Logical Fallacies and Arguments

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Logical Fallacies and Arguments. Learning. Exercises. Definitions of Fallacies. Identifying Logical Fallacies. Creating Logical Fallacies. Continuums of Logic. Easily Confused Fallacies. Overlapping Fallacies & the Red Herring Class. Fallacies of Simplicity. Fallacies of Relevance. - PowerPoint PPT Presentation

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Logical Fallacies and Arguments

Logical Fallacies and ArgumentsDefinitions of FallaciesContinuums of LogicEasily Confused FallaciesOverlapping Fallacies & the Red Herring Class Identifying Logical FallaciesCreating Logical FallaciesLearningExercises1Fallacies of SimplicityFallacyDefinitionConcise VersionExampleHasty GeneralizationDrawing a conclusion about a large group based on a few or on little evidenceOverstatement; stereotypeI saw a fight at a fraternity party last weekend. Those frat boys are out of control.Forced HypothesisThe explanation (hypothesis) offered for a situation is forced because it draws its conclusions from insufficient evidence or misinterprets the evidencePoorly supported hypothesisJerry and Kim live next door to each other, so they must be really good friends.Non SequiterComing to a conclusion that doesnt logically follow the explanation.Idea doesnt followWe dont see as many women in calculus classes as we do men, so clearly their brains are not capable of handling difficult math concepts.Slippery SlopeSuggesting that one step will inevitably lead to more and more negative steps; often appears as A will lead to B, B will lead to C, C will lead to D... Progression of negative consequences

You can never give anyone a break. If you do, they'll walk all over you.False DilemmaReducing complex issues to black and white polarized positionsOnly 2 alternatives;Either / or"Wouldn't you rather have a park than a storage facility for nuclear waste?"False AnalogyUsing a comparison to relate two ideas that are not so similarComparing 2 incomparable thingsEmployees are like nails. Just as nails must be hit in the head in order to make them work, so must employees. Post Hoc FallacyAssuming that because one thing came before another, it caused the other to occur, without logically linking the two.Faulty causal relationshipI ate a cheeseburger before the test and made an A. Cheeseburgers must help me think better.2Analogy False AnalogyComparisons help elucidate new ideas and solutions for issues, but they can also take us so far away from the issue at hand that they become irrelevant. How similar are the two things compared? How different are they? Is the comparison effective or ineffective?

1) Drinking and marijuana2) Child obesity and child abuse

4Causal Relationship Post HocScientists and lay people alike try to discern which factors cause certain effects, and there is often debate over how logical these assertions are.

How closely related do the items seem? What evidence suggests that there is a causal relationship between them.

1) It rains on campus. Student attendance decreases.

2) If youd been a better teacher, I would have learned the material better.

5Generalization Hasty Generalization We often employ generalizations to form patterns and make sense of the world. But this strategy can have detrimental effects when we dont acknowledge that people often fall outside the majority and that many stereotypes have no legitimate basis in reality.

Is the generalization backed by evidence? For what purposes is the group generalized?

1) Most English majors are Democrats.

2) Only women are good at English.

6Stating the Counterargument Straw ManIn debates, stating the position of the counterargument reveals that you understand their points and gives you a common place from which to begin the debate. However, using this strategy to misrepresent and dumb down the opposition is a deliberate approach to argument that will take you away from the real issues.

What are the key points in the counterargument? How does this misrepresent or dumb down their argument?

1) The people who say obesity is a social problem, and not an individual one, think that we can never overcome the brainwashing of advertisements.

2) Gun control advocates want to take away every gun in America.7Character Evidence Ad HominemEven in court rooms, we often find it useful to establish the character or credibility of a witness or defendant. However, when this character analysis has little to do with the issue and simply attacks the person in an attempt to discredit him or her, we have done little to logically advance our argument.

Are the points about his/ her character relevant to the debate? Does it make them legitimately less able to comment or perform in the debate?

1) Dont appoint him designated driver. Hes had a DUI before.

2)Dont believe what he says. Hes had a DUI before.

8Agreed Upon Conventions BandwagonIn some realms, such as scientific research, reproducing the same results provides validity for an argument. When the preponderance of evidence and experts suggest that something is valid, then we often accept this majority opinion. However, many issues cannot be measured this way and the assent of the majority provides no basis for why an opinion is valid.

Is the majority a group of experts who have the knowledge to comment on the topic?

1) 7 out of 10 psychologists recommend drug intervention for severe cases of depression.

2) 7 out of 10 college students think its acceptable to cheat on quizzes and tests.

9Easily Confused FallaciesMany logical fallacies are closely related, but have fine-tuned difference between them. Here are some ways to distinguish between the more popularly confused fallacies.BandwagonAd PopulumAppealing to common actions; everyones doing itAppealing to common values; everyone believes itEx) Most educated people vote; 10,000 people pray dailyEx) Everyone loves dogs; Americans want their freedoms.Straw ManAd HominemMaking their argument look stupidMaking the person look stupidEx) Proponents of legalizing marijuana argue weed is no different than oregano.Ex) Proponents of legalizing marijuana are lazy potheads.Forced HypothesisPost HocPoor understanding of the evidence-claim relationshipPoor understanding of the temporal (in time) cause-effect relationshipEx) Dr. Jay is a good teacher because he gives As.Ex) Dr. Jay is a good teacher because he ate a sound breakfast.10Overlapping FallaciesThese fallacies often occur together because they are so closely related or because they can describe the same kind of faulty logic.

Hasty GeneralizationAd HominemAttacking a person often means stereotyping them.Ex) Hes clearly lying. Criminals have no idea what honesty is.Non SequiterRed HerringBoth often provide evidence that is off-topic.Ex) Donna will make an A in physics because she made an A in biology. (Note: This is also a false analogy.)Non SequiterPost HocBoth often establish a faulty cause-effect relationship.Ex) College students watch less TV because the screens have gotten too big.Red HerringForced HypothesisBoth often provide a claim based on evidence that cannot justify it. Ex) Dr. Jay is a good teacher because he loves the university.His love of the university is both a faulty piece of evidence for the claim and is a side-issue.11Red Herring ClassAll of the following fallacies are attempts to take the debate off-topic and to avoid supporting ones argument with logical evidence, making them categorizable as red herrings. But when identifying these fallacies, the more specific classes below will tell you more about the fallacy than simply calling it an off-topic red herring.

Straw man: distract opponents by misrepresenting their positionBandwagon: distract opponents by calling them to join the groupAd Populum: distract opponents by appealing to common valuesAd Hominem: distract opponents by demeaning their character12Directions: Identify the logical fallacies in the following statements. As you have learned, statements can often be classified in more than one way.

Identifying Logical FallaciesAll of my friends drink energy drinks. They are totally safe.If we allow guns on campus, there will be more school shootings and massacres. Sylvestor Stallone is endorsing McCain. We need a tough president. Oprah Winfrey is voting for Obama. She knows so much about America and what is good for us. She really cares about the poor.Rush Limbaugh is a fat, angry slob. I cant believe anyone listens to him. Michael Moore is a fat, angry slob. I cant believe anyone listens to him.No one should die because they cannot afford health care, and no one should go broke because they get sick. If you agree, join us in posting this as your status for the rest of the day.Id rather go naked than wear fur. The Social Security system works just fine. I get my check every month.13Identifying Logical FallaciesAll my friends drink energy drinks. They are totally safe.

Friends are a small sample. Not enough evidence to draw a logical conclusion. Hasty Generalization. Bandwagon.

Identifying Logical FallaciesVote or Die.

If we dont vote, we wont actually die.

False Dilemma.Identifying Logical FallaciesIf we allow guns on campus, there will be more school shootings and massacres.

If we dont allow guns on campus, there will be more school shootings and massacres. Both sides must prove link between guns on campus and increased shootings. Slippery Slope. Ad Populum.

Identifying Logical FallaciesSylvestor Stallone is endorsing McCain. Stallone is tough and we need a tough president.

Oprah Winfrey is voting for Obama. She knows so much about America and what is good for us. She really cares about the poor.

Celebrity endorsement is effective advertisement, but not logical! A persons fame has no relevance to the quality of the product being endorsed.Ad Populum.Identifying Logical FallaciesRush Limbaugh is a fat, angry slob. I cant believe anyone listens to him.Michael Moore is a fat, angry slob. I cant believe anyone listens to him.

Attack through name callingAd Hominem

Identifying Logical FallaciesNo one should die because they cannot afford health care, and no one should go broke because they get sick. If you agree, join us in posting this as your status for the rest of the day.

Hospitals do treat emergency cases and county hospitals deliver babies, even without patients proof of insurance. Most areas have a free/low-cost clinic. There are options for low-cost insurance, or people can pay out of pocket.False Dilemma. Hasty Generalization. Begging the Question.Identifying Logical FallaciesId rather go naked than wear fur.

Nudity does nothing to protect harmed animals. Effectiveness of slogan based entirely on shock value (and attractive models!). Non Sequitur. Ad Populum.

Identifying Logical FallaciesThe Social Security system works just fine. I get my check every month.

Effectiveness of a system is not determined by one example. History of payments does not guarantee future payments, if there is no money to replace what is spent.Hasty Generalization. Forced Hypothesis.Identifying Logical FallaciesThose protestors at Planned Parenthood are extremists who want to take away women's rights.

Misrepresents opponents position. Ignores difference in defining terms (right vs. privilege). Use of extremist marginalizes the group to make them seem less significant. Straw ManIdentifying Logical FallaciesEvery child a wanted child.

It is possible to have mixed emotions (wanting and not-wanting at the same time). It is possible to move from not wanting to wanting. Most Americans oppose countries who eliminate populations of unwanted people (Nazi Germany, Rwanda). Overstatement. False Dilemma.