批判性思维 (8).pdf

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1、 What is the most common(and most seductive)error in reasoning on the planet?You are about to fi nd out.In this chapter,we examine the infamous argu-mentum ad hominem,as well as other common fallacies.To remind you of the overall picture,in Chapter 5 we explored ways the rhetorical content of words

2、and phrases can be used to affect belief and attitude.In Chapter 6,we considered emotional appeals and related fallacies.The fallacies we turn to now,like the devices in the preceding chapters,can tempt us to believe something without giving us a legitimate reason for doing so.THE AD HOMINEM FALLACY

3、 The ad hominem fallacy(argumentum ad hominem)is the most common of all mistakes in reasoning.The fallacy rests on a confusion between the qualities of the person making a claim and the qualities of the claim itself.(“Claim”is to be understood broadly here,as including beliefs,opinions,positions,arg

4、uments,proposals and so forth.)Parker is an ingenious fellow.It follows that Parker s opinion on some subject,whatever it is,is the opinion of an ingenious person.But it does not follow that Parker s opinion itself is ingenious.To think that it is would be to Students will learn to.1.Recognize sever

5、al types of fallacies that confuse the qualities of a person making a claim with the qualities of the claim2.Recognize the fallacy involved in thinking that a claim is refuted because of its origin3.Recognize fallacies that misrepre-sent an opponents position4.Recognize fallacies that errone-ously l

6、imit considerations to only two options5.Recognize fallacious claims that one action or event will inevitabil-ity lead to another6.Recognize arguments that place the burden of proof on the wrong party7.Recognize the problem in argu-ments that rely on a claim that is itself at issue 7 More Fallacies

7、210 moo38286_ch07_210-252.indd 210moo38286_ch07_210-252.indd 21012/9/10 2:59 PM12/9/10 2:59 PM THE AD HOMINEM FALLACY 211confuse the content of Parker s claim with Parker himself.Or let s suppose you are listening to somebody,your teacher perhaps,whom you regard as a bit strange or maybe even weird.

8、Would it follow that the car your teacher drives is strange or weird?Obviously not.Likewise,it would not follow that some specifi c proposal that the teacher has put forth is strange or weird.A proposal made by an oddball is an oddball s proposal,but it does not follow that it is an oddball proposal

9、.We must not confuse the qualities of the person making a claim with the qualities of the claim itself.We commit the ad hominem fallacy when we think that considerations about a person“refute”his or her assertions.Ad hominem is Latin for“to the man,”indicating that it is not really the subject matte

10、r that s being addressed,but the person.The most common varieties of the ad hominem fallacy are as follows.The Personal Attack Ad Hominem “Johnson has such-and-such a negative feature;therefore,his claim(belief,opinion,theory,proposal,etc.)stands refuted.”This is the formula for the personal attack

11、ad hominem fallacy.The name“personal attack”is self-explanatory,because attributing a negative feature to Johnson is attacking him personally.Now,there are many negative features that we might attribute to a per-son:Perhaps Johnson is said to be ignorant or stupid.Maybe he is charged with being self

12、-serving or feathering his own nest.Perhaps he is accused of being a racist or a sexist or a fascist or a cheat or of being cruel or uncaring or soft on communism or taking pleasure in strangling songbirds.The point to remem-ber is that shortcomings in a person are not equivalent to shortcomings in

13、that person s ideas,proposals,theories,opinions,claims,or arguments.This is not inconsistent with what was said about credibility.Indeed,facts about the source of a claim can correctly make us skeptical about the claim.But we should not ordinarily conclude that it is false on this account.Now,it is

14、true that there are exceptional circumstances we can imagine in which some feature of a person might logically imply that what that person says is false;but these circumstances tend to be far-fetched.“Johnson s claim is false because he has been paid to lie about the matter”might qualify as an examp

15、le.“Johnson s claim is false because he has been given a drug that makes him say only false things”would qualify,too.But such situations are rare.True,when we have doubts about the credibility of a source,we must be careful before we accept a claim from that source.But the doubts are rarely sufficie

16、nt grounds for outright rejection of the claim.No matter what claim Johnson might make and no matter what his faults might be,we are rarely jus-tifi ed in rejecting the claim as false simply because he has those faults.The Inconsistency Ad Hominem “Moores claim is inconsistent with something else Mo

17、ore has said or done;therefore,his claim(belief,opinion,theory,proposal,etc.)stands refuted.”This is the formula for the inconsistency ad hominem,and you encounter versions of this fallacy all the time.An example:In 2008 Hillary Clinton and Barack Obama were both vying for the Democratic nomination

18、for the presi-dency.After Obama was quoted as saying he had“no intention of taking away They believe the Boy Scouts position on homosexuality was objectionable,but they gave no heed to peoples objections about using state money to fund displays about sodomy in the peoples Capitol.California assembly

19、man BILL LEONARD(R-San Bernardino),criticizing the legislature for funding a gay pride display in the states CapitolMan!As if sodomy in the peoples Capitol isnt bad enough,they have to go and fund displays about it!Leonards remark is an example of an inconsistency ad hominem.(It also contains a wild

20、 syntactical ambiguity,as noted above.)moo38286_ch07_210-252.indd 211moo38286_ch07_210-252.indd 21112/9/10 2:59 PM12/9/10 2:59 PM212 CHAPTER 7:MORE FALLACIESfolks guns,”the Clinton campaign pointed out that on a 1996 questionnaire Obama had said he“supported banning the manufacture,sale and possessi

21、on of handguns,”and that this showed that his new claim about not intending to“take away folks guns”was not really true.Again,the fact that one opinion was expressed in 1996 and a different one in 2008 is not grounds for rejecting the latter as false.Although accusations of doing a“fl ip-fl op”are s

22、tandard in political campaigns,it s important to look beneath the surface to see how dif-ferent the two positions really are and whether there might be a good reason for changing one s mind.The fact that people change their minds has no bear-ing on the truth of what they say either before or after.I

23、n DepthAd HominemThe idea behind the ad hominem fallacy is to point to the person making a claim and accuse him or her of some flaw,evil deed,or other negative feature.By indicting the person behind the claim,the accuser hopes to refute the claim.But while some fact about the author of a claim may a

24、ffect his or her credibility,it cannot by itself demonstrate that the claim is false.moo38286_ch07_210-252.indd 212moo38286_ch07_210-252.indd 21212/9/10 2:59 PM12/9/10 2:59 PM THE AD HOMINEM FALLACY 213 Sometimes a person s claim seems inconsistent,not with previous state-ments but with that person

25、s behavior.For example,Johnson might tell us to be more generous,when we know Johnson himself is as stingy as can be.Well,Johnson may well be a hypocrite,but we would be guilty of the incon-sistency ad hominem fallacy if we regarded Johnson s stinginess or hypocrisy as grounds for rejecting what he

26、says.This type of reasoning,where we reject what somebody says because what he or she says seems inconsistent with what he or she does,even has a Latin name:tu quoque,meaning“you,too.”This version of the inconsistency ad hominem often boils down to nothing more than saying“You,too”or“You do it,too!”

27、If a smoker urges another smoker to give up the habit,the second smoker commits the inconsistency ad hominem if she says,“Well,you do it,too!”The Circumstantial Ad Hominem “Parkers circumstances are such and such;therefore,his claim(belief,opin-ion,theory,proposal,etc.)stands refuted.”This is the fo

28、rmula for the circum-stantial ad hominem.An example would be“Well,you can forget about what Father Hennesy says about the dangers of abortion,because Father Hennesy s a priest,and priests are required to hold such views.”The speaker in this exam-ple is citing Father Hennesy s circumstances(being a p

29、riest)to“refute”Father Hennesy s opinion.This example isn t a personal attack ad hominem because the speaker may think very highly of priests in general and of Father Hennesy in particular.Clearly,though,a person could intend to issue a personal attack by mentioning circumstances that(in the opinion

30、 of the speaker)constituted a defect on the part of the person attacked.For example,consider“You can forget about what Father Hennesy says about the dangers of abortion because he is a priest and priests all have sexual hang-ups.”That would qualify as both a circumstantial ad hominem(he s a priest)a

31、nd a personal attack ad hominem(priests have sexual hang-ups).Poisoning the Well Poisoning the well can be thought of as an ad hominem in advance.If someone dumps poison down your well,you don t drink from it.Similarly,when A poi-sons your mind about B by relating unfavorable information about B,you

32、 may be inclined to reject what B says to you.Well-poisoning is easier to arrange than you might think.You might sup-pose that to poison someone s thinking about Mrs.Jones,you would have to say or at least insinuate something deprecatory or derogatory about her.In fact,recent psycholinguistic resear

33、ch suggests you can poison someone s thinking about Mrs.Jones by doing just the opposite!If we don t know Mrs.Jones,even a sentence that expresses an outright denial of a connection between her and something unsavory is apt to make us form an unfavorable impression of her.Psychological studies indic

34、ate that people are more apt to form an unfavorable impression of Mrs.Jones from a sentence like“Mrs.Jones is not an ax mur-derer”than from a sentence like“Mrs.Jones has a sister.”Moral:Because it might be easy for others to arrange for us to have a negative impression of someone,we must be extra ca

35、reful not to reject what a person says just because we have an unfavorable impression of the individual.I get calls from nutso environ-mentalists who are filled with compassion for every snail darter that is threatened by some dam somewhere.Yet,they have no interest in the 1.5 million fetuses that a

36、re aborted every year in the United States.I love to argue with them and challenge their double standard.RUSH LIMBAUGHOften an inconsistency ad hominem will accuse someone of having a double standard.Notice how this example is combined with ridicule(See Chapter 5).Hey,maybe you have no better sense,

37、but I personally would not accept anything as news coming from that fat drug-addicted loudmouth.-Comment on a media blogAn ad hominem used against Limbaugh.moo38286_ch07_210-252.indd 213moo38286_ch07_210-252.indd 21312/9/10 2:59 PM12/9/10 2:59 PM214 CHAPTER 7:MORE FALLACIES “Positive Ad Hominem Fall

38、acies”An ad hominem fallacy,then,is committed if we rebut a person on the basis of considerations that,logically,apply to the person rather than to his or her claims.Strictly speaking,if we automatically transfer the positive or favorable attributes of a person to what he or she says,that s a mistak

39、e in reasoning,as well.The fact that you think Moore is clever does not logically entitle you to conclude that any specifi c opinion of Moore s is clever.The fact that,in your view,the NRA represents all that is good and proper does not enable you to infer that any specifi c proposal from the NRA is

40、 good and proper.Logicians did not always limit the ad hominem fallacy to cases of rebuttal,but that seems to be the usage now,and we shall follow that policy in this book.You should just remember that a parallel mistake in reasoning happens if you confuse the favorable qualities of a person with th

41、e qualities of his or her assertion.THE GENETIC FALLACY The genetic fallacy occurs when we try to“refute”a claim(or urge others to do so)on the basis of its origin or its history.If this sounds like what we ve been talking about in the ad hominem section,it s no surprise.The genetic fal-lacy is ofte

42、n considered to be a blanket category for all fallacies that mistake an attack on a source for an attack on the claim in question.Taken this way,all versions of ad hominem,poisoning the well,and so forth,are also examples of the genetic fallacy.In our treatment,we reserve the use of the term“genetic

43、 fallacy”for cases where it isn t a person that is disparaged as the source of a claim but some other kind of entitya club,a political party,an industrial group,or even an entire epoch.An example of the latter would be attempting to refute a belief in God because that belief fi rst rose in superstit

44、ious times when we had few natural explanations for events like storms,earthquakes,and so on.We have heard people declare the U.S.Constitution“invalid”because it was(allegedly)drafted to protect the interests of property owners.This is another example of the genetic fallacy.If we“refute”a proposal(o

45、r urge someone else to reject it)on the grounds that it was part of the Republican(or Democratic)party platform,we commit the genetic fallacy.If we“refute”a policy(or try to get others to reject it)on the grounds that a slave-holding state in the nineteenth century originated the policy,that qualifi

46、 es.If we“rebut”(or urge others to reject)a ballot initiative on the grounds that the insurance industry or the association of trial law-yers or the American Civil Liberties Union or“Big Tobacco”or“Big Oil”or multinational corporations or the National Education Association or the National Rifl e Ass

47、ociation or the National Organization for Women proposed it or back it,we commit the fallacy.Knowing that the NRA or the NEA or NOW proposed or backs or endorses a piece of legislation may give one reason(depending on one s politics)to be suspicious of it or to have a careful look at it;but a percei

48、ved lack of merit on the part of the organization that proposed or backs or endorses a proposal is not equivalent to a lack of merit in the pro-posal itself.Knowing the NRA is behind a particular ballot initiative is not the same as knowing about a specifi c defect in the initiative itself,even if y

49、ou detest the NRA.Whom are they kidding?Where are NOWs constitutional objec-tions to the billions of dollars(including about$1 million to NOW itself)that womens groups receive under the Vio-lence Against Women Act?ARMIN BROTT,issuing an ad hominem response to opposi-tion by the National Organiza-tio

50、n for Women to a proposal to provide poor fathers with parenting and marital-skills training and classes on money managementGender-based inconsistency ad hominemmoo38286_ch07_210-252.indd 214moo38286_ch07_210-252.indd 21412/9/10 2:59 PM12/9/10 2:59 PM THE GENETIC FALLACY 215 Classify each of the fol