  According to the standard account, a self-evident proposition is one which an adequate understanding of the proposition justifies us in believing it. But all that Locke and Price say is that we need an understanding of a self-evident proposition in order to believe it, and presumably to be justified in believing it. They do not say that our understanding provides that justification, or that when we believe it, we believe it on the basis of our understanding. Indeed the idea that it is our understanding of a self-evident proposition that justifies us in believing it may sound odd to many people. Certainly if one assumes that if p justifies belief in q, then p is a reason to believe q, it is hard to see how our understanding justifies us in believing the proposition understood, for no one can claim that their understanding of a proposition gives them a reason to believe it. One explanation of this is that the sort of thing that can provide reasons to believe that p are either evidence that p or, more controversially, pragmatic considerations, such as that believing that p will have certain good consequences. An adequate understanding of a proposition is neither of these things. The fact that I understand some proposition is not something that would make believing that proposition have any good consequences, and my understanding is not evidence for the truth of the proposition understood. Evidence is standardly understood as something that makes the proposition it is evidence for more probable. But an adequate understanding of a proposition does not make that proposition more probable, so is not evidence for it. Since an understanding of a proposition is neither a pragmatic nor an evidential consideration, it seems it is not the right sort of thing to give us a reason to believe that proposition, and so not the right sort of thing to justify that belief. Robert Audi has, however, recently offered an account of adequate understanding that attempts to deal with this kind of objection. He does not claim that adequate understanding of a proposition is evidence for that proposition, but claims that adequate understanding puts us in touch with the truth-makers of the self-evident proposition, and it is this that makes it the right sort of thing to justify belief (Audi, 2019, 379–380) 