Argument47【加州阳光】第五次作业 stone 请猛拍

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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.


In this argument, the speaker asserts that the cooling in the mid-sixth century was probably caused by a volcanic eruption. To support his assertion, the speaker cites the historical records survive from that time. However, after carefully examination, we will find some illogical defects.
  To begin with, the speaker first cites two probable reasons for the cooling of the temperature. Then he or she analyzes the probability of two probable reason, one is a huge volcanic eruption, the other is a large meteorite colliding. While excluding one of the two, the speaker naturally concludes that a volcanic eruption is the reason for this cooling. However, it is entirely possible that the reason for this event is neither the volcanic eruption nor the meteorite collision. May be there are some other possible reasons exist while the speaker does not pay attention to them. Just exclude one of these reasons cannot convince us that his/her conclude is reasonable.
  Secondly, a sudden bright flash of light is one probable reason for the result of a large meteorite collision. Although there is no extant historical records of the time mention such a flash, it does not mean that there is no such a flash at all. Perhaps on account of the ignorance of the ancient people, this flash is missed. So we can’t find any evidence to support this assumption.
Finally, the speaker argues that some surviving Asian historical records mention a loud boom. However, this boom can’t manifest that it is given off by the volcanic eruption. Perhaps there is no such a straightforward relationship between the boom and volcanic eruption. Thus, demonstrating us with unconvincing evidence seems to be cursory.
  In the final analysis, the speaker can not make the conclusion on the basis of excluding one of probable reason. It is highly possible that there are many other reasons for the cooling, unfortunately, the speaker overlooks this probability. To support his assertion, the speaker should provide us more convincing evidences, such as there are really no other possibilities except volcanic eruption and meteorite colliding.