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: 513 TIME: 01:11:49 DATE: 2008-10-5 11:26:13
The author of this argument claims that the abnormal cold weather in the mid-sixth century resulted from a volcanic eruption. To justify this claim, the arguer cites historical records about a dimming of the sun and a loud boom. Moreover, he or she also points out that no evidence of a meteorite collision was recorded. This excerpt seems to be convincing and plausible; however, after close scrutiny, I find it contains logical flaws in several critical respects, as the following discussion shows.
To begin with, the argument relies on the unwarranted assumption that the extraordinarily low temperature was attributable to the dimming of the sun which was observed by ancient Europeans and Asians. Yet, the only foundation for this causal relation is that these two events occurred simultaneously. It is equally possible that other factors were instead reasons for the abnormal climate. Perhaps activities of aerosphere suffered from a unusual change in those decades and the global climate saw a variation which led average temperature in Asia and Europe dropped greatly. Without ruling out this or other similar possibilities, the arguer's conclusion remains unsubstantiated.
Additionally, even if the lack of sunshine was the reason for global cooling, the author assumes too hasty that either a meteorite collision or a volcanic eruption led to the sun dimming. Although these are entirely possible, common sense and experience inform me that they are not the only explanations. Perhaps there was an unobserved forest fire during these years, which could also produce large amount of smoke to dim the sun; or perhaps solar eclipse occurred frequently in the mid-sixth century and those ancient people consider it was the symbol the sun dimming. Since the arguer failed to weight and eliminate these explanations, the arguer's assertion cannot be taken seriously.
Finally, even I concede that one of the two reasons listed by the argument was responsible for the significant dropping of the temperature; the speaker cannot confidently draw the conclusion that volcanic eruption instead of meteorite collision was the probably explanation. The mere fact that no bright flash was recorded does indicate that no meteorite collision happened. Perhaps the meteorite crash into the continent of Africa; thus people lived in Europe and Asia cannot spot the flash, but the smoke and dust can still affect the whole planet. Similarly, the arguer insufficiently proves that the loud boom was the result of volcanic eruption. Oppositely, there was a great chance that it was the meteorite collision that led to his boom.
To sum up, the author's conclusion about the cause of the global cooling in the mid-sixth century is not well reasoned. To bolster his or her argument, the speaker must prove that the lack of sun light necessarily contribute to the cold weather. Similarly, to better support the conclusion, the author is expected to provide more information which can prove that there were no other reasons for the dimming of sun. Furthermore, to make it logically acceptable, the arguer should also sufficiently demonstrate that, in that period, a volcanic eruption did occur and no meteorite collided into Earth.