[Big Fish]3月3日Argument150 by-Sansouci

SansouciUID: 2755036

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."
In this argument, the author claims that Yosemite decline due to global pollution of water and air, not because the introduction of trout. To substantiate the conclusion, the auger cites a compare of amphibians’ population in Yosemite National Park in California, in 1915 vs. in 1992, respectively. Additionally, the arguer assumes that the introduction of trout is known to eat amphibian eggs. This argument is unconvincing for several critical fallacies.
First of all, a specific case in Yosemite National Park could hardly be representative of the situation throughout the world, because the author provides only amphibians in Yosemite National Park in California samples, however, no more than one region situation might not be representative of the whole general group. Thus we cannot accept the author’s conclusion that numbers of amphibians is decreased all over the world before the arguer could provide more statistic data about the situation of amphibians in other region.
Even if the global tendency showing clear trends that the level of pollution doesn’t necessarily apply to Yosemite National Park in California. It is quite possible that local residents emphasize protect environment, so local ecosystem is keeping balance; there is little water and air pollution. Thus, the global trend, that the argument cites amount to scant evidence that information concerning the level of pollution at different regions, the assumption that pollution is responsible for the decline in the numbers of amphibians everywhere is unwarranted.
Even if the decline in amphibian populations in Yosemite is believable, in explaining the reason for the decline of amphibians the author is presenting a false dilemma. The author ignores factors other than the pollution and the introduction of trout which could explain the decline in amphibian numbers in Yosemite. It is greatly possible that amphibians can’t adapt surround circumstance or this species’ procreate is an obstacle. Before ruling out all the possibilities above, the author could not convince us that there are only those two possible explanations for us to accept.
To conclude, this argument is not persuasive as it stands. To make it logically acceptable, the arguer would have to demonstrate whether numbers of amphibians turn down in global area. What’s more, the arguer must provide evidence to rule out other possible causes of the decline in amphibians populations.