It is shown that there is an unconditional requirement on rational beings to adopt “reflexive” beliefs, these being beliefs with a very particular sort of self-referential structure. It is shown that whoever adopts such beliefs will thereby adopt beliefs that imply that a certain proposition, &PSgr;, is true. From the fact that there is this unconditional requirement on rational being to adopt beliefs that imply &PSgr;, it is concluded that &PSgr; is knowable a priori. &PSgr; is a proposition that says, in effect, that one’s own point of view is a point in space and time that is the point of view of some being who has reflexive beliefs. It is argued that this information that is contained in &PSgr; boils down to the information that one’s point of view is located at a point in the world at which there is something that is “conscious” in a certain natural and philosophically interesting sense of that word. In other words, a theory of consciousness is defended according to which an entity is conscious if and only if it has reflexive beliefs.