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45The following appeared as an editorial in a wildlife journal.
"Arctic deer live on islands in Canada's arctic region. They search for food by moving over ice from island to island during the course of a year. Their habitat is limited to areas warm enough to sustain the plants on which they feed, and cold enough, at least some of the year, for the ice to cover the sea separating the islands, allowing the deer to travel over it. Unfortunately, according to reports from local hunters, the deer populations are declining. Since these reports coincide with recent global warming trends that have caused the sea ice to melt, we can conclude that the decline in arctic deer populations is the result of deer being unable to follow their age-old migration patterns across the frozen sea." Conclusion：鹿的数目下降的原因是气温上升。因为气温上升使得海上的冰融化，鹿无法按照传统在冰冻的海面上迁徒。他举例说，最近当地的猎人报告说鹿的数目在下降，而这种下降又伴随全球气温上升的趋势。
1. 鹿数量的减少可能还有其他原因，例如猎人捕杀，环境变化。
2. 猎人的报告不一定可信。与猎人的活动时间、范围有关。
3. global warming 是使气候变暖，但是否严重到海面的冰都融化的程度。
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In the editorial, the arguer draws a conclusion that the decline of the deer population in Canada is exclusively due to the warming trends which check the deer's regular migration patterns between islands for food. The argument is mainly based on the reports from local hunters that the deer populations are declining. Although at first glance the argument seems cogent, yet there are several logical flaws which make it unconvincing. > In the first place, the arguer fails to rule out other possibilities in the analysis. Perhaps hunters, referred by the arguer, are of highest probability to contribute to the decline in deer population. It is also possible that the decline of food really threats lives of deer because of human beings’ activities and climate change. Even if deer can go across the islands, it is hard to find adequate quantity of food. Without taking these factors into account, the arguer is unable to make the argument persuasive. > Secondly, the reports from local hunters are questionable. For one thing, perhaps the hunters providing reports are all those who live in a certain island or geographic region. If so, the reports can not represent the overall quantity of deer. For another thing, maybe the mass deer are confined in one large island where there is enough food for them to live by, so there is less chance for hunters to see them. In addition, the habits and range of the hunters also influence on the results of the reports. These reasons above mentioned and many other possible ones would undermine the credibility of the reports. > Last but not the least, whether the extent of the global warming is so severe that it is unable to freeze the water on the sea is still uncertain. The arguer provides no evidence to support the assumption that recent global warming trends are able to cause the sea ice to melt. It is highly possible that it is extremely cold in Canada's arctic region where deer live. Despite of the recent global warming leading to the raise of temperature, the temperature is still under zero which is unable to cause the sea ice to melt. If so, the global warming makes no sense to the decline of the deer in Canada's arctic region.
>
In sum, the argument is not persuasive as it stands. To solidify his conclusion, the arguer would have to make a more detailed investigation about the characteristics and quantities of the deer in arctic region, and demonstrate that there is a cause-effect relationship between recent global warming and the decline of the deer. (434words 35min)
[ 本帖最后由 duyuan3377 于 2008-12-7 17:16 编辑 ] | 
发表于 2008-12-7 17:12:27
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