理发店悖论(Barbershop Paradox)——欧美十大哲学与科幻悖论

理发店悖论(Barbershop Paradox)——欧美十大哲学与科幻悖论在《欧美十大哲学与科幻悖论》中排名第9名。我们精选了部分网友观点： ...

理发店悖论欧美十大哲学与科幻悖论在欧美十大哲学与科幻悖论中排名第9名。

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这个悖论是刘易斯·卡罗尔在他的一篇文章中提出的这位：乔叔叔吉姆叔叔正走向理发店。有三个理发师在店里生活和工作——艾伦、布朗和卡尔——但不是所有的人都在店里。卡尔是个好理发师，吉姆叔叔很想被剃光他。他知道商店开门了，所以至少有一个人在里面。他还知道艾伦是个非常紧张的人，所以他总是在布朗不跟他走的情况下离开商店。乔叔叔坚持卡尔肯定在里面，然后声称他能从逻辑上证明这一点。吉姆叔叔要求证据。乔叔叔的理由如下。假设卡尔不在。如果卡尔不在，那么如果艾伦也不在，布朗就必须在“因为必须有人在商店里才能开门营业。然而，我们知道，每当艾伦出去时，他都会带着布朗一起出去，因此，我们一般都知道，如果艾伦出局，布朗出局。所以如果卡尔是..更多-基特雷特斯努

This paradox was laid down by Lewis Carroll in one of his stories. The wikipedia article states this:Uncle Joe and Uncle Jim are walking to the barber shop. There are three barbers who live and work in the shop - Allen, Brown, and Carr - but not all of them are always in the shop. Carr is a good barber, and Uncle Jim is keen to be shaved by him. He knows that the shop is open, so at least one of them must be in. He also knows that Allen is a very nervous man, so that he never leaves the shop without Brown going with him.Uncle Joe insists that Carr is certain to be in, and then claims that he can prove it logically. Uncle Jim demands the proof. Uncle Joe reasons as follows.Suppose that Carr is out. If Carr is out, then if Allen is also out Brown would have to be in "since someone must be in the shop for it to be open. However, we know that whenever Allen goes out he takes Brown with him, and thus we know as a general rule that if Allen is out, Brown is out. So if Carr is ... more - Kiteretsunu