Thesis: The source of all truth is the triune God revealed in the Holy Bible.
Q: Does Presuppositionalism assert that one should just accept this premise without any justification?
A: No.
Presuppositionalism asserts that all factual claims and premises must be justified, but that the ultimate justification for any claim must inevitably be a transcendent, self-justifying premise (a presupposition). Otherwise, any justification that is given must either be viciously circular or an infinite regression. One cannot defend any claim without having a foundational starting point as to what makes an argument valid.
Presuppositionalism further asserts that the only sufficient basis for an ultimate, self-justifying starting point is the author of truth. This does not mean that one must simply jump to this presupposition and immediately use it as the sole basis for all arguments. It means that any other foundation will ultimately be insufficient to justify the conclusion. The Christian apologist must “connect the dots” to demonstrate that a) all arguments are based on a presupposition, and that b) the only presupposition that can support true knowledge is a relational God who communicates and equips his creation with the knowledge of truth rooted in his character.
Christian Presuppositionalism recognizes that everyone bases their beliefs on some ultimate presupposition, and it asks the question: can your presupposition be justified? Why should the laws of logic be the basis by which an argument is justified? Where do the laws of logic come from? Why should we rely upon reason and evidence? On what basis are we able to assess whether or not an argument is “reasonable” or whether or not evidence that is offered is “true”? All of these questions must lead to a self-justifying source of truth. That source of truth must be personal (not an impersonal “force” or “idea”) in order to communicate truth to intelligent beings. The truth communicated by this personal being (God) must also be rooted in his character. In order for truth to have meaning, it must not be arbitrary or depend on some other source outside of God. If something is arbitrary it is without justification. If God obtains or assesses truth from some standard outside himself, then that source must be justified, and we have not yet arrived at a solid foundation for the existence of truth. The only justification for knowledge of truth is the self-justifying revelation of God’s character, and the only revelation that satisfies the “preconditions of intelligibility” is the revelation of the triune Christian God found in the Holy Bible. Presuppositionalism uses logic, reason, evidence, and various forms of argumentation to demonstrate that these [legitimate] forms of argumentation can only be justified by relying on the self-justifying truth found in God and revealed by Him.