on is more properly philosophical. If we accept the distinction between general and specific abilities, then we want for our account of ability to accommodate both of them, and ultimately to explain how they are related to each other. For this distinction is not plausibly diagnosed as mere ambiguity; it rather marks off something like two modes of a single kind of power. There are at least two kinds of proposals one may make here. One, arguably implicit in many of the ‘new dispositionalist’ approaches to ability, is that general ability is in some sense prior to specific ability: to have a specific ability is simply to have a general ability and to meet some further constraint, such as having an opportunity. Another proposal (suggested in Maier 2015) is that specific ability is in some sense prior to general ability: to have a general ability is simply to have a specific ability under a certain range of circumstances.
The idea that there is some sort of bipartite distinction to be made between abilities has been a prominent theme in contemporary work on ability. It has been endorsed and developed, in different contexts, by Glick (2012), Vihvelin (2013), and Whittle (2010). It is an open question whether the bipartite distinctions in ability introduced by these authors are the same as one another, or the same as the one introduced here. It could be that there are several bipartite distinctions to be made in this area, or that we simply have one distinction under several names.
Much philosophical discussion of ability has taken place in the formal, as opposed to the material, mode. Thus we are often asked to distinguish senses of ‘ability’, or to think about what ‘can’ means. This subtle shift between discussing ability and discussing the ascription of ability is often harmless. Nonetheless, it is important to bear in mind the distinction between these questions, and to mark this distinction explicitly at the outset.
On the one hand, there are questions about ability itself. The central question here to give an account of what an ability is, in the sense foregrounded at the outset. Subsidiary questions here include, for example, whether abilities may exist when they are unexercised, whether abilities are intrinsic or extrinsic features of their bearers, and whether agents have abilities in deterministic worlds. These are, broadly speaking, questions about the metaphysics of ability.
On the other hand, there are questions about ability-ascriptions. Abilities are characteristically ascribed (in English) with sentences involving the modal auxiliaries ‘can’ and ‘is able to.’ Accordingly, the central question here is to give a semantics for sentences involving those expressions. Subsidiary tasks include resolving certain open problems in the semantics of these expressions, such as the ‘actuality entailment’ observed in (Bhatt 1999), and integrating a semantics for agentive modals with a semantics for modal expressions more generally. These are, broadly speaking, questions about the semantics of agentive modality.
On certain conceptions of the philosophical enterprise, the project of giving a theory of ability and that of giving a semantics for ability-ascriptions are closely connected, and even collapse into each other. Nonetheless, there is at least a methodological distinction to be marked here. Having marked that distinction, this discussion will primarily be concerned with the first of these projects, the project of giving a theory of ability. Nonetheless, the project of giving a semantics for ability-ascriptions will also frequently be relevant. As with the distinction between general and specific abilities, this is for two reasons, one of coverage and one more properly philosophical.
The first reason, that of coverage, is the following. Many of the most prominent theories of ability defended in the philosophical literature have in fact been, in the first place, theories of ability-ascriptions. Indeed, the central thought in much work on ability in the analytic tradition has been a kind of semantic deflationism, on which w