Abstract

A radical metaphysical theory typically comes packaged with a semantic theory that reconciles those radical claims with common sense. The metaphysical theory says what things exist and what their natures are, while the semantic theory specifies, in terms of these things, how we are to interpret everyday language. Thus may we “think with the learned, and speak with the vulgar.” This semantic accommodation of common sense, however, can end up undermining the very theory it is designed to protect. This paper is a case study, showing in detail how one popular version of temporal parts theory is self-undermining. This raises the specter that the problem generalizes to other metaphysical theories.