Argument150 高频第十二

Argument150 高频第十二

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."

Argument

The letter claims that the decline in the number of amphibians in Yosemite is resulted from the pollution of air and water instead of the introduction of trout. The author includes the statistical data of 1915 and 1992 to indicate this statement. While in my opinion this argument is entirely unconvincing.

To begin with, there is no clear evidence to indicate the causal relationship between the pollution and decline. Hence, the reason why the number of amphibian is declined can be multiple, such as the climate change or migration of the animals they feed on. It is even possible that the decline is resulted from a sudden epidemic. Therefore, unless the author can rule out the other reasons why number of amphibians is declined and prove the causal relationship, I'll remain unconvinced.

Secondly, it is entirely possible for the introduction of trout that really caused the decline of amphibian number. Taking the fact into consideration that trout is possibly a kind of predator which feed on those number declined amphibians, this phenomenon is very likely to be explained. Otherwise, it is also very possible that the introduction of trout resulted in a competition on the same source of food and caused the decline. Thus, unless the author proves there is no possible relationship between the introduction and decline, the argument is unpersuasive.

Thirdly, the statistical data cited in the argument is probably unreliable especially consider that the data only bases on observation. Very likely the data is unrepresentative to the number of amphibians of Yosemite for the too few observation and careless conductors. In addition, the observation of amphibians might not cover the whole area of Yosemite also could result in this false conclusion. Therefore, unless the author can prove that the statistical data which used to support the claim, the argument is not justified.

In conclusion, the argument is consisted with assumptions that are not justified and render it unconvincing. To bolster it the author must provide solid evidence to support the causal relationship between the environmental pollution and the decline of amphibian. Also needed is the evidence to prove there is no affection from the introduction of trout towards the