Temporal Externalism, Natural Kind Terms, and Scientifically Ignorant Communities

Abstract

Temporal externalism (TE) is the thesis (defended by Jackman (1999)) that the contents of some of an individual's thoughts and utterances at time t may be determined by linguistic developments subsequent to t. TE has received little discussion so far, Brown 2000 and Stoneham 2002 being exceptions. I defend TE by arguing that it solves several related problems concerning the extension of natural kind terms in scientifically ignorant communities. Gary Ebbs (2000) argues that no theory can reconcile our ordinary, practical judgments of sameness of extension over time with the claim that linguistic usage determines word extensions. I argue that Ebbs shows at most that no theory other than TE can effect this reconciliation. Furthermore, while Ebbs' argument undermines Jessica Brown's solutions to two closely related problems about natural kind term extensions (Brown 1998), TE can solve both problems without difficulty. Some criticisms of TE are briefly addressed as well.