argument47 南智组娓娓第20次作业

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argument47
47Scientists 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.


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In this argument, the arguer concludes that the reason of the earth cooling in the mid-sixth century was a volcanic eruption. To support the conclusion, the arguer cites some historical records in Asia and Europe and uses some assumptions of him to get results at last. A careful examination of this argument would reveal how groundless it is.

The argument suffers from a fallacy of generalization. The historical records, which explain a dimming of the sun and extremely cold temperatures, cannot be used as an attestation, which have not recorded when this phenomenon happened and the duration. It is possible that happened in winter. Even if the records descript the condition of the earth cooling time indeed, there is no evidence to assume that the cold temperature is due to the blocking sunlight. The record mentioned is a just phenomenon, not causality. As we all know, there are many reasons to cause earth cooling, such as the change of earth orbit, the movement of solar cycle and cosmic rays, all of which are ignored by the arguer. Moreover, even though sunlight blocking is the real reason, the two possibilities, which are a volcanic eruption and a meteorite collision, are unwarranted assumptions, hence there may have several other reasons, like the component change of atmosphere. Therefore, there is no guarantee that either a volcanic eruption or a meteorite collision is the reason of earth cooling.

However, even if the two possibilities may be the reason of temperature decreasing, the arguer has no evidence to eliminate any of them. First, a large volcanic eruption, which the arguer assumes according to Asian historical records, may be unbelievably. Because we cannot prove the truth of the records, and the records just says a boom not a volcanic eruption. Many things can make a boom, such as thunder. Moreover, a volcanic eruption happened in one place, how can the eruption block the sunlight all over the world? Only most of active volcanic erupting at the same period may happen. Second, the arguer does not provide any solid information concerning about a flash which made by a large meteorite collision. No extant historical records to mention the phenomenon, may has several possibilities that it may not happen in the history or the records lose. The later reason may have major possibility because the arguer suggests that few historical records survive from that time. Therefore, there is not enough evidence to choose the reason of a volcanic eruption or meteorite collision or both of them.

In summary, the argument is not persuasive as it stands. Before we accept the conclusion, the arguer must present more facts about historical records and the credibility of them. In addition, the arguer should use science to assume his claim.

[ 本帖最后由 qqwuweiyi 于 2007-2-2 15:54 编辑 ]