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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.
1.没有排除陨石的原因
2.没有确证是火山
3.其它的原因
In the argument, the author concludes that the cooling of weather in the mid-sixth century was probably caused by a volcanic eruption. Close scrutiny on the evidence, however, reveals that it lends little credible support to the conclusion.
To begin with, the author unfairly assumes that meteorite collision is not the cause of the cooling, however the scant evidence the author provides is scant to support this. No extant historical records of the time mention a flash in the mid-sixth century is little indication that there is no meteorite collision at that time. It is possible that such a collision exist, but as there are many such collision at that time, and people had get use to it, so they did not write it down as they were not important. It is equally possible that people made such record, but during the war or in an accident such as a fire, the record was destroyed. Even possible is that the scientist had not found such record as they may in some place that is mysterious. Without considering these, the author's conclusion that meteorite collision is not the cause of the cooling is open to doubt.
Furthermore, the conclusion based on the presumptuous assumption that cooling is attribute to volcanic eruption. A loud boom may be consistent with a volcanic eruption, yet it is not always the case. Various other phenomenon can result in loud boom, such as earthquake or even the collision of meteorite with the earth. Besides, the author has not substantiated the authenticity of the historical records. If the historical records are based on biased observation, then the conclusion based on it is unwarranted.
Finally, the assumption that the cause of the cold temperature is either a volcanic eruption or meteorite collision is also incredible. The author neglects other possible explanation for the cause of the cold temperature. Perhaps it is because of the sun’s abnormal activity. Or perhaps the glacier in the arctic area begin to thaw somewhat. Without excluding other possible causes, the author's argument would be proved of little avail.
To sum up, the argument is logically flawed. To bolster it, the author has to provide evidence that volcanic eruption occurred and was responsible for the cooling. To better asses the argument, the author also want to exclude other explanation for the cooling.
[ 本帖最后由 abc021900 于 2007-8-18 18:49 编辑 ] |
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