求解~~谢谢各位！狒狒逻辑

Sophin

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Laura: Your encyclopedia is out of date.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.

我个人的思路：
J：百科全书说P声称自己证明了理论，但没有任何证据他证明了，（也许是因为这个理论无法被证明）就像文章中说的没有人证明出来，因此，P这个人要不是撒谎或者他的理论就是错的。

L：......最近有人证明出来了，所以J的观点（P要么撒谎，要么理论就是错的）不对


请教各位的是：我就是怎么也推不出C（充分性和必要性），觉得即使是从“J的观点不对”推导出“L说有人证明出来”也没道理啊。。。


50. 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：C

Sophin

。。。。。。。怎么没有回复。。。。。。

Gail小M

error in the reasoning : even the theorem is provable( the argument mentions someone has proved the theorem) ----can not lead to the conclusion that mathematician Pierre de Fermat had proved the theorem.

J:premise1:no written proof
  premise2ROBABLY this alleged theorem simply cannot be proved
  conclusion: Fermat was either lying or else mistaken when he made his claim.

L:premise:someone has proved the theorem
 conclusion:your claim---that Fermat was lying or mistaken---clearly is wrong.

C: 仅仅表明理论是可以被论证的不能构成因果关系表明Fermat也论证过这个理论。in the argument of J, he just points out a possilbe reason that may lead to his conclusion.