 Laurence BonJour thinks that a rational insight is an immediate, non-inferential grasp, apprehension, or “seeing” that some proposition is necessarily true (BonJour 1998: 106). He goes on to argue that a proposition’s appearing to be necessarily true is the foundation of a priori justification, because he wants to allow that such justification can be fallible and defeasible. So for BonJour it is apparent rational insights that are the evidence on which a priori justification rests, not rational insights themselves (1998: 112–113, 1998: §§4.5, 4.6). After publishing In Defense of Pure Reason (1998), and in response to comments by Paul Boghossian (2001), BonJour wrote that these appearances are not propositional, that is, they are not appearances that something is the case (BonJour 2001a: 677–678). In this respect, they are unlike beliefs and more like perceptual sensations.