 As to 14, the idea is that the direction of priority must be a necessary truth, at least with respect to all metaphysically possible worlds. It would be odd if there were worlds that were otherwise indiscernible, save for differing over what was prior to what. The direction of priority seems to have the same status as other fundamental metaphysical claims (e.g., the debate over  universals).[44]  To know the direction of priority seems to be part of what Rosen (2006: 35) has in mind when he speaks of knowing: