[try best]第一小组 7.7 Argument150

GG86_FlyUID: 2641450

TOPIC: 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."
WORDS: 370
TIME: 00:29:13
DATE: 2009-6-19 Íõè´ 11:55:18

In this letter, the author concludes that the worldwide decline in the number of amphibians is due to the global pollution of water and air. To support this conclusion, the arguer notes two studies in Yosemite National Park, and stresses that the decline of amphibians indeed exists and the trout which eat amphibian eggs are not responsible for the worldwide decline. However, carefully examine the author's reasoning, we may find this letter contains several flaws, which render the author's conclusion unconvincing.

First of all, the author makes an unwarranted assumption that the number of amphibians in Yosemite National Park has declined. It is impossible that the author didn't observe the other three species in the park because of his or her carelessness. Maybe there are still seven species and the number even has increased. Without careful observation and clear evidence, the author cannot convince me that there is a decline of amphibians in Yosemite National Park.

Secondly, the author cannot reasonably make any conclusion about the number of amphibians worldwide based on the study only in California. Even if the number of amphibians in Yosemite National Park decreased, there is no evidence to show that the number of amphibians worldwide also decline. Since the author has said the trout has been blamed for the decline in YN Park, maybe trout eat amphibian eggs thus make the number of amphibians decline only in YN Park.

Thirdly, the author fails to provide any evidence to refute the inference that trout maybe the reason for the decline in Yosemite. Even assuming the decline has happened in a worldwide scale, maybe the number of trout worldwide has drastically increased for certain reasons, since they can eat amphibian eggs, perhaps they are the main reason for the decline. Or maybe there are some other phenomenon rather than air and water pollution caused the decline. Without providing affirmative evidence that air and water pollution instead of trout or other pollutions is the reason for the decline, the author cannot justifiably assert that the global pollution of water and air is the reason.

To sum up, the author's conclusion is convincing as it stands. To better support this argument, the author should provide clear evidence that there is a decline of amphibians in Yosemite National Park and other areas in the world. He or she should also convince us that trout are not responsible for the decline while the global pollution of water and air is.

小红莓UID: 2641349

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