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feifei 49-50

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楼主
发表于 2009-2-25 22:39:00 | 只看该作者

feifei 49-50

Joseph: My encyclopedia says that the mathematician Pierre de Fermat died in 1665 without leaving behind any written proof for a theorem that he claimed nonetheless to have proved. Probably this alleged theorem simply cannot be proved, since---as the article points out---no one else has been able to prove it. Therefore it is likely that Fermat was either lying or else mistaken when he made his claim.

Laura: Your encyclopedia is out of date. Recently someone has in fact proved Fermat’s theorem. And since the theorem is provable, your claim---that Fermat was lying or mistaken---clearly is wrong.

Which one of the following most accurately describes a reasoning error in Laura’s argument?

(A) It purports to establish its conclusion by making a claim that, if true, would actually contradict that conclusion.

(B) It mistakenly assumes that the quality of a person’s character can legitimately be taken to guarantee the accuracy of the claims that person has made.

(C) It mistakes something that is necessary for its conclusion to follow for something that ensures that the conclusion follows.

(D) It uses the term “provable” without defining it.

(E) It fails to distinguish between a true claim that has mistakenly between believed to be false and a false claim that has mistakenly been believed to be true.

答案:B 好像是说把充分条件当作必要条件了。这题我还是不太明白  希望得到高手指教

沙发
 楼主| 发表于 2009-2-25 22:42:00 | 只看该作者

Joseph: My encyclopedia says that the mathematician Pierre de Fermat died in 1665 without leaving behind any written proof for a theorem that he claimed nonetheless to have proved. Probably this alleged theorem simply cannot be proved, since---as the article points out---no one else has been able to prove it. Therefore it is likely that Fermat was either lying or else mistaken when he made his claim.

Laura: Your encyclopedia is out of date. Recently someone has in fact proved Fermat’s theorem. And since the theorem is provable, your claim---that Fermat was lying or mistaken---clearly is wrong.

Which one of the following most accurately describes a reasoning error in Laura’s argument?

(A) It purports to establish its conclusion by making a claim that, if true, would actually contradict that conclusion.

(B) It mistakenly assumes that the quality of a person’s character can legitimately be taken to guarantee the accuracy of the claims that person has made.

(C) It mistakes something that is necessary for its conclusion to follow for something that ensures that the conclusion follows.

(D) It uses the term “provable” without defining it.

(E) It fails to distinguish between a true claim that has mistakenly between believed to be false and a false claim that has mistakenly been believed to be true.

答案:B 好像是说把充分条件当作必要条件了。这题我还是不太明白  希望得到高手指教

板凳
发表于 2009-2-26 12:23:00 | 只看该作者
地板
 楼主| 发表于 2009-2-26 12:24:00 | 只看该作者

自问自答一下吧。答案是C 将充分条件当作了必要条件。 只要“定理不能证明”他就“撒谎或犯错”,显然充分条件只要“定理能证明”他就“不撒谎”这样取非是不能推出的。  如:只要天下雨地就湿,无法推出天不下雨地就不湿。而必要条件,只有A才B ,那么没有A 就没有B是可以推出的!

5#
 楼主| 发表于 2009-2-26 12:25:00 | 只看该作者
谢谢了。我也想通了
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