General-term rigidity is meaning constancy

Abstract

It is often thought that some general terms or kind terms, in particular natural kind terms, are rigid designators, and that a properly extended notion of singular-term rigidity can help explain the behaviour of such general terms. In this article, I argue that the only legitimate notion of general-term rigidity is a trivial one and identify some crucial asymmetries between a posteriori necessary truths involving names and a posteriori necessary truths involving general terms. If we pay attention to these asymmetries, it becomes clear that attempts to draw a non-trivial rigid/non-rigid distinction for general terms are bound to fail to offer the explanations we expected. As opposed to singular terms, what is interesting about the behaviour of natural kind terms, even in modal contexts, cannot be accounted for by modal distinctions like rigidity/non-rigidity but must rather track non-modal features.