- 最后登录
- 2013-3-19
- 在线时间
- 100 小时
- 寄托币
- 221
- 声望
- 30
- 注册时间
- 2008-10-29
- 阅读权限
- 20
- 帖子
- 3
- 精华
- 0
- 积分
- 159
- UID
- 2565269
 
- 声望
- 30
- 寄托币
- 221
- 注册时间
- 2008-10-29
- 精华
- 0
- 帖子
- 3
|
本帖最后由 wywcgs 于 2011-8-30 22:15 编辑
Arctic deer live on islands in Canada's arctic regions. They search for food by moving over ice from island to island during the course of the 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 purported decline in deer populations is the result of the deer's being unable to follow their age-old migration patterns across the frozen sea.
Write a response in which you discuss what specific evidence is needed to evaluate the argument and explain how the evidence would weaken or strengthen the argument.
----------------------------
In the arguer’s paper, he claimed that the decline in deer populations is the result of deer's being unable to follow their age-old migration patterns across the frozen sea. To support his conclusion, he quoted the hunters’ report about the deceasing of deer populations and claimed that the global warming which melted the ice was relevant to this phenomenon. Although it sounds reasonable at the first glance, he arguer failed to provide several essential evidences, which made his reasoning very weak.
Firstly, the arguer thought the report of local hunter could correctly reflect the real trends of deer populations, which is not so obvious. As we know, few people can observe all regions in these islands where deer live. Maybe that most of deer are living in the regions where the hunters cannot see, which made the reports about the declining of deer less convincing. It’s also possible that the hunters’ observing time is just the time when the deer’s activity is decreasing, so they cannot find as many deer as usual of course. There are so many reasons which may lead to the result of these reports, and the arguer didn’t provide any evidence to prove his suggestion.
Secondly, the deer's being unable to migration in the presence of the global warming trends suggests but cannot prove the causality between them. The reason why they don’t migration is vary. Perhaps the environment becomes too bad where they often migrated. For example, their favorite plants in this area may be too few to feed them hence they are not willing to migrate any more. The arguer should provide evidence about the situation of the environment they used to migrate if he wants to refute this possibility.
Even we have got enough evidence to support above two statements, the declining of deer populations, the arguer didn’t prove that the declining was caused by the deer's being unable to migration. Since we have known that there are local hunters, it’s possible that it is the hunters who killed too many deer. The evidence about the quantity of the deer killed by hunters is required to evaluate this possibility. The activity of animals which hunt deer for food is also an important factor. Of course the more activity these animals do, the less the number of deer is. So the research on the activity of these animals is also important. If the effect of hunters and animals is too significant to be ignored according to the evidence, the arguer’s conclusion will fail.
To sum up, the reason why the population of a kind of animal declined is complicated. It’s not as obvious as the arguer thought. To support his conclusion, he must provide more evidence to exclude other possibilities. |
|