Naturally, Plato was “helpful” when he pointed out to the Sophists that, if reality were subject to universal flux, then human predication would cease to have meaning, and that relativistic theories were generally proposed with a claim of absolute truthfulness. But then, having said this, it would have been well to investigate the other half, namely, that the Sophists were, of course, equally capable of refuting Plato. His highest law, the absolute universal, was a purely empty form. Whatever else was to be said of it, it had still to be made correlative to the idea of pure contingency. But by merely speaking, Plato became a relativist; thus, he took pure contingency into his pure absolute. As with the Sophists, he had to, if he spoke at all, contradict himself with every word. For appearances of justification in predicating on any subject, it thus behooved the Platonist and the Sophist to take in each other’s washing. Pure form and pure “matter,” or pure contingency, are correlatives of each other. Possibly, Christians throughout history would have an emotional preference for the idealist thinking of Platonism, as over against all forms of sophism, as well as mechanism, materialism and pragmatism before or since. But, as to logical priority, neither was able to “make peace with the law of contradiction,” i.e., neither one could offer a positive foundation upon which the law of contradiction might have been employed at all. Only the Christian position, with its teachings of the triune God as the creator and redeemer of men, is the true starting-point for all argument without contradiction. Scepticism is defeated only by Christianity.
– Cornelius Van Til, Who Do You Say That I Am? p.17