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题目:ARGUMENT 47 - 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.
字数:392 用时:0:30:00 日期:2003-1-1
The author asserts that the cooling in the mid-sixth century was probably caused by a volcanic eruption. To support his or her assertion, the author cites some accounts found both in Asia and Europe mention a dimming of the sun and extremely cold temperatures. Besides, the author also asserts that some Asian records which mention a loud boom is consistent with a volcanic eruption while there are no records on the bright flash of light created by the a large meteorite. However, this assertion has several flaws, which render it wholly unpersuasive as it stands.
Firstly, the author commits a fallacy of false dilemma between meteorite collision and the eruption of the volcano. It is highly possible that there are other causes to result in the global cold temperature. Maybe the cold weather is not caused by the dimming of the sun, but some internal geographic changes and reactions of the earth itself, which largely exhausted the internal energy of the earth, and therefore it leads to a decrease in surface temperature. Besides, it is also possible the cold temperature is resulted from some factors of the sun, and therefore during this period, all the planets around the sun suffer from a decrease in temperature. Therefore, without ruling out these or other scenarios, the author could not confidently assert that the extremely cold is exactly caused by the dimming of the sun.
Secondly, the author establishes a correlation between the extremely cold and the dimming of the sun and asserts the extremely cold is exactly caused by the dimming of the sun, which is unsubstantiated. It is true that the two phenomena existed during the same period, yet it could not lead to the conclusion that one is the other's cause. Besides, the author concludes the general cause of the global cold temperatures only by some Asian and Europe records, which is not representative. Maybe in Africa and America, there never be the records of dimming of the sun and thus the conclusion is widely adapted. Thus, unless the author offers persuasive and representative evidence that the cold weather is caused by the dimming of the sun, the assertion will remain unconvincing.
Finally, even though the cold weather is caused by the dimming of the sun, still the author also commits a fallacy of incomplete comparison between the meteorite collision and the eruption of the volcano. The author concludes that the cool temperature in the mid-sixth century was caused by a volcanic eruption because of the records of a loud boom, which is illogical. It is possible that the meteorite collision also creates a loud boom. Besides, since the bright flash is too suddenly, then lack of detailed record of the bright flash of light is reasonable. Additionally, maybe the ancient people recorded some other characters of the meteorite collision instead. Consequently, the author fails to conduct a complete comparison and eventually makes the assertion untenable.
In sum, the assertion which seems logical at first has several flaws within it. To strengthen this assertion, the author should prove that extremely cold is just the cause of the dimming of the sun. Furthermore, the author should take other possibilities, which could result in the cold temperature, into consideration.
[ 本帖最后由 phoenixlw 于 2007-8-20 14:14 编辑 ] |
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