 Some philosophers have said that dispositions are not causes of, or causally explanatory of, their manifestations. Why? Their thought can be encapsulated by Molière famous quip, in Le Malade Imaginaire, that a philosopher might explain why opium puts people to sleep by mentioning the fact that it has a ‘dormitive virtue’. The point, of course, is that this is no explanation or, if it is, it is not a good explanation. To have a dormitive virtue, it seems, is just to have a property that puts people to sleep, and that fact tells us only a little, if anything, about why substances with that property put people to sleep. In general, \(x\)’s possession of a disposition \(D\) conceptually necessitates \(x\)’s manifesting \(D\) under a suitable condition, and conceptual necessitation is not a kind of causal or explanatory connection. This is what McKitrick (2004, 2005) names the ‘analyticity argument’ for the causal inefficacy of dispositions. Arguments of this kind have been brought forth by Mackie (1973, 1977), Armstrong (1968), Block (1990), and Jackson (1995, 1996).