 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).