On Carnap's Theory Of Meaning

R.Carnap's meaning theory is a milestone of history of logic. It has great influences on many branches of logic such as modal logic and Montagu's intension logic. Following Rusell and Weittgenstein, Carnap agrees with solving philosophical issues by logical method. He thinks that the object of philosophy is the language rather than the world. The main problem of language is the meaning of language, so the language becomes the central question of philosophy. His meaning theory contains two interrelating aspects: logical and philosophical. The meaning theory is represented by the verification theory of meaning in philosophical term, but it is the logic aspect of meaning theory that is to be discussed in this paper.Carnap's meaning theory experienced a change from logical syntax to semantics in 1935.In the syntactic stage, his whole work can be described as attempts to build criteria of validity-analytic definitions - for logic-mathematical statements. He holds that language can be formally considered apart from its concrete meaning. That is to create a kind of formal language in which symbols have no meaning. We can define the relation of meanings and especially the truth of logic-mathematic statements by just examining the kinds and sequences of symbols (i.e., syntactic rules). This is the criteria of validity which analytical definition develops. However, Carnapdeparts from the syntactic rules at last-the acceptance of indefinite concepts made him use themethod of valuation of semantics. Tarski's definition of truth made him believe that only semantics is what he is after. Logic truth is a concept of semantics, and only in the realm of semantics can it be given properly. The definition he gives is that "holds in every state-description". In semantics meaning is analyzed into extension and intension. The extension and intension of various descriptions can be defined by a series of L-concepts. So what is in his mind is semantics of extension, and the method of extension and intension is the basic method of his semantics.Carnap's meaning theory is a great contribution to logic, and has positive effect on the development of philosophy. The method of logical syntax which he developed signed a new phase of the study of formal language. The knowledge of Logic truth is extended by the definition of the concept of analyticity. Meanwhile, seeing all philosophical questions as those of logical syntax completed the linguistic turn in the development of philosophy. The method of intension-extension that was put forward at his latest development of thoughts is the first formal description of intension in the history of logic. He laid a semantic basis for modal logic and ushered in a new era in the development of semantics and modal logic.