Meta Ontology

Kripke argued, famously, that proper names are rigid designators. It is often assumed that some kind terms (most prominently natural kind terms) are rigid designators as well. This is thought to have significant theoretical consequences, such as the necessity of certain a posteriori identities involving natural kind terms. However, there is no agreement on what it is for a kind term to be rigid. In this paper I will first take a detailed look at the most common view: that rigid kind terms are those which designate the same kind in all possible worlds. This view has been subjected to much recent criticism. I will argue that, while the proponents of the view do seem to have good answers to some of the arguments presented against it, it fails because this notion of rigidity cannot deliver aposteriori necessities. Time permitting, I will also sketch an alternative view which seems far more promising