ARGUMENT150 - The following is a letter to the editor of an environmental magazine.
"The decline in the numbers of amphibians worldwide clearly indicates the global pollution of water and air. Two studies of amphibians in Yosemite National Park in California confirm my conclusion. In 1915 there were seven species of amphibians in the park, and there were abundant numbers of each species. However, in 1992 there were only four species of amphibians observed in the park, and the numbers of each species were drastically reduced. The decline in Yosemite has been blamed on the introduction of trout into the park's waters, which began in 1920 (trout are known to eat amphibian eggs). But the introduction of trout cannot be the real reason for the Yosemite decline because it does not explain the worldwide decline."
字数：390 用时：0:30:00 日期：2008-2-28
In this argument, the author claims that the global pollution of water and air is the reason for the decline in the numbers of amphibians worldwide.【个人觉得这个有点片面“The decline in the numbers of amphibians worldwide clearly indicates the global pollution of water and air." 应该是说两栖动物减少是全球污染的一个反映和结果，就是说把作者的另一层意思，两栖动物减少可以反映全球污染给丢了】 The author cites the results of two studies, and exclude another possible reasons to ensure us of its rationality. However, a close scrutiny of the supporting evidences reveals that this argument suffers from several flaws, which render it unpersuasive.
In the first place, the argument is based on the assumption that the numbers of amphibians are declining In the park. However, the author fails to provide any persuasive evidence. Though the author cites the results of two studies of amphibians in Yosemite National Park in California, the data of the two studies cannot serve to substantiate his/her assumption. The author does not provide us with any information about the process of the survey. So we cannot make it sure that whether the situation observed by the survey conductors can reflect the true situation of the park. It is quite possible that some of the amphibians in the park has changed their habitats, so the observers have not find them in 1922. Or perhaps the two study had used different method, so it is meaningless to compare the result of them. Any of these scenarios, if true, may serves to undermine the assumption.【两个假设注意了细节支持，很好】
In the second place, the argument is based on the assumption that the numbers of amphibians are declining world widely. However, the author fails to provide us with any information to prove it, such as statistic results of worldwide surveys or worldwide phenomenon 【可以用复数phenomena】which can reflect the trend. Even assuming that amphibians are declining in the park, the situation in a park cannot represent the situation worldwide. It is quite possible that the decline only happens in Yosemite National Park, and the numbers of amphibians in other places have note 【not】declined or even increased. If the author cannot exclude this possibility, he/she cannot make us to believe that the numbers of amphibians is declining world widely.
In the third place, by exclude 【excluding】the possibility that the decline of the amphibians is caused by the introduction of trout, the author implies that there is no other possibilities. However, there is no evidence to support this assertion. It is quite possible that though the introduction of amphibians 【trout】is not the reason, the declining of the numbers of amphibians is caused by other reasons, rather than pollution of water and air. For example, perhaps it is the excessive hunting 【细节】that has caused the decline. Or perhaps the rising global temperature 【细节】should be blamed. If the author cannot exclude these and other possibilities, he/she cannot persuasive us that the pollution is the reason.
In sum, the argument suffers from several flaws which render it logically unpersuasive as it stands. To strengthen the argument, further investigation and analysis should are needed. If so, it will be more thorough and adequate.
太感谢楼上的朋友了，那么认真的帮我改，那么中肯的意见，太感动了！
我觉得你说的很对，我对题目的理解是有偏差的，攻击的观点应该改成你所建议的那样。
另外，我觉得我第三段段中有攻击从‘一个典型样本推广到所有个性都是如此’这个错误，只不过我将它作为证据不充分来攻击了（Even assuming that amphibians are declining in the park, the situation in a park cannot represent the situation worldwide. It is quite possible that the decline only happens in Yosemite National Park, and the numbers of amphibians in other places have note 【not】declined or even increased.）是不是这样攻击不如将这个错误单独拎出来好？作者: hacker198679 时间: 2008-2-29 07:24:21 标题: 回复 #4 ustcroad 的帖子