Ling 21 - Lecture 7 - Logical Fallacies II

Ling 21 - Lecture 7 - Logical Fallacies II - L ing 21, L...

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Unformatted text preview: L ing 21, L ect ur e 7: Logical Fallacies II: Fallacies of Insufficient Evidence In this chapter, you should … In understand that a fallacy of insufficient understand evidence occurs when an arguer fails to provide sufficient evidence for the conclusion. In this chapter, you should also … In understand and be able to identify the understand following fallacies of relevance: Inappropriate appeal to authority Appeal to ignorance False alternatives Loaded questions Questionable cause Hasty generalization Slippery slope Weak analogy Inconsistency Inconsistency Inappropriate Appeal to Authority: Authority This fallacy occurs when an arguer cites This an authority who, there is good reason to believe, is unreliable. You should recognize the following instances of inappropriate appeals to authority: When the source cited is not a genuine authority on the subject under consideration. When there is reason to believe that the source is biased. When the accuracy of the source's observations is questionable. When the source cited (e.g. a media source, reference work, or Internet source) is known to be generally unreliable. When the source has not been cited correctly or the cited claim has been Inappropriate Appeal to Authority: Authority Hi, I’m heavyweight boxing champ Buster Hi, Brawler. After a tough night in the ring, my face needs some tender loving care. Lather-X Sensitive Skin Shaving Gel. You can’t get a smoother, closer shave. can’t Source is not an authority on skin care. Inappropriate Appeal to Authority: Authority Ned Bumpley has been paid $100,000 by the Ned Sensational Enquirer tabloid for his story that he is Bill Gate’s illegitimate son. Given Mr. Bumpley’s reputation for honesty, I think we should believe him, even tough he has produced no corroborating evidence and DNA tests fail to support his claim. support The source is biased, with an obvious motive to lie. Inappropriate Appeal to Authority: Authority After taking LSD and drinking seven After beers, Jill claims she has a conversation with Elvis’ ghost in the alley behind McDearmon’s Bar. I’ve never known Jill to lie. So, I think we should believe her. lie. There is reason to doubt the reliability of the There witness’s observations. witness’s Inappropriate Appeal to Authority: Authority Most immigrants who enter this country Most wind up in jail or on welfare. I know this because I read it on a White Power Web site. site. The source is known to be generally The unreliable. unreliable. Inappropriate Appeal to Authority: Authority It states in the Constitution that there must It be a ‘wall of separation’ between church and state. Publicly funded school vouchers clearly violate this wall of separation. Therefore, publicly funded school vouchers are unconstitutional. school The Constitution does not use the phrase ‘wall The of separation’ between church and state. of Inappropriate Appeal to Authority: Authority Dr. Duane Gish, a biochemist with a Ph.D. from Dr. Berkeley and senior vice president of the Institute for Creation Research, has argued that there is no credible evidence supporting the theory of evolution. In view of Dr. Gish’s expertise on this subject, we should conclude that evolution is a myth. that The claim conflicts with the overwhelming opinion of The most experts in the field. most Inappropriate Appeal to Authority: Authority Dr. Stanford P. Higginbotham, a leading social Dr. philosopher, has argued that capital punishment is always morally wrong. Given Dr, Higginbotham’s impressive credentials, we should conclude that capital punishment is always morally wrong. The source’s claim cannot be settled by an appeal to The expert opinion – no expert consensus exists. expert Inappropriate Appeal to Authority: Authority Old Doc Perkins says he has an eighty-year- old friend who can run a 100-yard dash in old less than ten seconds. Old Doc is one of the most trusted members of this community. So if Old Doc says he has an eighty-year-old friend who can run a 100-yard dash in less than ten seconds, I, for one, believe him. than The claim is so improbable it should be rejected. The Appeal to Ignorance: Appeal The arguer asserts that a claim must be The true because no one has proven it false, or conversely or The arguer asserts that a claim must be The false because no one has proven it to be true. true. Appeal to Ignorance: Appeal There must be intelligent life on other There planets. No one has proven that there isn’t. planets. There isn’t any intelligent life on other There planets. No one has proven that there is. planets. Both claims suffer from the basic flaw that they Both assume that the lack of evidence for (or against) the claim is good reason to believe that the claim is false (or true). claim Appeal to Ignorance: Appeal Exceptions: Sometimes the fact that a search hasn’t found Sometimes hasn’t something is good evidence that the thing isn’t there to be found (e.g., medical trials). there A careful search has been conducted, and careful and It is likely that the search would have found It something is there had been anything there to be found. found. Special rules require a claim to be rejected as Special false unless a certain burden of proof is met. false Innocent until proven guilty beyond a reasonable Innocent doubt. doubt. False Alternatives: False This fallacy is committed when an arguer This poses a false dichotomy. Either we elect a Republican as president, Either or crime rates will skyrocket. Obviously, we don’t want crime rates to skyrocket. Therefore, we should elect a Republican as president. as Loaded Question: Loaded This fallacy is committed when an arguer This asks a question that contains an unwarranted assumption. unwarranted When did you stop beating your wife? When Where did you hide the body? Why do you always act like a total jerk Why whenever you’re around my ex-boyfriend? whenever Did you write this immoral trash? Questionable Cause: Questionable This fallacy occurs when an arguer gives This insufficient evidence for a claim that one thing is the cause of another. You should recognize the following instances of Questionable Cause: Post hoc fallacy Mere correlation fallacy Oversimplified cause fallacy Questionable Cause 1: Questionable Post hoc fallacy: This fallacy occurs This when an arguer assumes, without adequate reason, that because one event precedes another, that the first event was the cause of the second. event How do I know that ginseng tea is a cure for How the common cold? Last week I has a bad case of the sniffles. I drank a cup of ginseng tea, and the next morning my sniffles were gone. Questionable Cause 2: Questionable Mere correlation fallacy: This fallacy This occurs when an arguer assumes, without adequate reason, that because two conditions or events regularly occur together, that there must be a causal relationship between them. Every spring we sacrifice a virgin to the sun Every god, and every spring the life-giving rains come. Therefore, sacrificing a virgin to the sun god causes the life-giving rains to come. sun Questionable Cause 3: Questionable Oversimplified cause fallacy: This This fallacy occurs when an arguer assumes, without sufficient evidence, that a single condition or event is the sole cause of some effect, when there are in fact other contributing causes. SAT scores have fallen sharply since the SAT 1960s. Clearly, students are watching too much TV. much Hasty Generalization: Hasty This fallacy occurs when an arguer draws a This general conclusion from a sample that is either biased or too small. • • • • A biased sample is one that is not representative of the biased target population. target The target population is the group of people or things The target that the generalization is about. Hasty generalizations can often lead to false Hasty stereotypes. stereotypes I’ve hired three business majors as student help in the I’ve past year. All three were lazy and shiftless. Obviously all business majors are lazy and shiftless. business Slippery Slope: Slippery An arguer commits this fallacy when they claim, An without sufficient reason, that a seemingly harmless action will lead to a disastrous outcome. Bans on so-called assault weapons must be Bans vigorously opposed. Once the gun-grabbing liberals have outlawed assault weapons, next they’ll go after handguns. After that, it will be shotguns and semiautomatic hunting rifles. In the end, law-abiding citizens will be left totally defenseless against predatory criminals and a tyrannical government. predatory Slippery Slope: Slippery Slippery slope arguments generally follow this Slippery pattern: The arguer claims that if a certain seemingly The harmless action, A, is permitted, A will lead to B, B will lead to C, and so on to D. The arguer holds that D is a terrible thing and The therefore should not be permitted. In fact, there is no good reason to believe that A In will actually lead to D. will Weak Analogy: Weak When the conclusion of an argument When depends upon a comparison between two (or more) things that are not similar in relevant respects, the fallacy of weak analogy is committed. committed. Why does a family who has no children in a school district have to pay school taxes? This is like paying cigarette taxes even though you don’t smoke. smoke. Weak Analogy: Weak This fallacy generally follows the pattern: This A has characteristics w, x, y, and z. has B has characteristics w, x, and y. has Therefore, B probably has characteristic z, too. Therefore, But characteristics w, x, and y are not relevant But to z or A and B have differences relevant to z which are and ignored by the arguer. ignored Inconsistency: Inconsistency This fallacy occurs when an arguer asserts This inconsistent premises, asserts a premise that is inconsistent with his or her conclusion, or argues for inconsistent conclusions. conclusions. Mickey Mantle: Hey, Yogi, what do you say we Mickey eat at Toots’ tonight? eat Yogi Berra: That place is old news. Yogi Nobody goes there anymore. It’s too crowded. crowded. Chapter 6 Logical Fallacies-II Fallacies-II What's to say against [cigars]? They killed George Burns at 100. If he hadn't smoked them, he'd have died at 75. (Bert Sugar, quoted in New York Times, September 20, 2002) Times, Based on your reading of this chapter, what fallacy does the arguer commit? What's to say against [cigars]? They killed George Burns at 100. If he hadn't smoked them, he'd have died at 75. (Bert Sugar, quoted in New York Times, September 20, 2002) Questionable cause. Given the proven health risks of cigar smoking, it is unlikely that cigar smoking caused George Burns to live to be 100. According to North Korea's official state-run news agency, "a war between North Korea and the United States will end with the delightful victory of North Korea, a newly emerging military power, in 100 hours. . . . The U. S. [will] be enveloped in flames. . . and the arrogant empire of the devil will breathe its last". Given that this prediction comes from the official North Korean news agency, it is probably true. (Passage quoted in Nicholas D. Kristof, "Empire of the Devil," New York Times, April 4, 2003) Based on your reading of this chapter, what fallacy does the arguer commit? According to North Korea's official state-run news agency, "a war between North Korea and the United States will end with the delightful victory of North Korea, a newly emerging military power, in 100 hours. . . . The U. S. [will] be enveloped in flames. . . and the arrogant empire of the devil will breathe its last". Given that this prediction comes from the official North Korean news agency, it is probably true. (Passage quoted in Nicholas D. Kristof, "Empire of the Devil," New York Times, April 4, 2003) New Inappropriate appeal to authority. The North Korean news agency's claim is implausible on its face. Moreover, as a state-run news organization in a totalitarian regime, the agency is simply a mouthpiece of the government, and hence is biased. Jurors in tobacco lawsuits should award judgments so large that they put tobacco companies out of business. Respecting the right of tobacco companies to stay in business is akin to saying there are "two sides" to slavery or the Holocaust. (Anti-tobacco lawyer, quoted in George F. Will, "Court Ruling Expresses Anti-Smoking Hypocrisy," Wilkes-Barre Times Leader, May 25, 2003) Times Based on your reading of this chapter, what fallacy does the arguer commit? Jurors in tobacco lawsuits should award judgments so large that they put tobacco companies out of business. Respecting the right of tobacco companies to stay in business is akin to saying there are "two sides" to slavery or the Holocaust. (Anti-tobacco lawyer, quoted in George F. Will, "Court Ruling Expresses Anti-Smoking Hypocrisy," Wilkes-Barre Times Leader, May 25, 2003) Times Weak analogy. Clearly there are major disanalogies between the tobacco industry and either slavery or the Holocaust. To cite just three obvious differences: (1) smoking is something that many people enjoy, (2) no one is forced to smoke, and (3) making all due allowances for the effects of second-hand smoke, smoking primarily affects only the health of the smoker, not innocent third parties. Bob: Affirmative action isn't "reverse discrimination." It isn't Bob: discrimination at all. Discrimination is adverse treatment based on an assumption of a group's inferiority, and no one claims that white males are inferior. claims Peg: But what about sexual harassment? You admitted earlier that sexual harassment is discrimination, but sexual harassment doesn't always involve an assumption of inferiority. inferiority. Bob: Granted, but sexual harassment is still discrimination because it denies equal opportunity in employment. because Based on your reading of this chapter, what fallacy does Bob commit? Bob: Affirmative action isn't "reverse discrimination." It isn't Bob: discrimination at all. Discrimination is adverse treatment based on an assumption of a group's inferiority, and no one claims that white males are inferior. claims Peg: But what about sexual harassment? You admitted earlier that sexual harassment is discrimination, but sexual harassment doesn't always involve an assumption of inferiority. inferiority. Bob: Granted, but sexual harassment is still discrimination because it denies equal opportunity in employment. because Inconsistency. Bob offers two different—and incompatible—definitions of Bob "discrimination." "discrimination." It will be tragic if this country ever legalizes gay marriage. Mark my words, once that happens, it won't be long until polygamy and incest are legal. polygamy Based on your reading of this chapter, what fallacy does this arguer commit this It will be tragic if this country ever legalizes gay marriage. Mark my words, once that happens, it won't be long until polygamy and incest are legal. polygamy Slippery slope. Although claims of this sort are often made, the feared consequences strike us as unlikely. The risks of individual and societal harm are much greater with polygamy and incest than they are with gay marriage, and the societal taboos are considerably stronger. [This is the end of the tutorial] [This X ...
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