提纲：1. 需要证明调查的两组人其他情况相同。可能年龄地域有差异
2. 即使两组人情况相同，还需要证明骨折是由喝乳制品引起的
3. 即使骨折是由乳制品引起的，还需要证明参加者的骨折是骨质酥松而不是其他
40.Milk and dairy products are rich in vitamin D andcalcium—substances essential for building and maintaining bones. Many peopletherefore say that a diet rich in dairy products can help prevent osteoporosis,a disease that is linked to both environmental and genetic factors and thatcauses the bones to weaken significantly with age. But a long-term study of alarge number of people found that those who consistently consumed dairy productsthroughout the years of the study have a higher rate of bone fractures than anyother participants in the study. Since bone fractures are symptomatic ofosteoporosis, this study result shows that a diet rich in dairy products mayactually increase, rather than decrease, the risk of osteoporosis.
Write a response in which you discuss whatspecific evidence is needed to evaluate the argument and explain how theevidence would weaken or strengthen the argument.
In the argument, the speaker claims that adiet abundant in dairy products can actually increase the risk of osteoporosisinstead of decreasing it. Although it may seems plausible at a cursory glance,in-depth scrutiny reveals that the evidence the speaker supplies lends littlecredibly support to the argument, and is therefore unconvincing.
First off, the speaker assumes that all theparticipants in the survey are of the same condition. However, withoutsufficient evidence to substantiate this, this assumption is open to doubt.Since the author fails to informs us the detailed information about the participants,chances are that those who have dairy products are mostly elderly who areeasily get bone structure for their old age even if they do not milk, while therest of the participants are young people who have strong resistance to bonestructure. Or perhaps the latter people mentioned above come from areas wherepeople lived there posses genes that enable them less vulnerable to bonefractures. Without considering as well as ruling out these alternativeexplanations, by no means could the author conclude that the survey is reliableand effective.
Moreover, even if the survey is reliable,the mere fact that people who consistently consumed dairy products throughoutthe years of the study have a higher rate of bone fractures than any otherparticipants provides scant evidence that drinking dairy contribute to bonefracture. It is likely the case, however, the author provides no evidence tosupport it. Lacking such evidence, it is entirely possible that those whoconsume dairy do less exercise so that their bones degrade more quickly, increasingthe likelihood of getting bone fracture. It is also possible that these participantsfavor other kind of food which is detrimental for the bone and increase the possibilityof bone fracture. To substantiate this, it is necessary for the speaker toinvestigate thoroughly to make sure that the lifestyle and the food they eatare identical.
Finally, conceding that the forgoingproblems can be provided with sufficient evidence, the claim is stillproblematic in that the speaker assumes that bone fracture is equal to osteoporosis.Nevertheless, bone fractures can be caused by a host of other factors inaddition to osteoporosis. For instance, it is possible that those whofrequently get bone fractures love to play football or basketball, andinevitable are more vulnerable to bone fracture due to the fierce competition.In this case, it is this kind of sport that cause bone fracture rather than osteoporosis.Therefore, this scenario, if true, would serve to undermine the assumption.
In retrospect, it is precipitous to come tothe conclusion that dairy consumption promote bone fracture rather than retardit. To bolster it, the speaker ought to provide evidence to solve the problemsmentioned above. Only by supplying sufficient evidence could the speaker putforward a persuasive and tenable contention. | 
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发表于 2012-6-28 19:29:54
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