Abstract

The verifiability principle was the characteristic claim of a group of thinkers who called themselves the Vienna Circle and who formed the philosophical movement now known as logical positivism. The verifiability principle is an empiricist criterion of meaning which declares that only statements that are verifiable by —i.e., logically deducible from— observational statements are cognitively meaningful. This essay is a short introduction to the philosophical movement of logical positivism and its formulation of the verifiability principle. Its primary aim is to provide students of philosophy with an accessible first overview of this philosophical movement. After pointing out some aspects of the philosophical background of logical positivism (section 1), I will comment on the reasoning that lead these authors to formulate the verifiability principle (section 2), and I will analyse the debate about how to understand observational language and how observational statements (the so-called ‘protocol statements’) are verified (section 3). I will also comment on the two main consequences of accepting the verifiability principle: the conception of philosophy as the task of logical analysis and the project of unified science (section 4), and I will explain the different views on ethical language defended by logical positivists (section 5). I will end this essay by identifying the main problems of the verifiability principle and I will explain the core ideas of Carnap’s confirmability criterion, which attempts to resolve these problems (section 6 and 7).