Temporally Conditioned Descriptions and the Concept of Temporal Purity

Abstract

It is a commonplace fact that an event, state of affairs, or object is never to be described only by means of some one single and unique description: there must inevitably be a multiplicity of distinct descriptions (both definite and indefinite descriptions) which describe or single out the same thing. Given a pair of definite descriptions D₁ and D₂ such that what is referred to by the description D₁ — the descriptum of D₁ — is the same as or identical with the descriptum of D₂, it is well known that such an inference as the following fails:

Smith believes that —D₁—; therefore

Smith believes that —D₂—.