C.S. Lewis’ Case for God: The Reality Behind the Moral Law


It’s almost a cliche to say that C.S. Lewis’ classic work, Mere Christianity, is what introduced someone into apologetics or pulled them back to the faith…

And I’m among those who would invoke that cliche…

I’ve read Mere Christianity dozens of times since I first came across it when I was 16 years old and it goes without saying that C.S. Lewis has had a profound impact on my intellectual and Spiritual life…

In fact, a recent survey rated Mere Christianity as the best Christian book in history beating out works like St. Augustine’s Confessions and John Calvin’s Institutes. (I’d link my source but I can’t find it, sorry!)

From the perspective a philosopher and theologian, I’d certainly say that Mere Christianity is certainly high on the list from a literary perspective…

But the thing is that I really don’t think that it presents the most definitive or intellectually rigorous case for the Christian faith or even just the existence of God, although it is certainly worthy of consideration on that account as well…

Perhaps that’s why some say that Mere Christianity is perfect for the half-converted…

I really have found that the arguments Lewis forwards in Mere Christianity almost always tips the scales in favor of the faith for those wavering between belief and unbelief…

Throughout my years of experience in youth ministry, Lewis’ arguments for God’s existence have proven to be among the most effective in helping a teen wrestling with doubt find the strength to fight the temptation to give up in the face atheist arguments with nothing more than meme-level sophistication…

Those of you who are familiar with Lewis’ work already know where I’m going with this but for those who don’t, Lewis offers two arguments for God’s existence in Mere Christianity

Widely known as the “Moral Argument” or “the argument from moral truth” Lewis and other proponents of the moral argument look to our moral experience as evidence for the reality of some authoritative source of moral truth.

Because Christian philosophers have expanded and developed various ways of expressing the Moral Argument, I will freely draw from various versions and not exclusively rely on Lewis’ argument in Mere Christianity— which I recommend that you read anyway.

What Lies Behind the Law

When C.S. Lewis makes the case for God through the reality of moral standards, he doesn’t do so by making a formal argument but spreads out his case over the course of five chapters. For the sake of brevity, I’ll use a common way of phrasing this argument in the form of what’s called a conditional syllogism:

Observation: Moral truths exist and morality requires a rational nature.

  1. If God does not exist then objective moral facts, values, and duties do not exist.
  2. Objective moral facts, values, and duties do exist
  3. Therefore, God exists.

Before I go on to support the different parts of this argument I want to make something perfectly clear:

This argument DOES NOT SAYS that atheists cannot live morally upstanding lives.

I’m going to copy-past that because I cannot tell you how many times I’ve said that and then have the very first objection to the argument be “well, atheists can be good people too!” *facepalm*

So, I repeat:

This argument DOES NOT SAYS that atheists cannot live morally upstanding lives.

Okay, anyway, here we go with the argument:

Although not every atheist is a reductive naturalist, it seems that your garden variety atheist holds that little or nothing exists outside of the material and natural world that we observe. This leaves us with at least two major obstacles for this kind of atheist.

First, since only material things exist then whatever claims we make about the world must have some basis in matter. However, one cannot place “justice” in a centrifuge or measure its atomic mass. At best, we may see what we call “justice” in a sociologist’s observations regarding change in a culture’s mores but that only imports a value judgment onto what is intrinsically value-neutral.

Second, the reductive materialist must overcome the necessity of freedom for an act to be considered morally good or evil. When my internet cuts while I’m Battle Front 2, dominating as Darth Vader, I don’t stomp over to my router and chew it out. It hasn’t suddenly joined the Rebel Alliance due to some free choice. What would a scolding accomplish? No, I unplug it and hold the power button for 30 seconds before turning it back on. We chastise people and call them wicked or praise them for their virtue because we at least believe that they are more than just machines and can make decisions. However, reductive materialism does not allow for anything about human nature to act against our hard-wiring to behave or think in a certain way. As Richard Dawkins says, we can only dance to the tune of our own DNA. Without free-choice, morality is impossible and since reductive materialism does not allow for free choice then there can be no objective moral reality if reductive materialism is true.

Taking a look at a more metaphysically robust atheism, one which allows for more than the “atoms and the void” of Democritus, it seems that any attempt to establish a ground for objective moral truths either resolves into some form of subjectivism or ultimately relies on a theistic worldview.

One of the more recent attempts comes from neuroscientist Sam Harris trying his hand at philosophy. Although Harris is a consequentialist, what’s remarkable is that his argument for objective moral truths bears a striking similarity to the classical natural law theory of ethics. So, I actually find myself agreeing with him more often than not on some of the general principles for determining moral truths.

In A Moral Landscape, which is an outgrowth of his PhD thesis, Harris argues that the most relevant moral framework is one that is concerned with the well-being of conscious individuals. He argues that we find that there are some people who live clearly better lives than the lives lived by others. This well-being relates in a law-like and non-arbitrary way to brain-states and conditions in which some people live. Thanks to modern technology, we are now in the position to measure and work towards maximizing the well-being of conscious individuals by working to bring about the conditions that elicit the brain-states associated with well-being.

Harris’ theory allows both individuals and societies to point to some real, objective feature of the world which serves as a measure for the ethical quality of our actions. Furthermore, his project bypasses any notion of Platonic moral objects as the ground of values but establishes a moral system on the natural world.

Before any criticism, Harris rightly deserves praise in that he does not succumb to the trendy moral subjectivism found on the lips of a community college Ethics 101 student who wants to prove his enlightenment.

One of the most high-profile rebuttals to Harris’ attempt at a natural foundation for moral truths comes from Christian philosopher Dr. William Lane Craig who launches two primary attacks on Harris’ position. Craig’s first argues that if naturalism is true then morality is, de facto, a product of evolution in the same way hands or teeth are biological adaptations.

First, Craig argues that “natural science only tells us what is, not what ought to be the case.” Neuroscience, sociology, and other natural forms of knowledge, according to Craig, can only provide us with information on what happens to be the case but it cannot tell how we should act and nor can the discoveries of natural science produce a moral obligation to pursue human flourishing.

On a naturalistic point of view, humans are just another instance of animals and animals do not have moral obligations to one another. For example, a lion has no obligation to the zebra and, in fact, when a lion hunts and eats a zebra, the lion kills the zebra but does not commit murder. His point is that interactions between animals have no moral dimensions and have no prohibition or obligation to take certain actions.

Following this same line of reasoning, an atheistic world view only allows for a moral system that is the product of a particular line of evolutionary development, just like our hands or eyes. If we had followed a different evolutionary path then we would find ourselves with a radically different moral system. For example, should bees have descendants that attain human-level rationality then it is not unreasonable to think that it would be good for members of that species to kill their brothers and sisters because fratricide contributed to bee well-being in their evolutionary history.

In other words, if atheism is true then moral truths are only as objective as our species. But this reduces to a form of species-specific relativism.

Of course, humans are different from other animals due to our capacity for reason and social nature. Humans are more than qualified to understand the consequences of our actions, especially as they impact other conscious, rational beings who can suffer or flourish in a qualitatively higher way than any other creature. We must act with empathy and do our best in limiting gratuitous suffering and maximizing the benefit we provide for our fellow human beings.

But how and why does the addition of rationality make actions that maximize human well-being morally good?

In other words: how does Harris’ moral landscape bridge the gulf between statements of fact and statements of value?

Harris’ answer to this question is simple: because “moral goodness” simply means maximizing the well-being of sentient creatures, by definition.

Hence, for Harris the question “Why is maximizing the well-being of sentient creatures good?” means nothing more than “Why is the maximizing the well-being of sentient creatures maximizing the well-being of sentient creatures?” The question is nothing more than a tautology.

On this basis, how Harris bridges the gap between facts and values should be clear, and Harris makes three arguments as to why his theory solves this problem:

  1. Facts about what maximizes the well-being of conscious creatures naturally translates into facts about brains.

    In response, Dr. Craig merely highlights that Harris’ first point here may not actually be relevant to the question. The question still remains, says Dr. Craig, “if atheism is true then why do we have any obligations to maximize the well-being of conscious creatures? Or why is doing so even good in the first place?”

    The way I see it, Craig’s reply to Harris may beg the question against Harris to some extent, at least in consideration of Harris’ next point. Harris’ definition of moral goodness just is whatever actions maximize the well-being of conscious creatures.

    The bigger problem for Harris’ position is that his reliance on brain-states to guide our moral values is, well, unreliable.

    Near the end of Harris’ book, he admits that his Moral Landscape is more like a mountain range that contains peaks and valleys of well-being. People who are absolutely deplorable, such a serial child-rapist, could and do feel rather high degrees of mental well-being with all of the proper brain-states associated with well-being. This destroys Harris’ brain-state foundation for moral goodness because brain-states associated with well-being are at least sometimes indifferent to the person’s moral character or the character of their actions. Since there are times when these brain-states do not correspond to the character of certain actions or persons then “goodness” and “the well-being of conscious creatures” are not identical. Hence, Harris is wrong to say that “goodness” simply means “the well-being of conscious creatures”. From what I’ve read or heard from Harris, he has not given reasons why his theory still works in light of this major difficulty.

    One response to this argument against Harris’ position would be to say that the child rapist obtains his state of well-being only by depriving a child of well-being. Hence, the child rapist acts unjustly because of the harm he does to the child. But why should that matter on Harris’ view? One would have to smuggle in some outside standard to make the case that the brain-states of one kind of person should be valued more than that of another.
  2. Our objective knowledge is already value-laden and therefore the transition from fact to value is kind of like the hand off from a quarterback to a to a running back: it’s the same ball but now we’re just doing something different with it. Since we must value logical consistency, the same values we find in our fact-seeking must also be valued in our moral system.

    In response to this, Dr. Craig claims that Harris is merely equivocating on the term “value.” We may value logical consistency as a necessary part of our pursuit of objective facts but there is no indication that such a value translates into a moral value.

    On this point, I actually agree with Harris rather than Craig but only if we expand and then Harris’ position a bit. In some places in his book, Harris offers examples of non-moral uses of the term “good” such as when he says that a certain chess move is “good” or that a “good-knife” is sharp. In a similar manner, when we talk about the “goodness” of a moral action then we simply mean that we bring about the well-being of a human person.

    Is the term “good” used differently in reference to a “good” chess move and a “good” moral action? No, it isn’t because “good” should be understood sort of like a genus that can be further divided into different species. If I were to modify and strengthen Harris’ position then I would add that “goodness” must always be understood in relationship to an end. The goal of chess is victory over your opponent and a chess move is judged good or bad in light of that goal. Likewise, a moral action is good or evil only in light of the goal of being a human. For Harris, the goal of being human seems to be obtaining the brain-states associated with well-being. Even though Harris’ identification of a state of well-being with the end is mistaken, as illustrated above, his general but unspoken assertion that “goodness” is analogical is correct and overcomes Craig’s criticism.

    Craig’s criticisms, however, are only overcome if Harris’ case is bolstered by a Thomistic metaphysical schema and introducing the distinction between the role of a philosopher and the role of a logician.

    First, if morality is to be objective then the “end” or “goal” of human nature must likewise be objective. Harris’ comparison of a good knife as sharp to the goodness of certain human actions is pedagogically appropriate but does not adequately convey they difference between the end of an artifact, like a knife, and the end of a natural thing, like a man.

    The end of a knife is given by its craftsman and if it’s a chef’s knife then it’s a good knife if it is sharp enough for a chef to adequately slice food in preparation for a meal and a bad knife it is is too dull to cut through a tomato. We know the qualities that a chef’s knife ought to have precisely because we know what a chef’s knife is and for what it’s intended.

    Can the same be the said of man? Although Harris explicitly rejects innate end-directedness in natural things (also known as teleology), his argument by analogy requires that teleology is a real feature of human nature. Humans differ from knives in many ways, obviously, although I have been told that I do look rather sharp. On the subject of teleology, humans differ from knives in that whereas we determine the telos, end, or goal for knives, we discover such things in man as something given.

    Man as a whole and our various faculties operate towards the same end always and for the most part. As rational animals, it is good for us to eat, move, and reproduce because of our animalistic powers but our intellectual powers receive fulfillment in the discovery of what is good, true, and beautiful. At the risk of over-simplifying a more nuanced presentation of natural law ethics, we can say with confidence that the stomach is for digesting food, lungs are for breathing, and our reproductive organs are for reproducing and all of the parts of the body are for the flourishing of the whole organism.

    All of these ends are easily known simply because we know the facts of what a man is and, as Harris says, these facts are laden with value. Craig rejects this position, but he does so because he fails to appreciate the distinction between a logical essence, which is about definition, and the essence a philosophical essence, which is about the principles of being at work in a real thing. Hence when Craig thinks “rational animal”, he’s only thinking about an essence as a logician would and an a logical essence is inert. A philosopher, however, looks to the way a thing’s operations as they exist in reality rather than just in the mind. Since everything that acts will act for some end, and that end is always a good–whether real or apparent– then it is no stretch to say that given what a thing is then it ought to act a certain way towards the good. At this point, we have “ought” as something of a metaphysical term that conveys that everything acts towards an end, that end is good for that thing, and we know which goods ought to be done because of that thing’s kind.

    Alright, we’re not quite at the duty sense of “ought” yet but we aren’t too far away. What makes human actions different from brute animals or inanimate things is that we possess the power of free-choice by virtue of our intellectual natures. It is this element of freedom to choose to fulfill or reject our proper ends that gives “ought” a moral quality when we speak of human actions. No matter what action we take, we are always seeking some good but we are often mistaken or too weak-willed and choose apparent goods over the real good that we ought to pursue. In this way, we are not using the term “ought” in a way that is univocal or equivocal but analogical, which is not allowed in strict formal logic but is a perfectly fine in demonstrative logic.

    This distinction in crucial because formal logic requires that every term is used in exactly the same way because we are trying to clarify the meaning terms. Demonstrative logic, on the other hand, takes the same reasoning principles we find in formal logic but applies it to how things operate in the real world.

    Hence, there is no fallacious reasoning involved in the movement from facts about the way things are to the way they ought to be.

    Again, I’m just painting with a very broad brush, so lets not worry about the details at this time. Now that we know that the human “ought” has a moral character, we can quickly cover how we have “duties.” A duty is something done for another and since humans are social in nature, there are certain things that each individual ought to do for the sake of others humans because it is good both for the individual actor and for other members of his community.

    More remotely and more fundamentally, we have a duty to God to act towards real goods. As we will see later on with St. Thomas 5th way of demonstrating the existence of God, natural things which operate for an end only possess their respective natures because at every moment God commands not only their natures but also their very existence into being. Hence the duties we have are more than just a metaphysical necessity but also contain an element of obligation to the God who gives us our very being.

    Ultimately, Harris’ attempted escape from the is-ought fallacy does work but it needs some help from St. Thomas which, unfortunately for Harris, ends up leading to God in the long run.
  3. The brain states associated with beliefs about facts are closely related and similar to beliefs about values.
    Here’s how Craig responds:

    ” So what? Does Harris think this implies that they are the same belief? This confuses the origin of a belief with the content of the belief. Just because two different beliefs arise from similar brain processes does not imply they have the same meaning or information content. Whatever their origin, beliefs about what is the case, and beliefs about what ought (or ought not) to be the case are not the same belief. One belief could be true and the other false. Harris’ view thus lacks any source for objective moral duty.
    Here I think that Craig’s reply is most fitting in that he points out that Harris conflates the content of a belief with the origin of a belief. It may be true that our beliefs about facts arise from similar brain-states as our beliefs about value but how do brain activities associated with certain beliefs give any credence to their veracity?”

    His argument would have to be something like:

    I. Beliefs about facts are that which arise from brain-states X^1a
    II. Beliefs about values are that which arise from X^1b


    Nothing because nothing logically follows.

    It would seem that Harris has produced one of those rare four-term fallacies that isn’t equivocation. So, bravo on that.

Objective Moral Facts

Unfortunately, this post has gone on far too long. So, I will just give you a few clues to the reality of objective moral facts.

  1. Some things are universally and obviously recognized as good or evil.

    No society would advocate for a sport which involves tossing babies up in the air and catching them on pitchforks. On the contrary, anyone who partook of such an event would likely meet a swift end at the hands of their society.

    Virtues such as courage are universally praised. With the exception of “Brave Sir Robin”, there has never been a song written to laud the coward’s shrinking in the face of the mildest difficulty.
  2. Disagreements point to more fundamental agreements.

    Some cultures engage in cannibalism, others do not, and some cultures engage in cannibalism for different reasons. Maui warriors would consume their enemies because, graphically, they would then literally turn their enemies into feces. Gross, yes, but it’s one heck of a dig against a person’s honor to be turned into poo. Other cultures consume the remains of their deceased elders because they wish to honor their ancestors by allowing the deceased to live on, in a sense, through incorporation into the bodies of living relatives. Societies which do not engage in cannibalism tend to believe that to do so would disrespect the deceased.

    Also, it’s gross.

    The common thread is the idea of honor or respect as something which we ought to offer to others but the expression of that value differs in each. Perhaps the reason why this is the case is because certain core moral truths, such as offering respect or being courageous are more obviously true while other moral truths are more difficult to perceive.
  3. We “bump” into the moral law.

    All of us have had an experience where we’ve done something we know to be wrong and quickly ran into consequences. As a kid you probably lied to your parents about eating candy while you have chocolate smeared across your face. Time outs all around.

    Other times, we experience the consequences of our actions by what happens to our character rather than some imposed punishment from an outside authority. A person who deliberately chooses in many small ways to take the easy way out, exert minimal effort, or cut corners will, in a law-like manner, develop a rather slothful character.

    Often these experiences are at least as real to us as bumping into a wall or stubbing your toe, but worse because they impact your internal character.

    Burden of Proof

Even if it can be difficult to distinguish between good and evil actions, our experience of moral truths is so fundamental to our every day experience that denying the moral law is akin to denying physical reality. Given that this is the case, just as anyone who would deny the reality of the physical world would have to give some pretty damn good reasons to overturn belief in the physical world, so too would someone who wishes to deny the moral law shoulder a HUGE burden of proof.

Wrap this up, seriously.

Okay, okay.

Could I offer more arguments? Yes, of course, but this has gone on too long.

In any case, I think that what I’ve written above provides at least some good reasons to think that the premises of the moral argument are true.

Just by way of a reminder, here’s the way I formulated the argument:

  1. If God does not exist then objective moral facts, values, and duties do not exist.
  2. Objective moral facts, values, and duties do exist
  3. Therefore, God exists.

I spent most of my time on the first premise and offered some arguments to support the idea that any attempt to ground moral facts on anything but God lead to either some form of relativism/subjectivism or ironically leads to God.

The second premise received less attention, though some additional support for the second premise can be found in my discussion of Harris’ Moral Landscape. Regardless, the facts of moral consensus, disagreement, and experience point to a moral law that imposes itself upon us and is discoverable by us in a way similar to the discovery of physical laws.

Since the logic of the moral argument is unassailable, via denying the consequent, and the premises seem to be more true than false then I do think that the moral argument works as an argument for God.

To an extent.

Unless one takes an approach to the moral argument through St. Thomas 5th way, the moral argument only leads to some moral law giver and that’s about it. There are some further arguments that could get us to a necessary being, possibly, based on the necessity of the moral law, but it’s unclear whether that necessary being would be necessary through itself or through another. It’s also reasonable to conclude that the moral law giver is rational, since morality is a rational enterprise, but there is no indication that such a being would be all-knowing.

Without a Thomistic metaphysical background, I don’t really see how the moral argument points us to the God of Classical Theism.

So, the moral argument falls into what I consider to be “hints” or “clues” to the existence of God.

Hence, next week, I’ll cover how St. Thomas’ five ways work as a way to prepare you for a deeper analysis of the five best arguments for God in the history of philosophy. Ones which I believe have never encountered refutation.

Should be fun!

Jonathan L. Stute, M.A., MaPhil

P.S. As you can well imagine, there is a lot more to say about this argument. So, since you’re interested, you should check out my friend’s course on the Moral Argument for the Existence of God (click link). Dr. Sullivan has been a friend of mine and a philosophical mentor for me since 2015. You’ll see a lot more in his course than what I’ve provided in the blog. Check it out:

Moral Argument for the Existence of God (click link)