So I am a presuppositionalist. That’s true enough, but what do I need to presuppose? This will require more development, but what needs to be presupposed is the way things actually are. You don’t need to know all the precise details of how things actually are — you don’t begin at the end — but you do have to be committed to the truth a priori, knowing that such objective, unmovable truth, which is so necessary as the foundation of every form of knowing, is not possible apart from the bedrock of the true and living God.
The fear of the Lord is the beginning of knowledge (Prov. 9:10). But beginning with the fear of the Lord does not mean beginning with the Lord alone, the Lord solitary, the Lord isolated. No one can know the Lord that way — it is incoherent — oxymoronic. God cannot be known from outside God unless there is a creation, in which the knower lives. And if he lives in a created order larger than himself, then he also knows things other than God simultaneously with his self-knowledge, and these other things also testify to the majesty of the God who created them all.
So prior to the creation, there was no fear of God. In order to have the fear of the Lord (which is the beginning of knowledge), it is necessary to have a knowing subject who does the fearing, and who knows himself to exist as a fearing creature. Moreover, he lives and moves and has his being in a world within which that fear makes sense.
That fear makes sense to the creature because he presupposes the whole shebang. He presupposes the God who is, the world that this God spoke by the word of His power, the holy law that our first parents disregarded, and the Scriptures which declare to us His spelled out explanations of all that has come to pass.
If I presuppose a Creator, then heaven and earth must be contained within that presupposition. If I presuppose a Savior, then a Word containing gospel is contained within that presupposition. If we say that God wrote two books, His Word and the world, it makes no sense to pit those books against each other. God is perfect, and the books He wrote need to be perfectly harmonious.
Not only can I not consider God independently of the created order, I cannot successfully isolate His Word to us from that created order. In order to read a Bible, I have to reckon with a cascading series of things like learning to read, a cow that contributes leather for the cover, paper, ink, the light that strikes the page, the physical eyes that receive that light, the brain cells that remember what I read yesterday, and so on. How shall they distribute tracts without a typesetter?
It is not the case that the world comes to me through this portal, and the Word through that portal. God is the living constant, and He is speaking at all times and through all things. This is something precious I learned from Van Til. At the same time, I do want to run with some of this and apply it in ways that perhaps Van Til would have been uncomfortable with. The computer that is my brain can (I think) run two operating systems — Van Til 1.2. and Lewis 5.2. The code in the back room can look pretty funky sometimes, but I like the way it looks on the screen.
So, like all presuppositionalists, I try to reason from Scripture instead of reasoning my way to the Scriptures. I don’t want to presuppose a neutral space, from which I try to get others to become Christian. But when I presuppose Scripture, there is another foundational layer underneath that. I must presuppose a God who is absolute, and who has revealed Himself in absolutely everything. In the words of Schaeffer’s great title — He is there, and He is not silent.