argumen47 [SJTU-ETB6 10G]第四次作业

zhangjunhaoUID: 2276310

TOPIC: ARGUMENT47 - Scientists studying historical weather patterns have discovered that in the mid-sixth century, Earth suddenly became significantly cooler. Although few historical records survive from that time, some accounts found both in Asia and Europe mention a dimming of the sun and extremely cold temperatures. Either a huge volcanic eruption or a large meteorite colliding with Earth could have created a large dust cloud throughout Earth's atmosphere that would have been capable of blocking enough sunlight to lower global temperatures significantly. A large meteorite collision, however, would probably create a sudden bright flash of light, and no extant historical records of the time mention such a flash. Some surviving Asian historical records of the time, however, mention a loud boom that would be consistent with a volcanic eruption. Therefore, the cooling was probably caused by a volcanic eruption.
WORDS: 369          TIME: 00:30:00          DATE: 2007-8-4 15:06:31

In this argument, the author concludes that the cooling of the earth was probably caused by a volcanic eruption. But the author commits some severe logic fallacies that I am not convinced the credibility of this conclusion.

First and foremost, the author bases his argument on a fundamental assumption that the cooling of the earth was cause by a dimming of the sun which is only found in Asia and Europe. I cast much doubt on the reliability of such a dimming of the sun. It is entirely possible that the dimming of sun merely occurred in Asia and Europe but rather the whole earth. Or perhaps these accounts are from the fictions which are handed down from that period. Even assuming that the dimming really existed, there isn't any evidence to prove that the cooling had something to do with the dimming of the sun. One possible condition is that the cooling resulted from the changes springed from the interior movement of the earth such as earthquakes and the like. Unless the author could rule out these alternatives, the conclusion is not persuasive.

Secondly, another assumption on which the author bases his conclusion is that the dimming of the sun is due to the large dust cloud which is created by a huge volcanic eruption or a large meteorite colliding with Earth. Yet, this is may not be the case. It is likely that the sun itself leaded to the dimming for the periodical movements at that time. It is equally possible that a celestial object which just moved a certain place prevented the earth from obtaining enough sunlight. The author fails to provide more information about these possibilities, so the conclusion is lack in credibility.

Thirdly, the surviving Asian historical records of the time don't indicate that the volcanic eruption did happen then. The loud boom is likely been cause by other factors such as the collapse of a mountain crest. Furthermore, while the eruption of volcanic may not happen, I can't exclude the possibility of the large meteorite collision just for there wasn't a sudden bright flash of light has been recorded. It is possible that no one had notice the flash at that time. Or perhaps the record for that flash has been lost through the long-term history. Even the record hasn’t been found by us human beings yet. If the author is unable to prove further, the conclusion is not reliable either.

To sum up, the conclusion reached in this argument is not persuasive because the author fails to provide enough cogent evidence to support the conclusion.

[ 本帖最后由 zhangjunhao 于 2007-8-4 19:23 编辑 ]