＂我说谎＂的挑战
语言，可以说是属于人类＂熟知而非真知＂的事物之一。
语言存在的问题之一，就是悖论的存在，如＂我说慌＂，这句话使人无法辨认真假。比较经典的还有罗素发现的＂最大集悖论＂问题。一个最大的集，应该包括其他一切集。问题是，它是否应该包括自己？如果不包括，它就不是最大集。如果包括，就违反了＂包括其他一切集＂的规定。
通俗地说，罗素悖论也叫＂理发师悖论＂。一个理发师作广告说，＂我只给全城不自己刮胡子的人刮胡子＂。理发师，很明显，无法确定是否应该给自己刮胡子。因为，按照广告，如果自己不属于＂自己刮胡子＂的人，那么，自己就必须自己给自己刮胡子。而如果自己属于＂给自己刮胡子的人＂，自己就不应该给自己刮胡子。
据说，当福雷格接到罗素的明信片时，立刻叫停了马上就要开印的几卷本的数学基础论著作，它一生努力的工作付之东流。
所以，究竟为什么语言会出现悖论？悖论仅仅是人类语言的错误吗？还是也存在于自然界？我们应该怎样来理解悖论？
等等这些问题，一个世纪以来，人类还在继续寻找答案......
Reference:
"Russell's Paradox
Russell's paradox is the most famous of the logical or set-theoretical paradoxes. The paradox arises within naive set theory by considering the set of all sets that are not members of themselves. Such a set appears to be a member of itself if and only if it is not a member of itself, hence the paradox.
Some sets, such as the set of all teacups, are not members of themselves. Other sets, such as the set of all non-teacups, are members of themselves. Call the set of all sets that are not members of themselves “R.” If R is a member of itself, then by definition it must not be a member of itself. Similarly, if R is not a member of itself, then by definition it must be a member of itself. Discovered by Bertrand Russell in 1901, the paradox has prompted much work in logic, set theory and the philosophy and foundations of mathematics."
