Abstract

So far I have said nothing about the Principle of Verification, the most distinctive claim of the positivists. In the volume Carnap traces the development of his views from narrow to more liberalized versions of empiricism. During the 1920's, holding that the meaning of a statement is given by the conditions of its verification, and that a statement is meaningful if and only if it is in principle verifiable, he declared many theses of traditional metaphysics to be meaningless. In Der Logische Aufbau der Welt he defended a phenomenalist thesis according to which cognitively meaningful statements could be translated into a language referring only to total moments of experience. Later he espoused physicalism, the claim that cognitively meaningful statements are translatable into statements concerning observable properties of physical things. In "Testability and Meaning", recognizing that statements about "theoretical" entities in science can never be completely translated into observational terms, Carnap liberalized his empiricism by requiring for cognitive meaning not translation into observational terms, but only the possibility of confirmation on the basis of observation. What I propose to consider here are Carnap's latest thoughts on these issues as expressed in his Introduction and Replies and in recent articles.