ard the letter of (CA), but retain its spirit. For it may be that the historical failure of (CA) is due to difficulties and oversights that our perhaps firmer grasp of technical issues allows us to overcome. This is a sensible and well-motivated project, though it remains to be seen whether it will be, in the end, a successful one.
There remain still other accounts that do not fit easily into the taxonomy provided here. These include primitivist proposals, which take ability or some closely related notion as analytically fundamental. One development of this idea is Maier 2015, who proposes, contrary to most authors, that specific ability is fundamentally prior to general ability. He argues that we should give an account of general ability in terms of specific abilities, which he calls ‘options’: roughly, an agent has the general ability to A iff she normally has A as an option. Options, in turn, are primitives. Much here will hang on saying more about options, and in what sense they figure as primitives in the theory of agency.
Finally, an outline of a proposal by David Lewis (dated to 2001 but only recently published as Lewis 2020) offers an altogether different approach to ability. Lewis is motivated, like many proponents of (CA), by the goal of defending compatibilism, but he takes (CA) to be unsatisfactory. He therefore proposes a non-conditional analysis of ability. His analysis, roughly, is that S has the ability to perform an action B just in case there is some basic action A such that (i) S’s doing A would cause or constitute S’s doing B and (ii) there is no obstacle to S’s doing A. The problem of giving a theory of ability then becomes the problem of giving a theory of obstacles, something at which Lewis, in his outline, makes a beginning. (See Beebee et al 2020 for additional discussion).
Lewis’s proposal is an inspiration for further research in at least two ways. First, it indicates that Lewis, a systematic philosopher of modality, saw the problem of giving an analysis of ability as a significant outstanding 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, accor