persons whom I consider to be Communists in the State Department." …Of Case 40, he said, "I do not have much information on this except the general statement of the agency…that there is nothing in the files to disprove his Communist connections."Source: Richard H. Rovere, Senator Joe

McCarthy (Methuen, 1960), pp. 106-107. Cited in: Irving M. Copi, Introduction to Logic (Fourth Edition) (1972), p. 88.

A couple more…
You cannot prove that God does not exist, so He does." You cannot prove that God exists, therefore He doesn’t. Since scientists cannot prove that global warming will occur, it probably won't. To prove:Identify the proposition in question. Argue that it may be true even though we don't know whether it is or isn't.

Ad Hominem Appeal
 Literally means to the man  Any argument that attacks the character of the person rather than the substance of what that person has said on an issue
Person A makes claim X. Person B makes an attack on person A. Therefore A's claim is false. Fallacious in that the character, circumstances, or actions of a person do not (in most cases) have a bearing on the truth or falsity of the claim being made (or the quality of the argument being made).

Examples of Ad Hominem
 "If they don't have the guts to come up here in front of you and say, 'I don't want to represent you, I want to represent those special interests, the unions, the trial lawyers' ... if they don't have the guts, I call them girlie men."--Arnold Schwarzenegger (2004, referring to members of the California legislature)  You can’t give any credit to Jack’s claim; he doesn’t even have a job.  Dr. Bob’s advice about stopping smoking is worthless. He smokes himself.

Faulty Emotional Appeals
 Relies on emotional appeals in the absence of reason.  Favorable emotions are associated with X, therefore X is true.

Examples
 You have to give me a B or I will lose my scholarship and my grandmother will be devastated.  The new PowerTangerine computer gives you the power you need. If you buy one, people will envy your power. They will look up to you and wish they were just like you. You will know the true joy of power. TangerinePower.

Places to Find Fallacy Info
 The Nizkor Project  Logical Fallacies  A List of Common Fallacies


								
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