“By his hatred of God the natural man is bound to repress the truth of revelation given him. He does not want to be confronted with the demands of the God against whom, ever since the day of Adam at the beginning of history, he is in rebellion. Even in the field of philosophy this opposition to God appears. Everywhere, in man’s own constitution as well as in his environment, God speaks to man. But everywhere too man the sinner, seeks to suppress the truth about himself and his relation to God his creator. Even when God in his grace speaks redemptively to man through Christ, and then Christ speaks redemptively to man through the Scriptures, the natural man again seeks to repress this revelation. He uses his scientific and philosophic as well as his theological systems in order to keep under the challenge of the revelation of God to him. Everywhere God meets man and everywhere asks man to answer. Man is inherently a covenantal being. He is one who cannot help but answer to God. He can give the right answer to God only through Christ’s atoning blood and through the regenerating power of the Holy Spirit. Once Christ has become a curse for him on the cross, and once Christ has risen from the dead for his righteousness and he has by the Spirit’s power accepted this salvation wrought for him in history, then he seeks at every point to be a covenant-keeper. He then seeks to be a covenant-keeper in the field of science and philosophy no less than in the field of theology. The great presupposition of all his efforts at interpreting himself and the world about him is the fact that he and the world are first interpreted by God in Christ as revealed in Scripture.
On this basis human self-awareness is awareness of self in relation to what God has revealed himself as being for man through Christ. On this basis God speaks to man from above and man answers to God as a scientist, as a philosopher and as a theologian. All his predication constitutes one great answer of covenant gratitude to his redeemer through whom he has been brought back to God the father.”
Cornelius Van Til
Christianity & Barthianism – p. 432
This provides a succinct explanation by CVT on presuppositionalism. In the explanation of it we see why Thomistic Natural Law theories are not and can not be true. Man as fallen, is out of covenant with God and as out of covenant with God fallen man seeks to interpret all reality in relation to himself as the prime epistemological authority. Man, as it were, takes himself as God and seeks to interpret all reality is light of his own legislative word. As such, fallen man, necessarily interprets the totality of reality amis.
That fallen man, necessarily interprets the totality of reality amis does not mean that fallen man does not manage to get some micro matters of reality aright but when he does get some micro matters of reality aright it is always in service of his worldview that is determined that “we shall not have this God rule over us.” At those points when fallen man gets micro matters aright in service of his rebellion against God and His reality fallen man can never account for how it is he was able to get micro matters aright. As Dr. Greg Bahnsen was fond of saying; “Fallen men can count but they cannot account for how it is they can count.” It should be noted though that over the course of time as the anti-thesis works itself out in history fallen man get fewer and fewer matters touching reality right. For example, fallen man in the West pretty much once understood that boys were boys and girls were girls but as time has passed and as the anti-thesis has developed now there is uncertainty about the answer to the question; “What is a woman.”
Fallen man, then, will use stolen capital from God’s reality to get his denial of God’s reality off the ground and flying. This is necessary to fallen man because there is no way to have a perfectly God hating worldview and still remain alive, for a perfectly God hating worldview is the worldview of a graveyard. It is at the point of stolen capital that the apologist must challenge fallen man. For example, natural law has stolen capital from God’s worldview by saying that man is a knower. Fallen man is indeed a knower however what Natural Law does not take into consideration is that fallen man as a knower is committed, a-priori, to not knowing the one reality that would make fallen man a knowing knower. Natural law admits that all ground is common ground but it refuses to acknowledge that no ground is neutral ground and it refuses to admit that fallen man is not neutral to the matter of knowing. Knowing man may be a sharp blade but he is a sharp blade that cuts at the wrong angle every time.