In the accounts we give of one another, claims about our abilities appear to be indispensable. Some abilities are so widespread that many who have them take them for granted, such as the ability to walk, or to write one’s name, or to tell a hawk from a handsaw. Others are comparatively rare and notable, such as the ability to hit a Major League fastball, or to compose a symphony, or to tell an elm from a beech. In either case, however, when we ascribe such abilities to one another we have the impression that we are making claims that, whether they are worth saying or not, are at least sometimes true. The impression of truth exerts pressure towards giving a philosophical theory of ability.