Arg-54
Humans arrived in the Kaliko Islands about 7,000 years ago. Within 3,000 years, most of the large mammal species that had lived in the forests of the Kaliko Islands had become extinct. Humans, however, could not have been a factor in the species' extinction because there is no evidence that the humans had any significant contact with the mammals. Further, archaeologists have discovered numerous sites where the bones of fish had been discarded, but they found no such areas containing the bones of large mammals. Climate change or other environmental factor must have caused the species' extinctions.
Write a response in which you examine the stated and/or unstated assumptions of the argument. Be sure to explain how the argument depends on these assumptions and what the implications are for the argument if the assumptions prove unwarranted.
In this argument the speaker concludes that humans could not have caused the extinction of large mammal species in the Kaliko islands. To justify this conclusion, the speaker points out that no evidence exists that humans hunted or had contact with these mammals. The speaker also indicates that while archeologists have found bones of discarded fish in the islands, they have not found any discarded mammal bones there. There are three reasons why this argument isn’t persuasive.
【此段结构】
本段采用了标准的Argument开头段结构，即：C – E - F的开头结构，首句概括原文的C(Conclusion)。接下来的一句话概括了原文为了支持他的结论所引用的E(Evidence)。最后尾句中给出开头段到正文段的过渡句，指出原文在逻辑上存在F(Flaw)。
【此段功能】
本段作为Argument开头段，具体功能就在发起攻击。首先，概括原文的结论：人类不可能引起Kaliko(简称K)岛上大型哺乳动物的灭绝。接下来分别列举了原文为了支持这个结论引用的证据：一是没有关于人类猎杀或接触这些动物的证据，二是考古学家发现丢弃的鱼骨但没有发现丢弃的mammal的骨头。论据的归纳用于铺垫出正文段的具体攻击。最后点出原文存在逻辑错误，引出后面的分析。
First, the argument concludes that humans did not have had any significant contact with the mammals based on the fact that no physical evidence exists to indicate as much. The author overlooks the possibility that humans exported mammals during this time period or had some other contact that caused the extinction. Perhaps the humans took over sources of food or critical habitats, which allowed the animals to service. Without ruling out alternative explanations, the speaker cannot Support the conclusion of the argument.
【此段结构】
本段采用了标准的Argument正文段结构，即：概括第一个逻辑错误的错误类型和原文犯错位置，接下来给出合理的理由和他因来反驳原文。
【此段功能】
本段作为正文第一段，攻击文章犯的主要逻辑错误：因果类错误(忽略他因)。原文中虽然提到没有发现人类猎杀和接触的证据，但作者人为原文忽略了人类对mammal其他方面的影响。进一步，作者提出其他的可能性来证实自己的观点。例如，人类可能抢占了mammal的food或者critical habitat。如果没有排除这些可能的因素，就不能得出原文中的论断。
Secondly, the argument relies on the assumption that without significant contact with these other species humans could not have been a factor in their extinction but the speaker provides no evidence. Perhaps humans drove these other species away from their natural habitat by intruding on their territory. Perhaps humans consumed the plants and animals on which these species relied for their subsistence. Either scenario would explain how humans could have been a factor in the extinction of these species despite a lack of significant contact.
【此段结构】
本段采用了标准的Argument正文段结构，即：概括第二个逻辑错误的错误类型和原文犯错位置，接下来给出合理的理由和他因来反驳原文。
【此段功能】
本段作为正文第二段，攻击文章犯的主要逻辑错误：错误因果(忽略他因)。原文中认为人不可能造成mammal灭绝因为没有significant contact。作者认为，原文在这方面缺乏证据。进一步，作者提出其他人类造成mammal灭绝的可能性，例如人类占据了mammal的栖息地，或者人类消耗了mammal吃的动物或植物。
Thirdly, the speaker assumes that the bones of fish that archeologists have found discarded on the island were discarded by humans, and not by some other large mammal. However, the speaker provides no evidence to substantiate this assumption. Perhaps the source of fish ran out and the animals died. Maybe the animals ingested a seaborne poison and entered it into the food chain. Given other possible explanations this evidence lends little credible support to the speaker's theory about the extinction of large species of mammals.
【此段结构】
本段采用了标准的Argument正文段结构，即：概括第三个逻辑错误的错误类型和原文犯错位置，接下来给出合理的理由和他因来反驳原文。
【此段功能】
本段作为正文第三段，攻击文章犯的主要逻辑错误：错误因果(论据模糊)。原文中提到发现discarded fish bone没有发现discarded mammal bone，作者认为这不足以说明mammal的灭绝不是认为因素引起的。进一步，作者给出了两种可能性来反驳原文的观点。一是mammal的灭绝可能是因为鱼被过于消耗，二是mammal可能吸收了海中的毒素并把这种毒素带到食物链中。
In conclusion, the argument is unconvincing. To strengthen it, the speaker must found all of the assumptions. For example, the speaker must rule out the possibility that humans exported the animals or bones. Or, perhaps, recognize that a lack of physical evidence doesn’t necessarily indicate the presence or absence of contact. To better evaluate the argument, the audience would need more information about the diet of humans and of the now-extinct mammals during that time period. Particularly, the audience would need to know whether those other mammals also fed on the fish whose discarded bones have been found on the islands.
【此段结构】
本段采用了标准的Argument结尾段结构，即：C – S的结尾结构，首先再次重申原文的站不住脚的Conclusion，接下来给出给合理建议Suggestion。
【此段功能】
本段作为Argument结尾段，具体功能就总结归纳+建议措施，首先再次重申原文的论断是没有说服力的。接下来作者给出几条建议：一是作者需要排除人类把mammal或它们的骨头带走的可能性，二是要知道当时人类和灭绝动物的饮食习惯，三是要知道灭绝的mammal是否以被发现骨头的鱼类为食。这几条建议含蓄的隐射前面的错误，前后呼应，文章有力结尾，浑然一体。
满分因素剖析
一、语言方面
1. First, the argument concludes that ... based on the fact that ... .(标志性的
2. In conclusion, the argument is unconvincing. (标志性的GRE argument结尾段开头句，再次重申原文中的结论存在逻辑错误)To strengthen it, the speaker must found all of the assumptions. For example, the speaker must rule out the possibility that... . Or, perhaps, .... . To better evaluate the argument, the audience would need more information about ... . Particularly, the audience would need to know whether ... .(给出使原文更加有说服力的四条合理化建议，其中前两条建议以the speaker为主语，后两条建议以the audience为主语，句式富于变化。)
二、逻辑结构
本文内容清晰，逻辑严谨，采用了开头段——正文段1——正文段2——正文段3—结尾段的五段论结构，文章长短适中，层次一目了然。开头段按照C-E-F的逻辑结构，顺利引出后文的分析。论证段中，从提出错误，到分析错误，到给出可能性，最后总结错误，层次清晰，衔接自然。结尾段总结全文，重申错误，给出合理化建议。这样一篇文章从开头到结尾逻辑严谨，内容清晰，圆满的完成了论证的作用。
