 Two related constraints confront the development of the perceptual model and may threaten the particularism the model is taken to support. The first is that the model must extend to prospective and hypothetical cases. Particularists and generalists typically agree that we sometimes have knowledge that if we were to perform an action (say maintain a confidence) in our actual circumstances, that action would be right. This seems essential if moral knowledge is to precede and guide virtuous conduct. Similarly, if slightly more controversially, we sometimes have knowledge that a certain course of conduct would be right in some hypothetical circumstance. While one might try to account for such cases by appeal to inductive reasoning from past actual cases, this is not, in fact, how proponents of the perceptual model have proceeded. The second constraint arises from the fact that moral properties are grounded in other properties. For example, it barely makes sense to say that an action’s wrongness is a brute fact about it; if wrong an action must be wrong on account of some otherwise specifiable features it has. While this “because constraint” admits of various explications, the basic idea is common ground and widely thought to be a priori (Zangwill 2006).