Rules of Inference: A Study in Early Analytic Philosophy.

摘要

This dissertation concerns the debate over the nature of inference in early analytic philosophy. Frege and Russell hold that inference is justified by appeal to rules of inference, and that these rules must be inexpressible in the language that they govern. In this way both Frege and Russell avoid the threat of regress which would arise if the justification of inference involved additional inferential reasoning. Even though they take the rules of inference to be inexpressible, they both think that these rules encode substantive logical content --- they form part of the foundation of their logical systems. Wittgenstein argues that this account of inference reflects a deep confusion about the nature of logic and its relation to thought. By motivating this critique, the dissertation develops a new account of Wittgenstein's philosophy of logic. According to Wittgenstein, to understand a proposition is to situate it in the logical space of commitments and permissions that articulate its relations to the other propositions that we understand. Thus when we understand the premises of an inference, we are already in a position to justify the conclusion, and there is no need for us to appeal to logical principles. Logic informs our thought, but is not part of its content. Frege and Russell fail to properly distinguish the logical form and the content of thought. On a proper understanding of Wittgenstein's conception of logic, there is no room for inexpressible but contentful rules of inference.