Two-Dimensionalism and Natural Kind Terms

Kripke and Putnam have convinced most philosophers that we cannot do metaphysics of nature by analysing the senses of natural kind terms – simply because natural kind terms do not have senses. Neo-descriptivists, especially Frank Jackson and David Chalmers, believe that this view is mistaken. Merging classical descriptivism with a Kaplan-inspired two-dimensional framework, neo-descriptivists devise a semantics for natural kind terms that assigns natural kind terms so-called ‘primary intensions’. Since primary intensions are senses by other names, Jackson and Chalmers conclude that we can and should do metaphysics of nature by analysing the natural kind concepts competent speakers possess. I argue that neo-descriptivism does not provide a suitable basis for doing this kind of metaphysics. I first of all give a detailed account of the neodescriptivist semantics and deflate the intuitive support neo-descriptivists try to draw from their case of the XYZ-world. I then present three arguments – the Argument from Ignorance, the Argument from Conceptual Analysis, and the Argument from Laziness. Taken together, these arguments undermine the neo-descriptivist analysis of natural kind terms. I conclude that natural kind terms do not have senses, that we cannot do metaphysics of nature by analysing the senses of our kind terms, and that the Kripke-Putnam account still provides the best semantics for natural kind terms we have.