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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."
1.鹿的数目确实减少了？就凭着猎人的判断得出的结论HASTY。天气的变化有可能使鹿改变它们的生活方式，或者使鹿的作息时间有所变化，避开了猎人的捕猎时间。或者可能它们被困在一个食物充足的岛屿上并适应了当地的生活，不在猎人的狩猎范围之内，当然猎人能捕猎到鹿的机会要少了。 2.就算鹿的数目少了，作者也不能下结论是因为气温降低。首先，全球气温的降低不能说明当地气温的下降幅度，而这种下降的幅度是否足以使大量的冰融化，从而阻断了鹿的迁徙路线作者也没有列出足够证据证明。其次，不能排除猎人狩猎的因素还有其他因素导致鹿的死亡。常识告诉我们动物的灭绝和猎人的过量补杀之间存在联系。最后，除了猎人之外，我们不能排除大气污染和鹿本身有可能在最近流行瘟疫等使鹿数量减少的可能性。由上面分析可见，作者一共作了两个假设来构建了这样的一个因果关系，显然是不准确的。 In this argument, the author assumes that the populations of Arctic deer declined and it is because of recent global warming trends. After a close examination, I found this argument unsound on several reasons which I will discuss below.
Firstly, it is unfair to assert that the populations of Arctic deer declined merely depending on the claim of local hunters. There are some factors that make hunters less likely to see deer. Maybe deer's habit is changed. They might appear in the different time from the hunting time of hunter, to just avoid the hunting maybe. Possbily the deer have been trapped on an island where otherwise has enough food and water because of the bad climate or the melted ice which is also assumed in this arguement. If this is the case, in this short period of time the hunters cannot see them too.
Secondly, even assuming that the number of deer exactly declined, the author made two assumptions to claim the cause-effect relationship between the decreased populations and the arisen global temperature. One assumption is that the local temperature is down to the point that a large amount of ice melt and it cannot afford the deer's migration. With the vague fact of global situation, it is quite possible that local temperature is little changed or slightly arisen that cannot affect the deer's normal migration. After all, the temperature difers from place to place and the effect caused by global warming is also not certainly the same. Some places might be quite warm where are badly affected by global warming, while other places like this deer's habitat might be affected little. The other assumption that the author refers is that other factors such as the excessive hunting of hunters and the pollution of environment can be excluded. After all, common sense tells us a great effect from hunters and pollution might be the fatal factors of the decline of deer populations. No evidence can vindicate that hunters are doing an appropriate hunting. Probably the deer was on the verge of elimination, any behaviors like hunting will do significant and fatal effect on them. Further more, pollution is also a serious global problem as global warming. If global warming can make such an obvious effect, how can the factor of pollution be excluded? The pollution of air, water and local food should be meditated.
In sum, this argument is not warranted as it stands. To strengthen his conclusion, the author should provide a close survey of the local hunting of hunters and an examination on the near place where deer search for food and the situation of pollution of local environment.
[ 本帖最后由 Ivyscar 于 2007-7-31 19:36 编辑 ] | 
发表于 2007-7-31 19:01:32
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