Presuppositionalism is a school of Christian apologetics that believes the Christian faith is the only basis for rational thought. It presupposes that the Bible is divine revelation and attempts to expose flaws in other worldviews. It claims that apart from presuppositions, one could not make sense of any human experience, and there can be no set of neutral assumptions from which to reason with a non-Christian. Presuppositionalists claim that a Christian cannot consistently declare their belief in the necessary existence of the God of the Bible and simultaneously argue on the basis of a different set of assumptions that God may not exist and Biblical revelation may not be true. Two schools of presuppositionalism exist, based on the different teachings of Cornelius Van Til and Gordon Haddon Clark. Presuppositionalism contrasts with classical apologetics and evidential apologetics.
Presuppositionalists compare their presupposition against other ultimate standards such as reason, empirical experience, and subjective feeling, claiming presupposition in this context is:
a belief that takes precedence over another and therefore serves as a criterion for another. An ultimate presupposition is a belief over which no other takes precedence. For a Christian, the content of Scripture must serve as his ultimate presupposition… This doctrine is merely the outworking of the lordship of God in the area of human thought. It merely applies the doctrine of scriptural infallibility to the realm of knowing.
Critics of presuppositional apologetics claim that it is logically invalid because it begs the question of the truth of Christianity and the non-truth of other worldviews.