 This picture raises many difficulties, and needs considerable refinement and defence. (For variations, see Velleman 1989; Velleman 2000; Setiya 2007a, Part One; Rödl 2007, Ch. 2; Setiya 2016b.) Some will resist the claim that acting for a reason is acting with self-knowledge—though it is important to stress that the knowledge attributed here need not involve conscious belief. There is also disagreement about the kind of explanation involved in giving the reasons for which one acts (Wilson 1989, Ch. 7; Ginet 1990, Ch. 6; Dancy 2000; Davis 2005; Alvarez 2010; Setiya 2011). But if the picture is basically right, it suggests that the unity of intention can be found in knowledge or belief about action. Assuming that knowledge entails belief, the basic thought is that intention in action involves the belief that one is doing A. Doing something for a reason involves a belief about one’s reason for doing it that constitutes intention in action. And prospective intention, or intention for the future, involves a belief about what one is going to do and why. The idea that intention involves belief is what unifies intentional action, prospective intention, and intention-with-which. (On an alternative view, which may be Anscombe’s, intention contrasts with belief: they correspond to radically different kinds of knowledge. See the treatment of mistakes below.)