Augustine and Aquinas are credited with this argument but Gordon Clark gives a modern version of it (I am referencing and summarizing this argument from Life’s Ultimate Questions by Ronald Nash here, pp. 296-297).
Some features of the world demand a personal explanation. There appear to be two categories of explanation. Some things are explained scientifically: the formation of frost on my window on especially cold mornings. This effect is sufficiently explained by “causes, conditions and the relevant laws.” In addition, some effects demand a personal explanation, where “phenomena are explained in terms of a rational agent’s intenitonal action.” For example, we could explain a death by scientific means, the knife severing blood vessel and the loss of blood from the body. But the presence of the knife demands a personal explanation – you have to explain the presence of the knife in terms of some human’s intentional behavior.
Some universal things demand more than scientific explanation, truth for instance. Truth cannot be explained scientifically, rather it is the goal of scientific endeavor, but it exists outside of the boundaries of science. So the argument for truth goes like this:
- Truth exists
- Truth is immutable
- Truth is eternal
- Truth is mental
- Truth is superior to the human mind
- Truth is God
Truth exists: If there is knowledge, there must exist the object of knowledge, that is truth.
Truth is immutable: “It is impossible for truth to change.” If it is true, it is true today, and was true yesterday, and cannot change tomorrow to falsehood. (Not what we believe to be true, rather truth itself. What we believe to be true may not in fact be true and therefore could change).
Truth is eternal: Truth will exist even if every created thing were to cease existing. Even if you postulated that someday truth will cease to exist, then it would still be true that ceased to exist. Sounds like double talk I know…
Truth is mental: “The existence of truth presupposes the existence of minds. `Without a mind, truth could not exist. The object of knowledge is a proposition, a meaning, a significance; it is a thought'” The argument here with materialists would be whether or not the thoughts are merely mechanical necessities or something more. The consciousness is an effect as opposed to a cause for the materialist. Herein lies the current tension between materialist and non-materialists. So Clark makes this statement: “bodily changes can be neither true nor false. One set of physical motions cannot be truer than others. Therefore, if there is no mind, there can be no truth; and if there is no truth, materialism cannot be true.”
Truth is superior to the human mind: Truth cannot be subjective or individualistic. Truth is immutable and eternal, and we are changeable and finite, truth judges our reason and it doesn’t vary from person to person. Truth transcends human reason, we use reason to reach truth. “Therefore, truth must transcend human reason; truth must be superior to any individual humna mind as well as to the sum total of human minds. From this it follows that there must be a mind higher than the human mind in which truth resides.”
Truth is God: Here the whole quote is worth reproducing:
“There must be an ontological ground for truth. But the ground of truth cannot be anything perishable or contingent. Since truth is eternal and immutable, it must exist in an eternal and immutable Mind. And since only God possesses these attributes, God must be truth. Is all this any more than the assertion that there is an eternal, immutable Mind, a supreme Reason, a personal living God? The truths or propositions that may be known are the thought of God, the eternal thoughts of God.”