common errors in reasoning that undermine the logic of an - PowerPoint Presentation

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common errors in reasoning that undermine the logic of an argument illegitimate, controversial arguments or irrelevant points designed to enflame an audience often identified because they lack adequate evidence to support a claim

Fallacies

are

:Slide2

Why do they matter?Avoid logical fallacies in your own writing – and be on the lookout for them in the arguments of others! Reasonable texts by credible writers have nothing to hide. They name names, identify sources, and generate appropriate emotions. Slide3

FallacyMisconceptionErroneous BeliefMythIncorrect reasoningBlurt out (regrettable)Lie or misleading notionSlide4

Fallacy #1: Slippery SlopeEmotionally driven (scare tactics)This is an argument, without solid reason, that taking one step will inevitably lead to an undesirable step. Ex. If you don’t come home at 10PM, all manner of terrible crimes will be committed against you. http://www.youtube.com/watch?v=K-wQI58szGwCan you think of another example?Slide5

Fallacy #2: Either/OrEmotionally driven (obscuring in nature)This is a conclusion that oversimplifies the argument by reducing it to only two sides or choices. Ex. We can either stop using cars or continue to destroy the Earth.Can you think of any other examples?Slide6

Fallacy #3: Hasty GeneralizationLogical (dangerous in its seeming naturalness)This involves rushing to a conclusion without sufficient evidence.Ex. The French are snobby and rude. Remember those two kids from Biology with the awful manners? Yeah, they were French. I rest my case. Ex. Even though it’s the first day, I can tell this class is going to be so boring. Can you think of another example?Slide7

Fallacy #4: The Straw ManLogical (makes an argument “easier” and “obvious”)This oversimplifies the opponent’s viewpoint, then attacks the simplified (and often inaccurate) argument. Ex. People who do not support raising minimum wage hate poor people and teenagers.http://www.youtube.com/watch?v=xFVUjVPHZEY&feature=relatedhttp://www.youtube.com/watch?v=fCOhJNfWMq8&feature=relatedCan you think of an example?Slide8

Fallacy # 5: Red HerringLogical and emotionally driven (out of the blue information)This is a diversionary tactic. It avoids the key issues by avoiding an argument rather than addressing it. This avoidance is secured by introducing irrelevant and often emotionally intense information. Ex. The level of radioactive contamination in seafood may be unsafe but what will all those Pacific fishers do to support their little sons and daughters?Can you think of an example?Non-sequitur – doesn’t logically follow; out of sequence If you loved me, you’d buy me a bicycle! Slide9

Logical Fallacy #6: Ad Hominem (Attack on Personal Character)Ethos driven (destroys credibility)This is a straight up attack on the character of an individual person rather than his or her opinion or argument. Ex. You cannot believe anything she says about welfare reform. You know she’s just a bleeding heart liberal/cold-hearted conservative. Ex. I don’t ever listen to environmentalists. They are just dirty, dirty hippies with nothing better to do.

http://www.youtube.com/watch?v=lyiuqYO9tV8&feature=related

Can you think of an example?Slide10

Logical Fallacy #7: Ad Populism (Appeal to Popular Beliefs)Ethos and logos driven (truth is self-evident)This is an appeal that speaks to positive or negative concepts rather than the real issue at hand. Ex. If you were a real American, you would support the rights of people to drive whatever car they want to drive. Ex. If you were a real American, you would support the rights of people to exist in a pollution free environment.

Can you think of an example?Slide11

Logical Fallacy #8: Moral Equivalence: Ethos driven (faulty comparison)This fallacy compares minor misdeeds with larger issues.Ex. That parking attendant who gave me a ticket is as bad as Hitler.Ex. Yes, I used illegal funds in my campaign – but so did my opponent!Can you think of an example?Slide12

How can you revise Fallacies out of your own writing?Pretend you disagree with the conclusion you're defending. What parts of the argument would now seem fishy to you? What parts would seem easiest to attack?

Give special attention to strengthening these parts.

List your main points

; under each one,

list the evidence

you have for it.

Seeing your claims and evidence laid out this way may make you realize that you have no good evidence for a particular claim, or it may help you look more critically at the evidence you're using.

Learn which types of fallacies you're especially prone to

, and be careful to check for them in your work.

Some writers make lots of appeals to authority; others are more likely to rely on hasty generalizations or set up straw men.

Read over some of your old papers to see if there's a particular kind of fallacy you need to watch out for.

Be aware that broad claims need more proof than narrow ones

.

Claims that use sweeping words like "all," "no," "none," "every," "always," "never," "no one," and "everyone" are sometimes appropriate—but they require a lot more proof than less-sweeping claims that use words like "some," "many," "few," "sometimes," "usually," and so forth.

Double check your characterizations of others

Be sure you are accurately representing your opponents Slide13

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