Excerpts from Miracles by C. S. Lewis (I encourage you to read the entire book.)
“All possible knowledge, then, depends on the validity of reasoning…. Unless human reasoning is valid no science can be true. It follows that no account of the universe can be true unless that account leaves it possible for our thinking to be a real insight…. Thus a strict materialism refutes itself for the reason given long ago by Professor Haldane: ‘If my mental processes are determined wholly by the [random, uncontrolled] motions of atoms in my brain, I have no reason to suppose that my beliefs are true…and hence I have no reason for supposing my brain to be composed of atoms.’ (Possible Worlds, p.209) But Naturalism, even if it is not purely materialistic, seems to me to involve the same difficulty, though in a somewhat less obvious form. It discredits our processes of reasoning or at least reduces their credit to such a humble level that it can no longer support Naturalism itself…. Acts of thinking are no doubt events; but they are a very special sort of events. They are ‘about’ something other than themselves and can be true or false. Events in general are not ‘about’ anything and cannot be true or false. [They just happen by cause and effect.] Hence acts of inference can, and must, be considered in two different lights. On the one hand they are subjective events, items in somebody’s psychological history. On the other hand, they are insights into, or knowings of, something other than themselves…. And we cannot possibly reject the second point of view as a subjective illusion without discrediting all of human knowledge. For we can know nothing, beyond our sensations at the moment unless the act of inference is the real insight that it claims to be….”
“Reason is our starting point. There can be no question either of attacking or defending it. If by treating it as a mere phenomenon you put yourself outside it, there is then no way, except by begging the question, of getting inside again…. For him [the Christian], the human mind in the act of knowing is illuminated by the Divine reason. It is set free, in the measure required, from the huge nexus of non-rational causation; free from this to be determined by the truth known….”
“The knowledge of a thing is not one of the things’s parts. In this sense something beyond Nature operates whenever we reason…. We have seen that rational thought is not part of the system of Nature. Within each man there must be an area (however small) of activity which is outside or independent of her. In relation to Nature, rational thought goes on ‘of its own accord’ or exists ‘on its own.’ It does not follow that rational though exists absolutely on its own. It might be independent of Nature by being dependent on something else…. It is only when you are asked to believe in Reason coming from non-reason that you must cry Halt, for, if you don’t, all thought is discredited. It is therefore obvious that sooner or later you must admit a Reason which exists absolutely on its own…. Yet if any thought is valid, such a [eternal self-existent] Reason must exist and must be the source of my own imperfect and intermittent rationality. Human minds, then, are not the only supernatural entities that exist. They do not come from nowhere. Each has come into Nature from Supernature: each has its tap-root in an eternal, self-existent Rational being, whom we call God. Each is an offshoot, or spearhead, or incursion of that Supernatural reality into Nature….
“Reasoning doesn’t ‘happen to’ us: we do it…. The traditional doctrine that I am a creature to whom God has given reason but who is distinct from God seems to me much more philosophical than the theory that what appears to be my thinking is only God’s thinking through me…. It seems much more likely that human thought is not God’s but God-kindled….”
“We are interested in man only because his rationality is the little tell-tale rift in Nature which shows that there is something beyond or behind her….”
“Two views have been held about moral judgments. Some people think that when we make them we are not using our Reason, but are employing some different power. Other people think that we make them by our Reason. I myself hold this second view. That is, I believe that the primary moral principles on which all others depend are rationally perceived. We ‘just see’ that there is no reason why my neighbor’s happiness should be sacrificed to my own, as we ‘just see’ that things which are equal to the same thing are equal to one another. If we cannot prove either axiom, that is not because they are irrational but because they are self-evident and all proofs depend on them. Their intrinsic reasonableness shines by its own light. It is because all morality is based on such self-evident principles that we say to a man, when we would recall him to right conduct, ‘Be reasonable.’… If we are to continue to make moral judgments (and whatever we say we shall in fact continue) then we must believe that the conscience of man is not a product of Nature. It can be valid only as an offshoot of some absolute moral wisdom, a moral wisdom which exists absolutely ‘on its own’ and is not a product of non-moral, non-rational Nature. As the argument of the last chapter led us to acknowledge a supernatural source for rational thought, so the argument of this leads us to acknowledge a supernatural source for our ideas of good and evil…. If, like me, you hold that moral judgment is a kind of Reasoning, then you will say, ‘We now know more about the Divine Reason.’”
“Reason is something more than cerebral biochemistry…. The presence of human rationality in the world is therefore a Miracle….”