Adapted from his book, Christianity, The Faith That Makes Sense (Tyndale House, 1992)
What is a presuppositional argument?
Everyone has certain beginning points in their thinking. For instance, we may assume that our eyes see a real world. These beginning points are called presuppositions because we pre-suppose our beginning points are true. Without presupposing something we could not think or talk to each other. No one can avoid adopting some sort of presuppositions. But are our presuppositions consistent with our other beliefs? If not, we are a living contradiction. We say we believe one thing, but we really believe something else. This line of thought leads to the conclusion that a personal infinite creator God exists, and that he has created us as spiritual and personal beings.
An illustration may be the easiest way to understand this argument [This illustration is adapted from a similar one by Richard Taylor, cited in John Hick, Arguments for the Existence of God. (New York: Herder and Herder, 1971), pp.23,24].
Suppose two men are riding in a railway coach and glancing from the window at one of the stops, they see numerous white stones scattered about on a hillside near the train in a pattern resembling these letters:
THE CANADIAN RAILWAYS WELCOMES YOU TO CANADA.
One man observes that it took a lot of work to arrange the stones in that pattern, but the other disagrees. The second man sees no proof that any work was expended on the arrangement. After all, similar stones are scattered about on other parts of the hill, and they could roll down the slope periodically. He argues that the rocks may have simply rolled accidentally into this curious arrangement.
At this point, the first man may feel that the second man is being credulous and irrational, but he has to admit that he has no actual proof (from where they are sitting) that anyone arranged the rocks this way. He may feel his own explanation (that someone purposely arranged the rocks) is easier to believe than the accidental theory, but this judgment is based on probability and is somewhat subjective.
(So far, this is an argument from design. Now observe the further step we can take in our thinking based on the question of presuppositions.)
A few minutes later, the second man (who believes the rocks were arranged by accident) suggests that they should get out at the station and exchange their U. S. currency for Canadian money.
"What makes you think we should do that?" asks the first man.
The second man answers, "Can't you read?" while pointing to the rocks on the hill "It says we're entering Canada!"
"Okay, hold it right there!" the first man says. "You just claimed these rocks fell into this arrangement by pure chance, but now you're saying the arrangement of the rocks means we are entering Canada!"
The second man is acting in a way inconsistent with his own presuppositions. By suggesting they change their money, he has demonstrated that he, too, believes the arrangement of the stones is no accident. His conclusion that they are entering Canada, based on the arrangement of the stones, is inconsistent with his earlier claim that the stones had fallen into that pattern by accident. His actions and words demonstrate that he, too, believes someone placed the stones in this arrangement on purpose in order to communicate something.
Applying the Illustration
What is a presuppositional argument?
Atheists, agnostics and other naturalists are inconsistent with their own presuppositions all the time, just like this man in the train. By learning to identify those areas of inconsistency, we can help such people to see the strong likelihood that a personal creator-God exists.
Let's examine a few examples of this inconsistency.
Any time we use our reasoning ability to draw conclusions, and any time we look at patterns in the universe to discover truth (such as scientific laws) we are affirming by our actions that we already suppose there is a rational basis to the universe. Therefore, naturalists (e.g. materialists or atheists) who use reason are being just as inconsistent as the man on the train. Let's see how this works.
According to naturalists, everything in the universe is the result of chance and arose out of chaos. They see reality as a series of causes and effects, matter in collision with matter and energy, reacting according to natural law. If this is true, then everything that exists has been chemically determined. Chemicals and energy don't decide what to do when they collide. They do whatever the conditions and natural laws dictate. In other words, there is a cause and effect sequence in operation wherein each event has a given result. According to this naturalistic model, there can be no outside influence (like the human mind) that is not also a part of this cause and effect chain. What we think are free thoughts on our part are really just chemical reactions in the synapses of our neurons, according to this naturalistic world view.
If we, including our minds, are part of this cause and effect chain, all our thoughts and perceptions must be preconditioned by chemistry and physics. Why, then, would anyone with this world view think his own thought processes (themselves conditioned) could tell him anything about reality? Clearly, if we think our minds are not completely conditioned by natural law, we must presuppose the possibility that something non-material exists. We must suppose the supernatural exists.
The fact that we use our reason to interpret reality, and the fact that we trust these conclusions also shows that we believe that there is an orderly and rational basis to the universe. Such reasoning, and such confidence in reason is consistent with theism (belief in an infinite personal God, like the God of the Bible), not with naturalism (the belief that nothing exists but matter and energy). As theists, we argue that this reasonable and orderly basis behind the universe is none other than the reasoning and personal one who created all, and is himself the ground of all being.
Freedom and Morality
When we act as though we are free choosing beings, rather than determined ones, we imply that we believe there is a basis for freedom. Again, belief in personal freedom is only consistent with theism, never with naturalism. As theists, we argue that this basis is the eternally free and sovereignty choosing creator God who has made us in his image.
The same goes for morality. Morality is impossible without free choice. Suppose I use a chain saw to sever someone's head from his body. When the police come, they arrest me, not the chain saw, even though the chain saw actually did the cutting. Why shouldn't the chain saw have to serve a prison sentence along with me?
The answer is obvious. The chain saw is a machine, incapable of choice. It does whatever I make it do. Therefore, we ignore the saw from the standpoint of morality and go the first free-choosing being involved in the crime. Only when we are free to choose can we be held responsible morally.
People who accept that there is such a thing as morality must also presuppose a personal basis for morals. But naturalists have no such basis in their world view. Ask yourself, "Is it morally wrong to sexually abuse 3 year olds?" "Is this purely a personal moral preference, or is there a universal moral standard at stake?" If such a moral is universal, and lies outside of the individual's decision to make it a moral, then there must be a basis.
Chemicals bumping into one another cannot teach us that child abuse is wrong, or that human life matters. Quite the contrary! If we are purely matter, and are the result of material processes, then we are destined one day to perish as a race in the destruction of the present solar system. If this is so, what difference does it make how that matter is configured in the meantime? Whether our molecules take one form (a living person) or another (a decomposed body) could not be moral issue.
Neither could we explain why people are free under the naturalistic world view. If people are nothing but matter, they must do what they do because they were conditioned to do so. What other reason would there be? But if we were conditioned to do what we do, we are no more free in our choices than the chain saw. All morality disappears.
In one area after another, we will find that it is impossible to act in such a way that we are consistent with the world view of naturalism. Therefore this world-view fails the test of internal consistency, and should be rejected by honest thinkers. Instead, we should accept the fact that a personal moral and rational God has indeed created us and our world.
When people realize their presuppositions don't match their conclusions, they often become open to new information. We have the information they need! The universe is personal, moral, and free at it's core because its creator is personal, moral, and free. Notice that the presuppositional argument will not point to the pantheistic deities of the east. Only a personal and infinite God can account for what we see in the world.