 Of course Prichard does not just announce that obligatoriness is not a property of acts. He has two arguments. The first is that there are epistemic difficulties in supposing that acts are made obligatory by objective matters of fact such as their own nature and the attendant circumstances. Most of these things are things that we cannot truly know to be the case, such as what results our action will have (at this point Prichard is appealing to the theory of knowledge that he inherited from Cook Wilson). If so, we would hardly ever be able to know what our duty was; and the thought that most of our duties are things of which we cannot know is unbearable. This difficulty vanishes if we suppose that the ground for duty is not the objective nature of the situation, but the way the agent supposes things to be. But if we make that move, we suppose that the ground for duty lies in some fact about the agent (that she so supposes), and this makes it much easier to think of the duty itself as attaching to the agent rather than to the act. (On this argument and its peculiarities, see Dancy, 2002.)