argument45 欢迎指正~

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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."

This argument is not cogent because it provides us unconvincing evidence that the recent global warming causes the decline in arctic deer populations in Canada. In addition, the author ignores other facts that lead to the decline.

To begin with, does it mean that recent global warming will result in the lift of temperature in Canada's arctic region? Why don’t the tempertature decrease? The conception of "global warming" simply means that the temperature of the earth increases entirely. Some parts may be warmer than it past, while others may be colder, but in consideration of the whole earth, it is warmer than ever. From this point, the temperature of local region may be the same as it before, or even has a decrease. Therefore, the assertion that global warming causes the sea ice to melt in Canada's arctic region is unwarranted.

Second, even if the temperature increases in this region, it does not mean the decline of deer populations. Perhaps the increase of the temperature does not reach the degree that will cause the sea ice to melt. Even if it does, the travel over the sea ice is not the only way for the deer to survive the island. For example, in light of the Darwin's law of natural selection, the deer is apt to have their normal habits changed to adapt to the changes of the environment, such as embracing a eating habit of various kinds of food. Even if the sea ice has melted due to the changes of temperature and then become one cause of the decline of the deer population, the author ignores other facts that may account for the decline, such as the excessive hunting and the tremendous change of the climate.

Moreover, the author fails to provide us convincing evidence that the number of deer does indeed decrease, because the evidence is based on the hunters' personal experience. It is possible that there are many deer that the hunters fail to see. Perhaps the number of the deer is counted in winter when deer are not inclined to walk around due of the lack of food in the barren area.

In sum, we can't find powerful evidence to support the conclusion that the decline of the arctic deer populations is caused by the failure of their migration across the frozen sea. To get the convincing evidence, the author should make all-round and deep study about the authentic reason.