狒狒逻辑 50题

nancyyue1219

Questions 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Laura: Your encyclopedia is out of date.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.
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

思路：
Laura的论证过程：该理论已证明—>P没有说谎，他的CLAIM对。理论对并不能表明是P证明的，这只是必要条件，不是充分条件。


我不明白为什么给理论证明了不能说明P没有说谎呢？？为什么不是充分条件啊...还有就是C说的意思是混淆和充分条件和必条件么？？
这类问题总是错啊...求大牛牛指点啊！！

yqhpsyche

Laura's premise is that the theory is provable. The fact that the theory is provable is necessary for the conclusion that Fermat has indeed proved the theory before his death. But this fact alone does not conclusively prove or sufficiently points out that Fermat has proved it. In other words, this fact alone is not a sufficient condition for the conclusion that Fermat has indeed proved the theory.

C points out this err in Laura's argument.

nancyyue1219

先谢一个~
然后...我只能用中文表述我的问题了...
我的困惑是，为什么一定要说是F证明的呢？在最开始J的里面说，因为Ｆ没有证明也没有其他人证明，所以Ｅ是错的或者说了谎
那现在Ｌ说明有其他人（或者是Ｆ）证明了，那不就可以说明Ｆ没有说谎没有错么？？
求拯救求拯救．．．Ｔ＾Ｔ

reginechen

我的理解是，  J说 因为F所认为已经被证明过的理论F没有留下任何材料给出证明，所以，认为F是lying或是mistaken了，因而当L给出有人解释了理论时，其实没有高清J所说话的因果关系。。。  这只是我自己的理解，，，

nancyyue1219

嗯....我再消化一下...