It is customary on the part of some orthodox theologians to depreciate the objects of sensation as a source of knowledge. They have become deeply convinced of the scepticism involved in historical empiricism. They would therefore substitute an a priori approach for that of the empiricist, thinking that thus they represent biblical thought.

Two points may be mentioned with respect to this. In the first place, to flee to the arms of an apriorism from those of empiricism is in itself no help at all. It is only if an a priori is self-consciously based upon the conception of the ontological Trinity rather than upon the work of Plato or some other non-Christian philosopher that it can safeguard against scepticism. The a priori of any non-Christian thinker will eventually lead to empiricism. It can keep from doing so only if it keeps within the field of purely formal predication. In the second place, if we do place the ontological Trinity at the foundation of all our predication then there is no need to fear any scepticism through the avenue of sense. Sensation does “deceive us” but so does ratiocination. We have the means for their corruption in both cases. The one without the other is meaningless. Both give us true knowledge on the right presupposition; both lead to scepticism on the wrong presupposition.

Van Til, An Introduction to Systematic Theology p.123-124