I’ve been thinking lately about presuppositional apologetics, following (among other things) this post on Aron Ra’s blog. I’ve got the beginnings of an approach to addressing presuppositionalism, and just for fun I thought I’d throw out what I’ve got and see what kind of comments it gets. My approach is a bit Pascalesque [EDIT: Cartesian?]: I start with the premise that there is one presupposition we all share (necessarily so) and at least one fact about which we are each absolutely infallible. From these I believe we can build a rational system which will allow us to examine any other presuppositions we might make, and evaluate which of these, if any, are more likely to be correct than the others.
The presupposition we all necessarily share is that truth is consistent with itself. This means two things: first of all, negatively, truth does not contradict truth, i.e. that which contradicts truth is by definition false. Secondly and more positively, truth implies truth, i.e. discovering one truth opens up opportunities to discover more truth. Truth does not exist in isolation from other truth, but is interconnected and cohesive, enabling us to reason from a set of facts we already know to a set of conclusions we did not yet know or were not yet sure about.
The self-consistency of truth is a presupposition we all must necessarily share, or our attempt to discover the truth will be futile: we’ll be unable to distinguish what’s true from what is not, and unable to reason from any evidence to any reliable conclusion. If a believer wishes to deny that truth is consistent with itself, they’re certainly free to do so, however they must recognize that in so doing, they’re effectively conceding that atheism may be the truth after all. Sure, you may think the Bible contradicts atheism, and you may believe that the Bible is the truth, but without the principle that truth can’t contradict truth, you have no reasonable basis for rejecting atheism, even if it does contradict what you say is true.
As for personal infallibility, the one thing about which we cannot be mistaken is the fact that we exist. (Yes, Pascal René, I see you waving over there.) I know that I exist, and there is no way my knowledge could be a mistake, because if I did not, in fact, exist, then who is making the mistake? If we suppose that the giant Pokemon Snorlax is fast asleep, and is dreaming that I exist when I really don’t, then yes, that mistake could be made. But that’s not Snorlax being mistaken about his own existence, that’s a mistake regarding the existence of a third party—me. But in the first person, we cannot make that mistake. Each of us can know infallibly that we do exist, and that’s important, because truth is consistent with itself, which means that we can proceed from one truth that we do possess to the discovery of additional aspects of truth that we do not (yet) possess.
That’s as far as I’m ready to go at this point, but I think it’s an approach with some interesting possibilities, and with particular applicability to presuppositional apologetics. Your comments and discussion are welcome.