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一直搞不清if than推理与因果型推理有什么区别，拿lawyer老师曾经举过的一个例子来说：
24小时上CD就一定能考800分。前后是是充分必要关系：IF24小时上CD，THEN 能考800分。
24小时上CD导致我考800分。前后是因果关系：24小时上CD，so 我考800分。
我想问的是对于第一个，命题“if 没有24小时上cd，then不能考800分”（逆命题）肯定是错的
而对于第二个，命题“没有24小时上cd，so不能考800分”是否正确呢？有一道lsat逻辑题（lsat-10-23）似乎就是这种推理：
23. Farm animals have certain behavioral tendencies that result from the evolutionary history of these species. By imposing on these animals a type of organization that conflicts with their behavioral tendencies, current farm-management practices cause the animals more pain and distress than do practices that more closely conform to the animals’ behavioral tendencies. Because the animals tend to resist this type of organization, current practices can also be less efficient than those other farm-management practices.
If the statements above are true, which one of the following can be properly inferred from them?
(A) Some of the behavioral tendencies of farm animals can be altered by efficient farm-management practices.
(B) In order to implement efficient farm-management practices, it is necessary to be familiar with the evolutionary history of farm animals.
(C) In order to create farm-management practices that cause less pain and distress to farm animals, a significant loss of efficiency will be required.
(D) Farm-management practices that cause the least amount pf pain and distress to farm animals are also the most efficient management practices.（E）
(E) Some changes in farm-management practices that lessen the pain and distress experienced by farm animals can result in gains in efficiency.
答案e是原文的逆命题啊，逆命题怎么能够properly infer呢？
请大家指点迷津，不胜感激！
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发表于 2004-12-9 05:52:00
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