argument150 多多指教

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TOPIC：ARGUMENT 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."
WORDS：444          TIME：0:45:31          DATE：2008-3-16

It was cited that the global pollution of water and air had caused amphibians decreasing. Before we had completely believed the fact, the writer should reconsider the conclusion with further scrutiny of those evidences mentioned in the letter. Plausible they may seem to support the conclusion, in fact, however, the author ignored some cases which would leave it open to doubt as below.
In the first place, the result of the two studies taken in Yosemite National Park(YNP) lend little credit to support the assumed decline situation. Perhaps the two researches took different calculating method: with the lack of identify technology, the former one may mistaken count the same amphibian twice, while the latter calculated precisely with the assistance of newly developed equipment. Or perhaps the size of field they made study in 1992 was quite smaller than that of 1915. As a consequence, number of amphibians was fewer both in species and quantities. Without providing the detailed information about the region and counting method of two studies, it is too hasty to come to the conclusion that the scale of amphibians did retract seriously.
Further more, even if amphibians declined in YNP as the author claimed, I doubted that whether it is pollution should take the primary responsibility to the declination. When it comes to the reason, the writer falsely assumed that there are only two reasons would cause the recession-one is pollution, the other is the enemy of trout. In fact, however, there may be more other caused that lead to the situation. Perhaps the recession coincident with a chilly weather change, an epidemic disease, or a large scale of hunting during the period. Large number of amphibians may died of cold or under the hunters' guns. Unless exclude these possibilities mentioned above, the author may safely convinced that pollution is the chief murderer.
Finally, even if the foregoing point was all right, I suspected whether the situation in YNP could be representative for the global one as a whole. What if there had been an epidemic disease spread in NYP region, while amphibians in others were leading a healthy life and breeding properly. As a result, the situation in YNP is exceptional one and could not reflect the overall situation about amphibians at all.
To sum up, this argument was logically flawed and not well supported. To justify it, the author should provide more detailed information about the two studies as well as the further research on reason of ebbing number of amphibians in YNP. At the same time, a global research on amphibians living situation was also necessary to draw the conclusion. Unfortunately, the writer has failed to do all above.