理發店悖論(Barbershop Paradox)——歐美十大哲學與科幻悖論

理發店悖論(Barbershop Paradox)——歐美十大哲學與科幻悖論在《歐美十大哲學與科幻悖論》中排名第9名。我們精選了部分網友觀點： ...

理發店悖論歐美十大哲學與科幻悖論在歐美十大哲學與科幻悖論中排名第9名。

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這個悖論是劉易斯·卡羅爾在他的一篇文章中提出的這位：喬叔叔吉姆叔叔正走向理發店。有三個理發師在店里生活和工作——艾倫、布朗和卡爾——但不是所有的人都在店里。卡爾是個好理發師，吉姆叔叔很想被剃光他。他知道商店開門了，所以至少有一個人在里面。他還知道艾倫是個非常緊張的人，所以他總是在布朗不跟他走的情況下離開商店。喬叔叔堅持卡爾肯定在里面，然后聲稱他能從邏輯上證明這一點。吉姆叔叔要求證據。喬叔叔的理由如下。假設卡爾不在。如果卡爾不在，那么如果艾倫也不在，布朗就必須在“因為必須有人在商店里才能開門營業。然而，我們知道，每當艾倫出去時，他都會帶著布朗一起出去，因此，我們一般都知道，如果艾倫出局，布朗出局。所以如果卡爾是..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