C.S. Lewis, the Moral Argument for God, and the Gospel
In the conclusion of his famous Critique of Practical Reason, Kant famously said, “two things fill the mind with ever new and increasing admiration and reverence… the starry heavens above me and the moral law within me.” Years later, C.S. Lewis picks up this Kantian insight and formulates an argument for God based on the reality of a Moral Law.Lewis thinks that the evidence from the Moral Law to God is better than the evidence from the reality of the universe since “you find out more about God from the Moral Law than from the universe in general just as you find out more about a man by listening to his conversation than by looking at a house he has built.” So, let’s look at the argument, found in the first five chapters of Mere Christianity, and summarized as follows:
1. There is a universal Moral Law.
2. If there is a universal Moral Law, there is a Moral Law-giver.
3. If there is a Moral Law-giver, it must be something beyond the universe.
4. Therefore, there is something beyond the universe.
In support of premise (1), Lewis argues that we all have within us the sense of right behavior and character. There is a sense of “oughtness” that presses upon us. He says, “human beings, all over the earth, have this curious idea that they ought to behave in a certain way, and cannot really get rid of it.” Lewis calls this law of right behavior the Moral Law. We live in a moral universe—in addition to the physical facts (“this chair is brown”, “Gold is atomic number 79”), there are moral facts (“lying is wrong”, “bravery is a virtue”). We find in the universe “a real law, which none of us made, but which we find pressing on us.” But if there is an objective Moral Law, and none of us made it, there must be something else that produced the Moral Law, a Moral Law-giver, hence premise (2).
Still, the “Moral Law-giver” could just be something within the universe—maybe moral facts just supervene on physical facts, such as facts about society or facts about (purely material) human nature. If so, then the Moral Law-giver (“society” or “natural selection”) would not be something beyond the physical universe, hence the theological conclusion (4) could be avoided. So, what is Lewis’ argument in support of premise (3)?
Here, I find Lewis uncharacteristically opaque. Here is how Lewis argues, as far as I can tell (in Chapter 4 of Mere Christianity, “What Lies Behind The Law”): The Moral Law-giver is either part of the universe or something beyond. If it is part of the universe, we would be able to observe moral facts, and the reality or power behind moral facts, via scientific inquiry. We cannot learn of the Moral Law or the law-giver from scientific inquiry, hence the Moral Law-giver is “beyond” or “behind” the universe.
I say, why not argue instead as follows: If materialism is true, there are only physical facts. But there are not just physical facts, there are moral facts as well. Religion best explains the reality of moral facts (and not materialism), hence there is something beyond the universe. And this something is more like ‘mind’ than an impersonal (say) Platonic abstract object (the Form “goodness” or “beauty”). Hence, premise (3).
Lewis is careful to point out that the above argument is “not yet within a hundred miles of the God of Christian theology.” All he has established is that there is something which is directing the universe, something that presses upon us a Moral Law.
But, if we live in a moral universe and there is something beyond the universe that is the source of morality—then, as Lewis says, we have reason to be uneasy. For the Moral Law is “hard as nails. It tells you to do the straight thing and it does not seem to care how painful, or dangerous, or difficult it is to do.” And to make matters worse, “we know that if there does exist an absolute goodness in must hate most of what we do. This is the terrible fix we are in.”
The reality of a power behind the moral law, a power that presses upon us and hates most of what we do is at once awe-inspiring and tragic. It is awe-inspiring to think that there is an absolute goodness, a power beyond the universe that presses itself within the universe. But, it is equally tragic for man—for we fall woefully short of the Moral Law everyday.
But this is the beginning of the gospel story. We must begin with man’s tragedy—that we are eight parts chicken, slob, devil—before we can understand the divine comedy of God becoming man, and the fairy story ending: that man can be forgiven for his sins and enjoy life, satisfaction, peace, and meaning with God. This is the gospel—tragedy, comedy, fairy story—and Lewis pointed out that one cannot understand the gospel until we understand this very terrifying fact—there is a Moral Law and we fall woefully short.
As Lewis states, “the Christian religion is, in the long run, a thing of unspeakable comfort. But it does not begin in comfort; it begins in…dismay….if you look for truth, you may find comfort in the end: if you look for comfort you will not get either comfort or truth—only soft soap and wishful thinking to begin with and, in the end, despair.”
 C.S. Lewis, Mere Christianity (New York: Harper Collins, 2001 edition), 29.
 I do not consider here the possibility that moral facts are just brute. If Platonic atheism is true, perhaps they are, but I think Platonic atheism false, and have briefly addressed why in my post “Atheism and the unscratchable itch.”