Godís Self-Contained Knowledge.
In contrast to this [the idea that the law of contradiction operates the same in both God and man], Christianity holds that God existed alone before any time existence was brought forth. He existed as the self-conscious and self-consistent being.† The law of contradiction, therefore, as we know it, is but the expression on a created level of the internal coherence of Godís nature. Christians should therefore never appeal to the law of contradiction as something that, as such, determines what can or cannot be true. Parmenides serves as a warning of what happens to history if the law of contradiction is in this fashion made the ultimate standard of appeal in human thought.† Parmenides concluded that to understand anything historical, it would have to be reduced to an element in a timeless system of categories. He therefore denied the reality and significance of all historical plurality. In modern times it is customary to use the law of contradiction negatively rather than positively as Parmenides did. On the surface this appears to leave room for historical factuality. But it does so only if this historical factuality be thought of as being unknowable or irrational.
Christians should employ the law of contradiction, whether positively or negatively, as a means by which to systematize the facts of revelation, whether these facts are found in the universe at large or in the Scripture. The law of contradiction cannot be thought of as operating anywhere except against the background of the nature of God.† Since, therefore, God created this world, it would be impossible that this created world should ever furnish an element of reality on a par with him. The concept of creation as entertained by Christians makes the idealist notion of logic once for all impossible. The creation doctrine is implied in the God-concept of Christianity; deny the creation doctrine and you have denied the Christian concept of God. A created being or a created reality in general cannot furnish a novelty element that is to stand on a par with the element of permanency furnished by the Creator.† If one believes in the creation doctrine at all, one has to say that the novelty element of the universe is subordinate to the eternal plan of God.† Christians believe in two levels of existence, the level of God's existence as self-contained and the level of man's existence as derived from the level of God's existence. For this reason, Christians must also believe in two levels of knowledge, the level of God's knowledge which is absolutely comprehensive and self-contained, and the level of man's knowledge which is not comprehensive but is derivative and re-interpretative. Hence we say that as Christians we believe that man's knowledge is analogical of God's knowledge.
Cornelius Van Til, from An Introduction to Systematic Theology, p. 11.† Class Syllabus, 1966. WTS