三值逻辑与意义理论

Three-Valued Logic and the Theory of Meaning

乌卡谢维奇的三值逻辑反对古典逻辑的矛盾律和排中律,引起了一系列哲学问题。古典逻辑的基础是二值原则,即任何句子要么是真的要么是假的。乌卡谢维奇把第三值指派给不能确定真假的句子。如何理解第三值是三值逻辑的关键问题。从意义理论的角度看,既不真也不假的句子被赋予第三值是因为它们的真之条件未能得到理解而造成的。对于"明天将有海战"这样的时态句子,运用时态逻辑的语义学,第三值是可以消除的。

Lukasiewicz's three-valued logic refutes the law of contradiction and the law of excluded middle.Thus a series of philosophical problems are produced.The foundation of classical logic is the bivalence principle,i.e.,any sentence is either true or false.ukasiewicz assigned the third logical value to sentences which are neither true nor false.The crucial problem of three-valued logic is how to understand the third logical value.From the view point of meaning theory,the reason for assigning the third logical value to those sentences that are neither true nor false is that their truth conditions are not understood.By using the semantics of tense logic,the third logical value for the temporal sentence'there will be sea battles tomorrow'can be eliminated.