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21.2.3.2 Slippery Slope Arguments Slippery Slope arguments sometimes are fallacious. Using such arguments, debaters try to connect a series of events in a causal chain that ultimately “culminate[s] in calamity” (Govier, 2009: 439).
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Contrary to popular opinion, slippery slope arguments are not necessarily fallacies (Volokh and Newman 2003: 21-23). They only are fallacies when all of the connections in the causal chain are not properly made. Even though the connections are relevant to the claim, they may be fallacious because the connections are insufficiently documented.
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Americans who oppose restrictions on gun ownership commonly argue that one form of control will lead to another, which will eventually lead to the prohibition of all guns, including hunting rifles. The argument is that, “If we allow restrictions on the ownership of semiautomatic firearms, then anti-gun politicians feeling their political muscles will see handgun ownership as their next target. If they succeed in banning the ownership of handguns, it will be a short time until they are able to build political momentum to outlaw all kinds of firearms including hunting rifles as well as gun collections.” The argument as presented above is a slippery slope fallacy because the causal connections between each of the steps are not well documented.
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The arguments described above are fallacious because, even though they may be relevant to the claims they are making, their premises or evidence are insufficient to establish the claims. A large number of other fallacies also can be included in the category of hasty conclusions. Some of those are briefly described below.
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21.2.3.3 Two Wrongs Two wrongs is a label used for a fallacy commonly called “Two wrongs don’t make a right.” As “a misplaced appeal to consistency. A person is urged to accept or condone one thing that is wrong because another similar thing, also wrong, has occurred or has been accepted and condoned” (Govier, 2009: 444).
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21.2.3.4 Improper Appeal to Practice It is a fallacy that assumes that a person is justified in doing things that are common practice, even if that practice is clearly wrong. “Why should I pay the women in my business wages equal to men? Other businesses pay men more, so I should be able to do the same.”
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21.2.3.5 Fallacy of Composition It is a fallacy in which the evidence is drawn from some part of a whole, but the conclusion is about the whole (Govier, 2009: 439). “He Jingkai, a debater from China, is a superb debater. Therefore, China has some of the best debaters in the world.” China may well have excellent debaters, but this argument, nevertheless, makes a fallacious statement about the relationship of the part (He Jingkai) to the whole (Chinese debaters).
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21.2.3.6 Fallacy of Division It involves a fallacious argument in which the evidence is drawn from the whole, but the conclusion is about a part of the whole. The argument assumes that what is true of the whole must be true of its constituent parts. “Harvard is an excellent university, therefore Lawrence Tribe, who is a law professor at Harvard, must be an excellent professor.” Like the above example, the claim may be correct, but the reasoning is fallacious because it makes an improper statement about the relationship between the whole (Harvard) and its constituent parts (Professor Tribe).
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21.2.3.7 Post Hoc Fallacy It is also called by its Latin name post hoc, ergo propter hoc, which means “after this, therefore before this.” This fallacious argument assumes that, because one thing predates another, the first must have caused the second. A person may argue that “After Barak Obama took office, the US economy went into a recession; thus, Obama’s policies were the cause of the recession.” Whether Obama’s policies contributed to the recession has not been argued well here. The debater has simply assumed a cause-and-effect relationship.
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21.2.3.8 Faulty Analogy It is a fallacy that occurs when two cases are compared to each other but are not similar in terms of the relationship stated in the comparison. Were someone to argue that Nelson Mandela is today’s Abraham Lincoln, that argument would be subject to the charge of faulty analogy. Whether or not that charge is correct would depend on whether or not the argument presented sufficient similarities between Mandela and Lincoln, and on whether or not Mandela and Lincoln were different in significant ways.
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The fallacies in the preceding section are related to the standard of sufficiency. In prior sections we described fallacies related to each of the standards of a quality argument: acceptability, relevance, and sufficiency. This list of fallacies certainly is not exhaustive.
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思辨精英：英语辩论-构筑全球视角 [:1705132539]
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21.3 Summary
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Several of the previous chapters in this text have described the kinds of arguments, the elements that comprise them, and the various structures into which arguments are crafted. This chapter changed directions to discuss the quality of arguments—those features that separate better arguments from worse arguments. The three criteria discussed were acceptability of evidence, relevance, and sufficiency of the link between evidence and claim. Along with those three criteria, the chapter discussed the most basic of fallacies that correspond to each of the three criteria: problematic premises, irrelevant reasons, and hasty conclusions. Then, each of those categories was exemplified by more specific fallacies classified under each.
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This chapter also emphasized that fallacies are not the only criteria relevant to argument quality. Fallacies only relate to the logical dimension of argument. Even then, the presence of a fallacy does not mean an argument is not cogent or persuasive—only that it could be made more cogent and persuasive by removing the fallacy. Similarly, the absence of a fallacy does not mean the argument is persuasive—only that an argument without fallacies is more persuasive and cogent. As such, fallacies are as much a call for debaters to improve their arguments as they are a call for judges and audiences to reject the arguments.
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在之前的几章中，我们介绍了论证的种类、要素及其结构。本章则将重点放在了论证的质量上，介绍了区分好坏论证的特质。文中提到的三个评判标准是——论据的接受度、论点及论据间关联的相关度和充分度。除了这三个评价标准之外，本章也介绍了与这三种标准相对应的三种最基本的谬误——前提错误类谬误、相关性谬误以及充分性谬误。其中，每个种类下又列举了一些具体的谬误加以举例说明。
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此外，本章还强调，谬误并不是论证质量唯一的评价标准，它仅仅与论证逻辑这一衡量维度相关。存在谬误并不代表这个论证不具有说服力，这只是表示，如果去除了其中的谬误部分，它会更加令人信服。同样的，论证中不存在推理谬误也并不意味着这个论证具有说服力，只能表示这个论证因为没有推理谬误而相对更令人信服。综上所述，是否存在推理谬论不仅是辩手是否需要提高论证质量的重要依据，也是评委和观众判断是否能够接受论证的重要依据。
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思辨精英：英语辩论-构筑全球视角 [:1705132540]
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21.4 Terms and Concepts from Chapter 21
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Check your memory and comprehension by describing or defining these key terms and concepts:
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· Johnson and Blair Model of Argument Cogency
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· Acceptability
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· Relevance
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· Sufficiency
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· Problematic premises