ween a theory of ability and the free will debates. Such debates often involve claims about agents’ abilities, and many have hoped that getting clearer on abilities themselves could resolve, or at least shed light on, such debates. The aim of this last section will be to assess whether these hopes are reasonable ones.
- 1. A taxonomy
- 2. Two fundamental distinctions
- 3. Hypothetical theories of ability
- 4. Modal theories of ability
- 5. New approaches to ability
- 6. Abilities and the free will debates
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What is an ability? On one reading, this question is a demand for a theory of ability of the sort described above. On another reading, however, this question simply asks for a rough guide to what sort of things we are speaking of when we speak of ‘abilities’. So understood, this question is not asking for a theory of ability, but for an explanation of what exactly a theory of ability would be a theory of. This section will offer an answer to this question on this second, more modest, reading.
It will be helpful to begin by considering a topic that is related to, but nominally distinct from, abilities: dispositions.
Dispositions are, at first pass, those properties picked out by predicates like ‘is fragile’ or ‘is soluble’, or alternatively by sentences of the form ‘x is disposed to break when struck’ or ‘x is disposed to dissolve when placed in water.’ Dispositions so understood have figured centrally in the metaphysics and philosophy of science of the last century (Carnap 1936 & 1937, Goodman 1954), and also in influential accounts of the mind (Ryle 1949). They are like abilities in many significant respects, in particular in the fact that they are properties of things that can exist even when not manifested: as a glass may be fragile even when it is not broken, so may a person have the ability to raise her arm even when she is not raising her arm.
While dispositions have been central to contemporary philosophical discussions, they do not exhaust the range of the possibilities inherent in things. Especially notable, for present purposes, are those that are intimately connected to agency. These include the susceptibility of things to be acted on in certain ways — such as the edibility of an apple, or the walkability of a trail — that the psychologist J.J. Gibson called affordances (Gibson, 1979). These include also the powers of action that we ascribe to things, of the kind observed by Thomas Reid: ‘Thus we say, the wind blows, the sea rages, the sun rises and sets, bodies gravitate and move’ (Reid 1788/2010, 16; Reid himself regarded these locutions as "misapplications" of active verbs, based on erroneous views of the grounds of powers). Finally, and crucially, these include the powers of agents themselves.
In light of this ontological diversity, it will be useful to have a term that encompasses all the possibilities inherent in things and in agents. Let us reserve the word ‘power’ for that general class. Dispositions, as defined above, are a proper subset of powers more generally. Affordances, as sketched above, are another one. And abilities, in a sense still to be defined, are yet another.
It may yet be that dispositions are especially privileged among the powers. For instance, they might be more fundamental than the other powers, in the sense that other powers may be reduced to them. It has been proposed, for instance, that affordances may be reduced to dispositions (Scarantino 2003). And we will consider in some detail, in Section 5.1, the proposal that abilities themselves may be reduced to dispositions. But our initial hypothesis is that dispositions are simply one member of the broader family of powers, albeit one that has received a great measure of attention in the philosophical literature.
Abilities, then, are a kind of power. What kind of power, precisely, is an ability? As the term will be understood here, there are two additional conditions that a power must meet in order for it to be an ability. First, abilities are distinguished by their subj