C.S. Lewis and “Mere Christianity”: The Moral Law

C.S. Lewis

The very concept of some sort of “moral law” can be somewhat problematic, and can easily be twisted into a kind of fundamentalist legalism that sees all life and behavior in stark, black and white terms. You know that kind of person. He says, “God said it, I believe it, obey it or else! End of discussion! Tattoos? Nope! Leviticus 19:28!” He then proceeds to rip verses out of context to serve a “proof texts” that justify every one of his political or social positions. His mentality is, “The Bible is God’s LAW—obey it, or you’re gonna burn!”

Needless to say,  C.S. Lewis is not talking about that at all when he speaks of the Moral Law. That sort of wooden literalism of the Bible, with no consideration of historical context of any sort, does nobody any good. Rest assured, when Lewis talks about the Moral Law here, he’s not even talking about the Bible yet—he’s merely talking about that strange sense that all human beings have that there really is a real Right, and there really is a real Wrong in every situation. It is not just a matter of opinion. In this post we’re going to look at the next two chapters in Mere Christianity, and understand exactly what Lewis is talking about in regards to the Moral Law.

The Reality of the Law

In Book 1:3, Lewis focuses on one particular distinction—that of the difference between the Moral Law and the “regular natural laws,” like gravity, etc. The term “natural law,” can be a bit misleading, for in reality “natural laws” are really just descriptions of what nature actually does—it’s not like stones or trees have any choice in the matter. So in that sense, perhaps we should ditch the term “natural laws” and just use the term “natural descriptions”—that’s actually more fitting.

Simply put, “natural law” merely describes what nature does; but the Moral Law describes what human beings ought to do. And here’s the difference: human being, for some reason, have the choice whether or not to obey it. That’s actually quite an astute observation, if you ask me. It seems we have to accept the fact that this Moral Law is not the same as the other “natural laws”—it is unique to human beings, and human beings can obey or disobey it at will.

The last thing Lewis discusses in this chapter is the common modern notion that the purpose of the Moral Law really is nothing more than to benefit society. Lewis responds by saying that of course obeying the Moral Law benefits society, but that’s not the purpose of the Moral Law. If you tell someone they ought to be unselfish, he might say, “Why?” If you then say, “In order to benefit society,” he will reply, “Why should I care about that, except if it benefits me personally?” You will then have to say, “Well, you should be unselfish.” And you’re back to where you started.

The point is simple: the purpose of moral behavior cannot simply be to benefit society—although it certainly does. There must be something more. It would be like saying that the purpose of playing soccer was to score goals. Well, trying to score goals is the game itself—it’s not the purpose. The reason or reasons someone plays soccer can be many—develop discipline, encourage teamwork, or get in shape. You play the game in order to develop character, discipline, or whatever. That’s the “something more.”

If we reduce morality to something that merely helps society, we will be stripping morality of any real purpose, and it will be reduced to a sort of utilitarian act for the good of the collective or the state.

What Lies Behind the Law

In Book 1:4, Lewis then asks the question, “If there really is a Moral Law, then where did it come from?” He first says there are basically two views: (1) the materialist view, which we can all philosophical naturalism. It’s the view that says nature and natural processes are all that is, and somehow, someway, nature randomly produced creatures like us who developed big brains who came up with this notion of morality.

SIDE NOTE: This view of philosophical naturalism, by the way, is often confused with the actual scientific theory of evolution. The two are not the same. Evolution is nothing more than a description of natural processes; philosophical naturalism declares there is no God, and that natural processes are all that exist. If you fail to see that distinguish, you’re going to get a lot of things wrong in the whole “creation vs. evolution” debate.

The other view is what Lewis calls (2) the religious view, the view that there is something or someone behind the Moral Law who is responsible for it. Lewis notes that the religious view is not necessarily “against science,” even though many assume it is. The reason for this is because many people misunderstand what science actually is. Lewis points out (as I have above) that the job of science is to describe how things in nature behave, but it’s job is not to speculate whether or not there is something behind the natural world. Even if science was able to describe everything in the natural world, it would still be unable to answer questions like “Why is there a universe?” or “Is there any meaning in the universe?”

With that, Lewis then makes another good point. If (and only if) there was something beyond or outside of the natural universe, it wouldn’t be able to show itself as one of the facts inside the universe—“no more than the architect of a house could actually be a wall or staircase or fireplace in that house.” So if that is the case, how could that Someone or Something make itself known? Lewis’ answer should be obvious: we human beings cannot “get into the minds,” so to speak, of anything else in nature other than ourselves. And when we look inside ourselves, we find that we have this “sense” of right and wrong—we have this non-material urging within our own minds regarding rightness and wrongness. It seems, Lewis says, that it is this very Moral Law that is pointing to the existence of a reality beyond the natural universe.

Regardless how some have tried, science cannot explain the reality of morality, of why we should do some things and not others; of the ought in our lives. It is this sense of morality, Lewis says, that gives us a clue to something beyond the natural universe that gives actual meaning and purpose to our lives that a mere description of the laws of nature cannot.


So, do you agree with what Lewis says about the Moral Law? I think he makes a compelling argument that our very moral sensibility cannot be just another product of natural processes. And I think his point about if there is a power outside of the natural universe that he couldn’t show himself as a part of the universe. That is why we can never “prove” the existence of God in any scientific sense. If we could, then whatever we proved wouldn’t be God. No, if there is a God, he’d have to show himself in some other way—and that is what the Moral Law does: it is something we find inside ourselves, creatures and products of biological processes. Such moral sensibility is unique to human beings, so how did it get there and where did it come from?

Lewis is right: it points to the possibility of a reality beyond the natural world.



  1. I once heard that people who share that “God said it, I believe it, obey it or else! End of discussion!” mentality are actually putting more faith in themselves (viz. in their ability to accurately and completely interpret scripture with once simple read) than they are in God. How true!

    1. Yes, that is one of the unintended consequences of the Reformation. When you completely throw out Church Tradition and any consideration what the Church has taught about any given passage in the Bible, all you’re left with is the Bible and your own autonomous self. Ever since the dawn of the Reformation, history is littered with men claiming they’re reading the “plain meaning” of Scripture, and claiming the illumination of the Holy Spirit, and then going out completely destroying someone who makes the exact same claim, but comes up with a different interpretation.

      Proper Biblical interpretation takes patience, humility, and a lot of critical thinking–and then more study after that! Sadly, this is what we see coming from a lot of ultra-Fundamentalist camps. It amounts to Bible idolatry in my opinion.

  2. My problem with the Moral Law having a common source for everyone is that it varies greatly from person to person. I believe each person develops a sense of right and wrong based on a number of criteria such as upbringing, personal experience, teachings of others, etc. Thus each person develops his or her own personal morality. However, a large number of people seem to understand that if you don’t want other people doing unpleasant things to you, you shouldn’t be doing unpleasant things to them. Thus, the Golden Rule just naturally stems from that understanding. Given that a large number of people have this moral code in common, it becomes a de facto “moral law” that just seems natural to us. It may appear that some supernatural source planted it, but in reality it is just a large number of people agreeing that it is a good idea for a peaceful and orderly society. (NOTE: Joel, I have noticed quite a few errors in your blog posts due to insufficient proofreading. Just wanted you to know in case you wanted to start reviewing your writing more thoroughly before posting.)

    1. Lewis actually addresses this very thing, Randy. He readily agrees that there are differences in people’s moral sensibilities, and the moralities of various societies and cultures, but he argues they have never amounted to complete differences: there has never been a society where running away in battle is respected, etc. That’s the problem, though with calling this “thing” the “Moral LAW.” It gives the impression that it can only be sort of an “imposed” thing. Perhaps “Moral Sensibility”? I don’t know. But the point to really consider is that this “Moral Whatever” is unique to human beings. We, unlike other animals, try to convince the other person that they are in the wrong, or we make excuses for ourselves when we are found to be in the wrong. Other animals just attack each other or eat the other’s babies, or fling poo. (Sort of a joke there). Whatever you call it, given the fact it differs from person to person a little bit, the fact is that it is REALLY THERE, and it is unique to humans. That’s the point Lewis is making.

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