Argument47 by zephrqq

zephyrqqUID: 2260290

题目：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.

提纲：
1没有发现提到强光的记录这一事实，不能排除大型陨星撞击导致降温的可能，1)没有强光不代表没有撞击, 可能有撞击没有强光，所以没有关于强光的记录不要紧2）而且没有记录强光，不代表一定没有强光
2.巨大的响声不一定是火山爆发产生的，陨星撞击也可以产生
3.即使那个响声是火山爆发产生的，仍然不能断定火山爆发引起降温。因为作者没有告诉我们具体的时间，降温完全有可能发生在火山爆发之前
4.即使在降温之前有一次火山爆发，依然有理由怀疑这能不能引起降温。作者指出巨大火山爆发和大型陨星撞击可以导致降温，但是他没有告诉我们这次火山爆发的规模。我们不能知道火山爆发能不能产生足够的灰尘遮蔽日光引起降温。同时，论者忽略了其他可能引起降温的原因

In this argument, the author concludes that the cooling happened suddenly in the mid-sixth century was probably caused by a volcanic eruption. In order to support this conclusion, he analyzes the cause of a dimming of the sun and the extremely cold temperatures by making a comparison between the possibility of a huge volcanic eruption and that  of a large meteorite colliding with the earth. However, the author do little to persuade us.

To begin with, the absence of historical records of the time mention a sudden flash can not prove that a large meteorite colliding with the earth was certainly not the cause of the cooling. First, the author asserts that a large meteorite collision would probably create such a flash of light. However, we can not ruling out the possibility that sometimes it would happen without the company of that light. If this was just the case, no records found about a flash matters nothing. Secondly, no extant records of the time mention such a flash does not necessarily amount to there was not one. Perhaps, it actually happened but was observed by nobody, or was recorded by nobody. If so, we can not firmly excludes the possibility that the cooling might caused by a large meteorite collision happened at that time.

Furthermore, when it comes to the possibility of the happening of a huge volcanic eruption, it is the same: the author's judgment is open to doubt. Although some surviving Asian historical records of the time mentioned a loud boom, the boom would not be necessarily consistent with a volcanic eruption. Perhaps, the loud boom, on the contrary,  is create by a large meteorite collision. Therefore, the surviving Asian historical records lend little to support the author’s perspective.

In addition, even assuming that the loud boom was the result of a volcanic eruption at the time, the eruption did not necessary lead to the cooling. No evidence is provided to show the time of the boom. What if the boom was after the cooling? Without ruling out the possibility that the cooling was actually occurred before the eruption, how can we think it was caused by the eruption?

Finally, even though an eruption indeed  happened before the cooling,  we still have good reason to doubt whether that volcanic eruption could bing a significant cooling. According to the author's statement, either a huge volcanic eruption or a large meteorite colliding with Earth could been able to significantly lower global temperatures. However, it is entirely possible that the eruption was not huge enough and the dust it produced could not from a large cloud, which would be capable of blocking the sunlight to lower the global temperature. Moreover, the author turns a blind eye to alternatives might be responsible for the cooling.

For all this reasons, this argument is not convincing as it stands. Therefore, we can not accept the author's conclusion that the cooling was probably caused by a volcanic eruption.

[ 本帖最后由 zephyrqq 于 2008-3-6 19:39 编辑 ]