argument150 互拍留链接

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150The 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."

In the letter, the arguer regards that the decline in the numbers of amphibian worldwide is global pollution of water and air rather than introduction of trout cannot be the real reason for the Yosemite decline since it fails to explain the worldwide decline. To bolster it, the arguer cites that in 1915 there were seven species, while in 1992 there were only four species of amphibians just because of the introduction of trout that are known to eat amphibian eggs since 1920. However, in my views, the conclusion is unpersuasive as it stands and some fallacies hidden in the argument will be disclosed after a close example and scrutiny as follows.

In the first place, the arguer cites the two studies of amphibians in Yosemite National Park. However, the arguer fails to provide detailed information about studies involving whether the study is authority or not, whether the sample is enough to substantiate the whole circumstance, and whether only the decline of amphibians rather than other species can explain the reason that it is global pollution of water and air, etc. Consequently, without aforementioned information above, the reliability of the studies is deserved to doubt. If the studies are untrue, then the conclusion is questioned.

In the second place, even if the studies is true, it is not guaranteed that the decline of Yosemite does not result from the introduction but the global pollution of water and air, while the real reason is just the trout. Perhaps the trouts destroy the biologic links of nature and ecology circumstance. A number of trout are conceived and in turn eat up the amphibian eggs and bring out the overcome of nature unbalance. In a word, the arguer fails to provide evidence to rule out the reason that causes the decline in the number of amphibians.

Finally, the arguer commits a plausible mistake that he or she fails to rule out other possibilities that may cause the decline of the numbers of amphibians. Maybe besides the introduction of trout, still there are other species that can also destroy the amphibian eggs. It is possible that extensive and high temperature on the ground just because of drought and long-term hot days killed the amphibians’ eggs. Consequently, unless the arguer rules out other possibilities, the conclusion can be weakened remarkably.

In sum up, based on what has discussed above, it is clear that the conclusion in the argument is invalid. In order to make it more bilievable, the arguer should provide more information about the studies, the facts to justify that trout is not the culprit to cause the decline of amphibians, as well as ruling out other possibilities that can bring out the overcome.