“The Bible claims to be God’s Word. This is our starting point. Of course, just because a book says it’s God’s Word does not make it so. But if a book is God’s Word, it would certainly claim to be God’s Word. If a book is God’s Word, then what it said would be true. It may seem odd that we would cite the Bible to prove that the Bible is God’s Word. This is what philosopher’s call a “circular argument.” When we prove the authority of the Bible by citing the Bible, we have assumed from the beginning that the Bible is authoritative. Is this just a vicious circle of reasoning that won’t get us anywhere? It may seem that we need to prove the truth of the Bible by some other outside “neutral” standard. Of course, if we did that, we would have to ask what makes this outside standard authoritative? We would have only created another circle that needed defending.
There are problems with some kinds of circular arguments. But you might be surprised to know that you can’t help arguing in a circle. At some point, everyone has to argue in a circle. Why? Because everyone, as we have seen, has certain presuppositions. No one is neutral. When someone challenges your assumptions or belief patterns, you either have to use a circular argument, or you have to change your presuppositions, which will also lead to a circular argument.
[A] rationalist [for whom reason has final authority] can prove the primacy of reason only by using a rational argument. An empiricist [for whom experience has final authority] can prove the primacy of sense-experience only by some kind of appeal to sense-experience. A Muslim can prove the primacy of the Koran only by appealing to the Koran. But if all systems are circular in that way, then such circularity can hardly be urged against Christianity. The critic will inevitably be just as “guilty” of circularity as the Christian is.
Of course, not all circular arguments are reasonable or valid. For a person to claim that he should be worshiped because he is god, based on his own assertion that he is god, is not the type of circular argument that is being examined. “Circularity in a system is properly justified only at one point: in an argument for the ultimate criterion of the system.” But what happens when two circular arguments- each claiming ultimate authority for their worldview- don’t agree? Each worldview must be “put to the test,” working out the logical implications of the stated presuppositions. Which one best fits with reality? For example, the Bible contains thousands of prophecies about numerous events spanning thousands of years. The Bible sets the standard for determining how to evaluate prophecies: They must always come to pass; there can be no mistakes (Deut. 18:18-22). The Bible can be easily tested by its own standards.
(DeMar, Thinking Straight in a Crooked World, 100-101)