Dark Lord, you're a lot smarter than I...did I misundestand VanTil?
Van Til recognized presuppositionalism is circular in nature and since Christianity finds it authority in revealed religion, presuppositions, our basis is circular. For a better definition read Van Til who marks a difference between Christian reasoning and pagan reasoning.
"...false circular reasoning stands over against true circular reasoning.” – Cornelius Van Til, Christianity in Conflict, Chapter 9
"To admit one’s own presuppositions and to point out the presuppositions of others is therefore to maintain that all reasoning is, in the nature of the case, circular reasoning. The starting-point, the method, and the conclusion are always involved in one another.” – Cornelius Van Til, Apologetics, Chapter 4 The Problem of Method
"And this brings up the point of circular reasoning. The charge is constantly made that if matters stand thus with Christianity, it has written its own death warrant as far as intelligent men are concerned. Who wishes to make such a simple blunder in elementary logic, as to say that we believe something to be true because it is in the Bible? Our answer to this is briefly that we prefer to reason in a circle to not reasoning at all. We hold it to be true that circular reasoning is the only reasoning that is possible to finite man. The method of implication as outlined above is circular reasoning. Or we may call it spiral reasoning. We must go round and round a thing to see more of its dimensions and to know more about it, in general, unless we are larger than that which we are investigating. Unless we are larger than God we cannot reason about him any other way, than by a transcendental or circular argument. The refusal to admit the necessity of circular reasoning is itself an evident token of opposition to Christianity. Reasoning in a vicious circle is the only alternative to reasoning in a circle as discussed above.” – Cornelius Van Til, A Survey of Christian Epistemology, Chapter 1, 11 Transcendental