本帖最后由 liyao0509 于 2010-6-16 22:24 编辑
45.The 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."
1.The reports from local hunters are not convincible enough.
2. global warming does not necessarily influent the Canada's arctic regions.
3. even the former two are confirmed, decline of deer may not result from global warming.
In this argument, the arguer advocates that decline in arctic deer population, which observed by local hunters, is caused by global warming. As the influence of recent global warming has been rooted deeply among the people, it is tempting to accept the argument at first glance. However, it is in fact ill-conceived. The reasons are stated as follow.
In the first place, the arguer assumes that deer population is declining according to local hunters’ report. Although this is entirely possible, the arguer offers no evidence to substantiate that the decline of the deer population observed by hunters indicates the real decline. After all, hunters are not professional surveyors, so their reports are not convincible enough. It is very likely that deer have changed their daily habit, and their outside activities no longer coincide with hunters’. Another possible situation is that deer move to new areas which are far away from hunters' scope. The arguer’s reasoning is definitely flawed unless the arguer can provide the full-scale and professional investigation result.
In the second place, the arguer assumes that global warming caused the sea ice to melt, which directly effect the living environment of arctic deer. However, as far as I am concerned, what arguer has deduced cannot be regarded as evidence. Global warming, which represents an average trend of the whole world, does not indicate that every area including Canada's arctic region in which Arctic deer live is also affected. It is even possible that the temperature there drops and much water is frozen.
The last but not the least important, even if the evidence turns out to support the foregoing assumptions, the arguer just simply assumes that it is melt of ice, which makes deer unable to follow their age-old migration pattern, then leads to extinction. This result goes against with the former assumption: the deer migrate to other place for seeking food, when the temperature rises, it is quite possible that their habitant maybe warm enough to feed them up with plant, so even their migration pattern has been disturbed, the population would not decline due to starvation.
To sum up, the arguer's argument mentioned above is not based on valid evidence or sound reasoning, neither of which is dispensable for a conclusive argument. In order to draw a better conclusion, the arguer should survey more deeply to find out whether the population of deer is decline, and what the direct reason which causes decline is. Only after rigorously and overall reasearch, could arguer get a reasonable conclusion about Arctic deer living in Canada’s island. | 
GO
发表于 2010-6-16 22:02:06
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