【Big Fish】3月3日Argument150-By rachelwang712

rachelwang712UID: 2757860

3.03 Argument No.150

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."

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提纲：
1没有足够的调查来显示trout的数量，如果它在现在很多，那么有可能是从吃egg来繁衍的
2公园的水和空气是否污染没有涉及，
3而且公园与世界各地的environment是不一样的

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The letter, though clearly-presented, is weak in its reasoning. The author's failure to provide adequate information concerning the amount of trout over the period, the seriousness of air and water pollution both in park and worldwide and the feasibility to draw any comparison between Yosemite and the world undermines his cogency.

To begin with, information mentined about trout is too general to forcefully imply whether they are the sculpit for the sharp decline in amphibians or not. To be exact, there will be two totally different stories whether trout were annihilated shortly after introduction or they prospered by eating in greed legions of amphibian eggs. Thanks to that, neither readers nor the writer can claim firmly the relationship between trout and fall in amphibians.

Moreover, the author also fails to mention specifically level of air and water pollution and changes over the reported period both in Yosemite and worldwide. As the author is trying to owe decrease in the number of amphibians to air and water pollution, it is recommended that he adds in more information indicating level of these. It is probable that in Yosemite, while amphibians are fewer and fewer, the environment remains the same or even gets better. If such case exists, it is inevitable that the letter is doubtable for its poor credibility.

Finally, even the case in Yosemite affirms the arguer's assumption, it does not necessarily mean that environment degration is the only reason for declining amphibians in the whole world. I sincerely worry that the author has been rushing to conclusion by drawing a careless, if not random, comparison between Yosemite and other habitats for amphibians. To put it in another way, more researches are needed to look deeply into similarities and differences. Maybe that amphibians in Asia are diving in number largely due to deforestation or shortage of food rather than water and air pollution held by the arguer. So the arguer's point rarely stands.

In conclusion, readers of the letter should be mindful of the imprudent argumentation it contains. To polish the reasoning and make the letter more eloquent, the arguer needs to include necessary information to answer possible questions listed above. Only in that way can he finally manage to convince people of the severity of harms done by water and air pollution and appeal them to take action to address the problem.