[a习作temp] argument47 越写越麻木。。。。。 [复制链接]

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发表于 2007-4-7 18:53:37 |只看该作者 |倒序浏览

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: 528 TIME: 0:25:26 DATE: 2007-4-7

The author concludes that the sudden cooling of the earth is due to the volcanic eruption. However, this conclusion is unconvincing because it is merely based on unsound causality and dubious evidence.

To begin with, the accounts from Asia and Europe do not necessarily indicate that there was a sudden cooling in the mid-sixth century. First, the dimming of the sun is not equal with the decline of temperature. The author fails to exclude other possible explanations. For instance, maybe the dimming was just caused by the mass cloud without cooling weather. Besides, the description of extremely temperature is too vague to demonstrate the weather is cold. As we know, everyone has different sense of temperature. Some may feel cold in the winter while some fell it is just normal. Especially when we consider that the ancient people did not have many modern machines to produce heat such as air-condition, their standard for extreme coldness may be just a normal temperature in the winter. Without excluding other possible explanations, they author fails to convince us with his or her conclusion.

What is more, even if the sudden cooling by the accounts is proved to be true, it is still too hasty to conclude that the whole Earth became significantly cooler. Common sense tell us that the weather varies a lot from one place to another, even within the same country, no mention to different continents. If the America and Africa did not experience a sudden cooling at that time, the author's premise that there was a global cooling is questionable.

Finally, granted the there was a global sudden cooling at that time, the real reason for the cooling is disputable. First, the author imposes a either-or choices which is unwarranted. There are other explanations for the sudden cooling beside the two presented by the author. For instance, the sudden change of ocean currents can lead to the drastic change of weather. Furthermore, even if the author successfully excludes other possible explanations, the real reason for the cooling is still uncertain. The fact that no historical record for the flash was found does not mean there was no such flash. Probably the record was destroyed in the long history because of war, erosion, or the like. Or maybe at that time the meteor collided the Africa and consequently we can not find any record in Asia. In addition, there is no sound proof that the loud boom was caused by eruption of volcano. The boom could be caused by other reason, including the collision of a meteor. Furthermore, if people can hear the loud boom of volcanic eruption, probably they can also see the eruption in sight or felt the earth quake resulted from the eruption. Since there is no mention about seeing the eruption, then it might not happen at that time. The author needs further investigation for the real reason of the sudden cooling.

In sum, the conclusion is open to question because it suffers many flaws. To substantiate the conclusion, the author needs to find more detailed record about the existence of the sudden cooling across the world. Besides, more studies should be carried out to research on the real reason for the cooling.