But let's be clear here: PSR is not germaine to the question of whether or not the unbeliever is warranted in using reason or whether the reasoning process is de facto borrowed from the Christian worldview. The use of reason is self-evidently warranted. As for PSR, there has to be a point where the chain ends---our disagreement is over where. The unbeliever is simply arguing for a multiplicity of places---it's a messy position, but not (from my understanding) self-contradictory. Ok, here's where you and I are talking past each other: when I talk about a reason for a belief I am simply speaking of the reason why I believe X. You, however, are speaking of the reason why X is the case. The term doesn't make sense---that's my argument. The reason for X is Y and Y is a contingent fact. But that doesn't mean that it's relation to X is contingent---its relation to X may be necessary. It may be the de facto reason for the truth of X, but its relation to X is an open question apart from that. No, I don't believe that reasons exist---I'm not a Platonist or a Scotist. Part of the issue is this: a) Presuppositions are the foundation in the sense that they are informing principles that shape the way we think. The very term Presupposition implies that it is a basic component of one's epistemic structure. b) They aren't propositional at all, or rather their propositional forms are merely manifestations of underlying attitudes and precommitments, methodologies, and predispositions. How would one give an account of a predisposition?