 This account has two particular merits. First, it is much closer to the way scientists understand and use theoretical terms than purely causal accounts. Because of this, it is not only an account of reference but also one of meaning for theoretical terms. In purely causal accounts, by contrast, there is a tendency to abandon the notion of meaning altogether. Second, it promises to ensure a more stable notion of reference than in purely descriptivist accounts of reference and meaning. Notably, the kind of causation that Psillos’s hybrid account refers to is different from the causal-historical chains that Kripke thought responsible for the transmission of reference among speakers. No further explanation, however, is given of what a kind-constitutive property is and how we are to recognize such a property. Psillos (1999: 288n) merely infers the existence of such properties from the assumption of there being natural kinds.