第一次限時，argument 150，求拍

長安UID: 2573189

第一次限時，太不堪……還有16天考試了，惶恐T_T
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長安UID: 2573189

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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第一次限時，惶恐，求拍

This argument looks tenable at first glimpse, but further scrutiny raises several fallacies.
First of all, the author maintains that according to a survey conducted in Yosemite Natural Park, where both the number and the species of amphibians fall drastically from 1915 to 1992, the disappearing species and lost numbers of amphibians are attributed to pollution. But the premise that there are lost species remains weak, the unobserved 3 species of amphibians may be still exist, they just migrate to somewhere else or simply doggo in the mountainous area in the park.

Even if the decrease of the number and species was a true fact, it does not directly leads to the conclusion that the air and water in the park are polluted. Here the author commits a circular reasoning mistake. It is not the decreased number of amphibians that indicates pollution, but pollution foreshadows the loss of animals. To start with, the argument offers nothing in detail about the environmental situation of the park. To convince me that the park's water and air are contaminated, I need to know the exact numbers of hard precise official evaluation of its environment. For example, specific analysis of the park's water quality, and its air quality. Only when the numbers indicates a slash of environmental statistics will it convince me that the park is polluted.

Nevertheless, even though it is true that Yosemite's water and air quality turns out be questionable, it does necessarily present itself as the sole contribution to the extinction of species. As mentioned by the author, there is another factor which potentially pushes those amphibians into death, trouts. The park has been introducing trouts, which feeds on the eggs of amphibians, for more than 70 years, the large existence of trouts pose a impressive threat on the survival of amphibians. Probably, They may be eaten by trouts, thus comes the decline of  amphibian numbers. Or, the lost variety of amphibians simply has nothing to do with pollution or trouts, the reason could be that they succumbed to natural selection for they fail to adapt themselves to the changing climate. It is nature, instead of others, that takes their course. Also, the drop of number might be an outcome of illegal excessive hunting. Without ruling out these scenarios, the argument could not persuade me to believe that the water and air pollution are solely responsible for the deterioration of amphibians.

Finally, the author falsely expands the analogy to conclude that amphibians are extinguishing globally due to the same reason- water and air pollution in Yosemite park, an unsubstantiated premise in so far.

In final conclusion, the argument is weakened by the failure to establish the deduction that the polluted environment results the decline of amphibians in Yosemite park, and it appears to be unreasonable to hastily generalize that the worldwide tendency precisely tally with Yosemite park.