Philosophical Quarterly (April 1998)
Charlie Martin has shown that the simple conditional analysis of dispositional concepts (x is disposed at time t to give response r to stimulus s) is in error. This is due to finkish dispositions which are caused to disappear by the stimulus s. David Lewis has proposed an improved analysis which takes account of finkish dispositions by requiring that the appropriate causal basis remains for a sufficiently long time. In this paper I argue that Lewis's analysis also fails. This is because of the possibility of antidotes. An antidote to a disposition interferes with its normal operation so that, although the disposition and its causal basis remain, the stimulus does not bring about the usual response. I consider several possible defences of Lewis's analysis and a plausible repair, but find these unsatisfactory. I conclude that an analysis of disposition concepts is not available because an unavoidable indexical element (e.g. reference to normal circumstances) is present in explanations of these concepts. In this regard, and others, they may be thought of as akin to theoretical or natural kind concepts.