tanding project. Second, it demonstrates that genuinely novel approaches to ability remain available, and the project of giving a theory of ability may yet be in its early stages.
Thus far our questions about abilities have been formal ones: we have been asking what it is to have an ability without concerning ourselves with the substantive work that a theory of ability might have to do. But there is much work to be had for a theory of ability: abilities have figured as unexplained explainers in a range of philosophical theories, for example in accounts of concepts (Millikan 2000), of knowledge (Greco 2009, Sosa 2007), and of ‘knowing what it’s like’ (Lewis 1988). Perhaps the most prominent substantive role for a theory of ability has been the uses to which accounts of ability have been put in the free will debates. So let us close with a brief survey of what work a theory of ability might be expected to do in those debates.
Questions about abilities have figured most prominently in debates over compatibilism. ‘Compatibilism’ is used in many ways, but let us understand it here as the thesis that the ability to perform actions one does not perform is compossible with the truth of determinism, which we may take to be the view that the facts about the past and the laws jointly determine the facts about the present and all future moments. (We should sharply distinguish this view, which we might call classical compatibilism, from more recent views such as the ‘semi-compatibilism’ of Fischer and Ravizza 1998). Insofar as compatibilism, so understood, has been explicitly defended, these defenses have made appeal to theories of ability, notably the conditional analysis and its variants, as well as the dispositionalist analysis favored by the new dispositionalists.
In the discussion of the conditional analysis, we distinguished between global and local counterexamples to hypothetical theories of ability, where the former appealed to the fact that any such theory would render ability compatible with determinism which, according to the objector, it is not. There we noted the dialectical limitations of such counterexamples, namely the contentiousness of their main premise. But compatibilists have often been guilty of what seems to be the opposite mistake. Namely, they have offered theories of ability which show abilities to be compatible with determinism, and have argued from this to the claim that such abilities are indeed compatible with determinism.
The shortcomings of this strategy are nicely diagnosed by Peter van Inwagen. After surveying the local counterexamples that arise for various hypothetical theories of ability, van Inwagen imagines that we have arrived at the best possible hypothetical theory of ability, which he labels ‘the Analysis’. van Inwagen then writes:
What does the Analysis do for us? How does it affect our understanding of the Compatibility Problem? It does very little for us, so far as I can see, unless we have some reason to think it is correct. Many compatibilists seem to think that they need only present a conditional analysis of ability, defend it against, or modify it in the face of, such counter-examples as may arise, and that they have thereby done what is necessary to defend compatibilism. That is not how I see it. The particular analysis of ability that a compatibilist presents is, as I see it, simply one of his premisses; his central premiss, in fact. And premisses need to be defended. (van Inwagen 1983, 121)
van Inwagen’s point is that, provided the incompatibilist has offered arguments for the claim that such abilities are incompatible with determinism—as, in van Inwagen’s presentation, the incompatibilist has—the production of an analysis is as yet no answer to those arguments. For those arguments are also arguments, inter alia, against the compatibilist’s favored account of ability.
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 