Each claims that his position is “in accord with the demands of logic.”
a. The Christian claims this because he interprets the reach of logic as manipulated by man, in terms of God’s revelation of the relation of man to the world and therefore in terms of his presupposition of God. Genesis tells him that nature is made subject to man, and both are subject to God and his purpose. Thus his logic is in gear with reality, but it does not claim to control God himself and therewith all possibility.
b. The non-Christian claims that his position is logical but cannot put any intelligible meaning into the claim. If he works according to his presupposition about the ultimate non-rationality of facts, then all logic operates in a void. It has no contact with the world. If he works according to his presupposition of the ultimacy of all facts, then all facts are reduced to logic and thereby destroyed because they lose their individuality; logic has a validity that is, therefore, purely formal. It could only be a logic of identity, merely saying A is A, for all would be one.
– Cornelius Van Til, The Reformed Pastor and Modern Thought.
(Variations in The Defense of the Faith p.305, and Jerusalem and Athens p.20)