论同一替换原则的有效性

哲学界一直关注传统逻辑中同一替换原则失效的问题，弗雷格、罗素等哲学家都曾试图从不同的角度维护该原则。从弗雷格的专名理论和罗素的摹状词理论可以证明，“同一”是概念之间的关系，而不是名称之间的关系。晨星和昏星不是同一概念．同一替换原则没有失效。

The philosophers always pay great interesting to the invalid application of the substitution principle, for instantiation, Freg and Russel have tried to stick up for the principle. Their theories about proper names and descriptions could prove that the ＂identifi- cation＂ is about the relationship between concepts but not the relationship between names. The morning star is not equal to the evening star, and the substitution principle is not invalid.