TXT argument45 拍~

冬木琉璃UID: 2752392

TOPIC: ARGUMENT45 - 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."
WORDS: 479
TIME: 00:30:00
DATE: 2010-8-19 22:51:12

The author claims that the decline in arctic deer populations is the result of deer being unable to follow their age-old migration patterns across the frozen in that the global warming trends have caused the sea ice to melt. To support his claim, he cites reports by local hunters and the normal behavior of arctic deer. At first sight, the claim seems reasonable. Careful examination of the evidences, however, reveals that the they lend little support the author's conclusion.

First, the author assumes that the number of arctic deer declined merely based on the reports from local hunters. However, this is not sufficient to prove that population of arctic deer really declined. Possibly, hunters witnessed fewer deer just because deer generally noticed the existence of hunters and moved from the area where hunters can find to more secretive shelters for fear of being caught and killed. Or that the population of deer declined only in the area that hunters resided in, and this declining trend is not happening worldwide. If either of this were true, the author's conclusion would be impaired.

Even assuming that the deer population are really declining, the author still commits a logical fallacy by assuming that the global warming trends are effective to influence the ice on which deer use to travel from one island to another land. The author mentions that, if it is cold enough for the ice to cover the sea separating the islands during some of the year, rather than all around the year, then arctic deer can travel over it. However, without informing us how the global warming trends posed on the melting of those ice, it's entirely possible that it fail to melt those ices at all, or though causing those ice melting during certain time of a year, they can still exist during other time of the year.

Even if the global warming trends really cause the ice, which functioning as a passageway, to melt and never frozen again for all around the year, the conclusion is still unsubstantiated in that author unfairly assumes that this change attributes, at least partly, to the declination of deer population. Without evidences, it's possible that the migration patterns fail to threaten the life of deer, and it's other factors such as the scarcity of food, that lead the population of deer to decline. If so, the author cannot convince me that his conclusion is right.

In sum, merely based on dubious evidences and unwarranted assumptions, the conclusion reached in the argument is invalid and misleading. To make it logically accepted, the author have to provide more evidence to convince me that deer population really declined, and that the global warming trends can melting all the ices which act as passageway permanently. He should also rule out other possibilities that may cause the declination of deer, to make his conclusion more substantiated.