 We have here, then, a point at which Austin expresses his view that ordinary attributions of ability, power, and capacity are incompatible with the thesis of determinism. In response, the compatibilist is forced, I think, to deny that its being true that a golfer could have holed the putt, or even that he could have holed the putt in precisely the same conditions, entails that he would have holed the putt in a perfect duplicate of the actual world. Leaving that issue to one side, Austin presents the proposed analysis with a case of masking—a case in which, although ability is retained, successful exercise of the ability is somehow precluded, for instance by outside interference (for discussion of masking, see A. Bird 1998; Clarke 2009; Fara 2008; and Johnston 1992). The challenge facing the defender of the analysis is to spell out the analysis so as to cope with masking. Arguably, meeting the challenge depends upon provision of a non-circular specification of all possible masks. Austin would, I think, claim that it is impossible to meet the challenge. For on his view, abilities are sometimes masked brutely, without any specifiable mask. Even if he is wrong about that, it remains an open question whether the challenge can be met, or whether the endless heterogeneity of potential masks makes it impossible to provide an explanatory specification.