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 argument, the author claims that the decline in deer population was because they could not migrate on their old route. This is based on the on-going global warming happening simultaneously with the decline in deer population reported by local hunters. While this argument may be tenable at first glance, more evidence is need to further evaluate the lines of reasoning behind such claim and the evidence would end up supporting or weakening the argument.

To begin with, the author shows that the loss of sea ice due to global warming has led to the disappearance of deer migration routes. However, we need further evidence as to whether the disappearance of sea ice has reached such a level that the migration routes have all but disappeared. It is well known that whether global warming is sufficient to melt the ice connecting the different islands depends on the extent of the increase in temperature and the thickness of the ice itself. Therefore, we need further information about the extent of the temperature rise and the thickness of the ice sheet. First, if there is evidence proving that recent global warming has not been high enough, then it is reasonable to maintain that the glaciers have not melted enough to make it impossible for deer to migrate. Thus, the argument is weakened. On top of that, even if there is evidence of a very large temperature increase, we still need additional evidence to tell us about the thickness of the ice sheets. If there is evidence showing that the ice in the Arctic is so thick that even if global warming melted the ice somewhat, there could still be plenty of ice left to support the route of deer migration, then the original argument would be unreasonable and the conclusion of the article would be weakened. Any evidence to the contrary, however, would strengthen the conclusion of the original article.

In addition, we need to know if the reports of local hunters are accurate and reliable. This is because the hunters' reports are based on their observations, which can be influenced by a number of factors. First, the time that hunters are out hunting may coincide with a time when deer will not be out in the open. Therefore, we need evidence from a longer period of observation to evaluate the reliability of hunters' reports, such as a month-long, 24-hour-a-day observation. If this evidence suggests that deer sightings are rare regardless of the time period, the original text would be strengthened. Second, it is possible that during long periods of human-animal interaction, northern deer may have learned to avoid hunters. We therefore need a more objective survey, one that would not itself interfere with deer activity. If this survey shows that deer appearances are in fact little changed from the past and that it shows far more deer than hunters report, then the author’s conclusion is weakened.

Finally, even if we accept that the hunters' reports are accurate and reliable and that rising temperatures are really causing deer migration routes to disappear, we still need to know the real factors behind the decline in deer populations. This is because two things happening at the same time does not necessarily mean that there is a causal relationship between them. Therefore, we need to fully consider the various causes that can lead to deer declines. Further evidence to determine if the Arctic was experiencing a plague, food shortage, or an increase in predators during this time period would help us evaluate the author's point. If there is evidence that none of these factors occurred, then we would believe the author's conclusion. However, any evidence that something else was occurring at the time that could have contributed to the deer decline, then the credibility of the article is undermined.

In sum, we can only fully evaluate the author's conclusion if we fully consider all of the above evidence.

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