 There are, then, several obstacles for the compatibilist who wishes to appeal to an account of ability in defense of compatibilism. First, there is the general difficulty of actually giving an extensionally adequate theory of ability. In addition, we have now turned up a couple of more specific challenges to the compatibilist. There is van Inwagen’s point just outlined, namely that arguments for the incompatibility of abilities and determinism are, inter alia, arguments against any theory of ability that is congenial to the compatibilist. And, finally, there is the point that we encountered in our discussion of the new dispositionalism in Section 5.1, which is that certain platitudes about ability — in particular, those involved in certain judgments about moral responsibility — may be recalcitrant to compatibilist treatments. Taken together, these points seem to pose a serious obstacle to any theory of ability that is both compatible with determinism and in accord with our ordinary judgments about what ability requires.