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思辨精英：英语辩论-构筑全球视角 [:1705132479]
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16.1 Categories of Evidence
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As the foundation of argument, evidence consists of two categories: those relating to reality and those relating to preference. Evidence relating to reality is about how things “really” are, whereas evidence related to preference is about how people would like things to be. Evidence relating to reality includes facts, theories, and presumptions. A fact is, as the name implies, an individual bit of data. Theories go beyond individual facts and offer explanations or predictions. Presumptions describe expectations about people or events. Evidence relating to preference includes values, hierarchies, and categories of what people find to be preferable. Values are statements showing preference for some concept. Hierarchies order values, and categories of values are classifications of values that frequently are called upon to support an argument. Those categories are briefly described in the following table:
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思辨精英：英语辩论-构筑全球视角 [:1705132480]
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16.1.1 Evidence Based on Reality
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As stated above, evidence based on reality consists of the kinds of information relating to how things “really” are. Evidence based on reality can consist of facts, theories, and presumptions, among other things.
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16.1.1.1 Facts Facts include observed or potentially observable data. Sometimes, the arguer directly observes facts, but in many cases, facts are reported to the arguer through a third party such as a professor, a journalist, or someone else who directly observed the fact. At other times, factual evidence may consist of a previously supported claim of description or definition, as noted in the previous chapter. Facts include things that people may come across during the course of their professional or day-to-day lives. For example, arguers may find facts during day-to-day reading, observations made during classes, or reading specifically for preparation in debate. Debaters taking classes in history, sociology, or politics will learn all sorts of facts that they can use in debates. Debaters can also collect facts from reading a daily newspaper, a weekly news magazine, or various kinds of journals.
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Different kinds of factual evidence are useful to support claims and motions. Some of those include direct observations, historical descriptions, examples and illustrations, statistics, and descriptions of empirical studies. Of course, this list does not begin to exhaust the kinds of facts available to debaters.
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A. Direct observation is a very clear example of a fact and is often useful as evidence. Sometimes these kinds of facts are observed directly by the debater and sometimes they are reported from a third party. For instance, the observation that both giant and red pandas can be seen at the Chengdu Research Base of Giant Panda Breeding might be an observation made directly by a debater or it might be found using the Internet or library resources. In either case, this information constitutes a fact that might be used as partial support for an argument about the importance of protecting both kinds of pandas.
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B. Historical descriptions present the details of past events to support arguments. Using historical evidence, debaters may lay out sequences of historical events to show how those events support their arguments. For instance, debaters wishing to make a claim that “by all rights, the Diaoyu Islands are a part of the People’s Republic of China” might point to an historical description. For instance, they might suggest that those islands were repeatedly referred to as a part of Chinese territory since the Ming Dynasty. The relationship between the historical evidence and the subsequent claim might be diagramed as follows:
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In that instance, the historical evidence provides support for the claim about the PRC’s legitimate entitlement to the disputed islands.
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C. Examples and illustrations include specific instances that can support an argument. Using a series of examples to prove a general rule is called an argument by example. In most cases, people may not have access to every single specific case that would lend support to their claim. The argument by example seeks to provide support for a generalization. A generalization is a statement suggesting that the pattern visible in specific cases presented will also be visible in cases not presented. Thus, a generalization does not provide absolute proof of the claim; it merely makes a claim that is based on the presented examples.
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For example, persons claiming that International Studies is an appropriate major for students seeking careers in the Foreign Service do not base that claim on an examination of every single International Studies major to whom they refer. If they had such access, the question could be answered directly without the need to create an argument. Instead, an advocate may present several examples of International Studies majors who happen to be members of the Foreign Service, and then use those examples to support the claim that International Studies (IS) is an appropriate major for students seeking a career in the Foreign Service. Such an argument by example is illustrated in the following diagram:
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Part of the persuasiveness of an argument by example is dependent on the number of examples provided and on the representativeness of those examples. For instance, a generalization based on very few examples may be just as unreliable as a generalization based on examples that are not representative. Thus, an arguer is well advised to present as many examples as he or she can, given the constraints of time, and to make sure that the examples presented are representative of the population about which he or she wants to generalize.
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Having provided examples to support an argument, a debater can then make the argument even more persuasive by providing a vivid illustration. Illustrations function differently than examples. Although illustrations alone may not speak to the certainty of an argument, they make an argument more vivid. Continuing with the last hypothetical situation, the debater might find a particularly well-known member of the Foreign Service who also was an International Studies major and use that story to make the claim more vivid. As a slightly different example, consider the claim that participation in debate is common for exceptional lawyers. An illustration might be thought of as a brief story to give added weight to the generalization. A debater might support this claim by finding several examples of exceptional lawyers who were also debaters, and then focusing on a specific person who has a background in both law and debate. For instance, a debater might present a brief story about Laurence H. Tribe, who was born in China to Russian-Jewish parents. He was the United States national debate champion in 1960, and has gone on to become the preeminent constitutional law authority in the United States, winning over 35 cases before the United States Supreme Court.
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An illustration may not provide logical support to an argument, because a single example does not provide sufficient support to make a generalization from one example to a general rule.6 An illustration enables the audience to “visualize” the point that the debater is making and, as a result, the claim becomes more vivid. Thus, examples and illustrations are complementary kinds of evidence: Sufficient and representative examples lend logical support to an argument and illustrations make the claim more vivid and persuasive.
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D. Statistics are useful when a debater wants to make a generalization about some group of people or things. As in the case of argument by example, the debater does not have information about every individual in the group. A statistic starts with a description of a sample of the group, which allows the arguer to state that the sample probably is like the group as a whole. For instance, if 80% of the members of a debate team at a particular university are English majors, the inference could be drawn (rightly or wrongly) that 80% of all collegiate debaters are English majors. In some cases, a statistic can be a persuasive form of factual evidence. Statistics, used properly, are especially powerful evidence in the hands of a skilled debater.
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Any form of evidence can be misleading, and statistics are no exception. Debaters need to be wary about statistics and examine them closely to make sure that the claim supported by the statistics is a good one. For instance, statistics show that women taking hormone replacement therapy have a lower-than-average incidence of coronary heart disease. One interpretation of this statistic is that hormone replacement therapy protects women against coronary heart disease.
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However, a closer look at the data on which the statistic is based also shows that women who received hormone replacement theory were more likely to be from higher socio-economic groups with better-than-average diet and exercise regimens. Thus, the statistic supporting a relationship between hormone replacement therapy and coronary heart disease may be confounded by socioeconomic status of the women in the statistical sample (Lawlor, Smith, and Ebrahim 2004: 464-467). This is just one example where statistics can be misinterpreted. The main point is that statistics do not interpret themselves. People interpret statistics and need to be careful to provide accurate and complete interpretations.
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E. Descriptions of empirical studies generally include statistics associated with a number of variables. Empirical studies are sometimes more persuasive than “raw statistics” because they are based on underlying theoretical explanations as well as on figures.
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For instance, Shijie Yang collected statistics about the effect of hukou reforms on the income gap between rural and urban workers. Collecting data in five provinces between 1999 and 2005, Shijie Yang found that the hukou reforms in those provinces had the opposite of the intended effect. The study concluded that the hukou reforms “actually caused the income gap between urban and rural citizens to become wider, instead of narrower.”