Argument47 【加州阳光】第五次作业 sandy 拍呀

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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: 476          TIME: 0:54:27          DATE: 2006-6-28

In this analysis, the arguer claims that a volcanic eruption causes a dimming of the sun and extremely cold temperatures in the mid-sixth century. To justify his claim, the arguer points out that either a huge volcanic eruption or a large meteorite colliding with earth could lead to the cooler climate of the earth. In addition, the arguer also uses the evidence to support the argument that the historical records talk about the loud boom consisting with the volcanic eruption. Although this conclusion seems rational at first glance, in carefully investigating, the argument lies in several critical fallacies.

To begin with, the arguer does not consider all the aspects leading to the cooler climate in the mid-sixth century.  The arguer only mentions the two possibility of the decreasing of the temperatures: the meteorite colliding and the volcanic eruption.  Some aspects like the warm current of the word area or the El Nino phenomena may also result in such climate. Scientists should take all the affecting aspects into account and provide the evidence to testify the cool climate only related to these two reasons.

In addition, the argument fails to convince us that no large meteorite colliding ever occurred in the mid-sixth evidence. First of all, the arguer denies the possibility of the meteorite colliding for no extant historical records of a flash. Nevertheless, the arguer confess that a sudden bright flash of light, being a potential phenomena, may be not seen by the ancients; other phenomena may also prove the occurrence of the meteorite colliding. At the same time, the argument also mentions the few historical records survived from that time, scientist can not find the related records may means the loss of the related records.  So, more research should be made to ensure the impossibility of the meteorite colliding.

Even if we confess the legitimacy of the above mention, we can not draw the conclusion so soon that a volcanic eruption caused the cooling in the mid-sixth century. Insufficient evidence justifies a volcanic eruption as the reason of the cool climate. The argument does not show the exact content about the records of the volcanic eruption, such as the scale, the duration and the severity.  The volcanic eruption should be great enough to cause a large dust cloud throughout the Earth's atmosphere.  If the scale of the eruption in the records is small one, the record is invalidation to justify the argument's conclusion.  To sum up, more information about the record is need to convince the correct of the conclusion.

To better access this argument, the arguer would have to present more information about the reason why the cooling only possible related to these two causation and impossibility of the meteorite eruption.  In addition, the arguer also shows more evidence to support the idea that the cooling was probably cased by a volcanic eruption.

[ 本帖最后由 sandyfriend 于 2006-7-1 12:39 编辑 ]