The problem with C. S. Lewis’s moral argument – Part 2

This is the second part of my two-part account of what I made of C.S. Lewis’s moral argument for the existence of God when I encountered it in my early twenties, and why it didn’t convince me to become a believer.

Quick summary of material covered in Part 1 (statements below are summaries of positions, not direct quotes):

C.S. Lewis: We all share certain moral values which are universally agreed upon (don’t kill, don’t steal, don’t cheat, etc.). The universality of these moral values is beyond what can be explained by instinct or social teaching, and hence must indicate the existence of some kind of divine being who instilled these into humans.

Me: Hang on. Surely all these shared moral values are just as well explained by our ability to understand the feelings of others and accept them as objectively important in the same way as our own feelings are? Therefore meaning that these shared moral values don’t, in fact, necessarily indicate the existence of a divine being? All very interesting; need to think about this further.


So, I thought about it further. There were questions about my hypothesis that still needed asking:

1. Did it work? Rather an obvious point to consider. Did this basic principle – our understanding that the feelings of other people are also important – actually work to explain all of the moral codes that humans shared?

I did manage to think of one exception; the universal prohibition on incest. Of course, part of this is because in nearly all cases incest is abusive, and it hardly takes much thought (snark about Duggars deleted here because I don’t want to get too far sidetracked) to see how a principle like ‘Avoid hurting other people’ prohibits both sexual abuse and the hideous betrayal of family bonds. However, it’s also true that sexual relationships with close relatives are generally viewed as wrong even in those few cases where they quite genuinely are consensual. So there it was; one example of a universal moral code that didn’t seem to derive from consideration of the feelings of others.

However, this taboo didn’t seem to require me to hypothesise a morals-dispensing god to explain it; it seemed easily explicable in evolutionary terms. Having sex with a close relative would increase a person’s chances of having a child with health problems or a severe disability, and hence (because the small subsistence-level groups that humans had lived in for most of our history weren’t really in a position to support the disabled or those in poor health into adulthood) reduced their ability to pass on their genes successfully. People who didn’t want sex with their close relatives would therefore have an evolutionary advantage over those who did. Over time, we’d evolved a powerful and near-universal revulsion at the thought of sex with close relatives that had no more to do with morality than our opposable thumbs did; it was a genetic-level survival strategy.

That was the only exception I could think of; all the other universally shared moral codes I could think of were traceable back to a basic ‘do as you would be done by’ principle. Of those moral codes that seemed widespread enough to describe as universal, I couldn’t think of any that were so inexplicable as to require me to hypothesise a divine being to explain them.

2. Was I just not going back far enough? Our shared moral codes could be easily explained by our ability to appreciate that the feelings of others mattered – but what explained that ability? Was that something that could only be explained by the existence of a god who had endowed us with this skill?

No, I didn’t think so. Evolution had, over the millennia, shaped the human brain into a tool capable of amazing feats of intelligence and discernment. I didn’t see any reason why this complexity couldn’t also have produced the ability to understand the feelings of others. In fact – although I can’t remember whether or not I recognised this at the time – such an ability would in itself be an evolutionary advantage, since humans that lived together in co-operative groups where the members looked out for one another would have a better overall chance of survival than humans that tried to live and hunt on their own.

Two quick points here, in hopes of pre-empting objections:

Firstly, I do recognise that some people reading this may find this a sticking point; many theists believe that the complexities of the human brain and its abilities exceed anything that evolution can account for, and a small minority reject beliefs in evolution altogether. If so, then that’s outside the scope of this post to discuss, but it is worth noting that at that point you’re out of Moral Argument territory and back into Design Argument territory, which is something I previously commented on here.

Secondly, someone might well misunderstand this argument and think that I’m trying to claim that evolution can explain morality by itself and start explaining to me why it can’t. If so, you’re going to be attacking a strawman, since that’s not what I’m trying to say. What I believe is that the abilities from which we obtain this moral code – our ability to empathise with others and understand their feelings as important, our ability to think about what effect our actions may have on the feelings of others – can all be explained by evolutionary processes. We’ve then used those abilities to go far above and beyond the original evolutionary benefits they gave us, just as we’ve created great works of art with the manual dexterity that originally evolved to make us better at making the flint tools that would help keep our tribes alive; just as the Mona Lisa makes no difference to anyone’s survival, thus the moral code we now have involves far more than ‘what will best propagate our genes’. But I do believe that the original abilities that have enabled us to develop this moral code are explicable in terms of evolution and the ways in which it has shaped the brain. In other words, there is no need to look at them and see them as a mystery that only a god could have produced.


It seemed I had a solid, non-god-related explanation of why humans share a moral code. Which left me with one further important question to ask:

3. Which theory – mine or Lewis’s – was more likely to be right?

There was a simple way to assess this; I pictured the results we’d expect if Lewis’s theory were the correct one, and the results we’d expect if mine were.

If Lewis was right – if our shared moral code were a message from an interested deity wishing to let us know what behaviour was expected of us – then the first conclusion that seemed reasonable was that we’d expect to get a complete moral code. After all, it’s hard to see why a deity who’s interested enough to give us such a code in the first place would give us such a bare outline of it. Sure, we might not get every single detail spelled out; but we wouldn’t expect to have massive disputes over issues as fundamental as what did or didn’t constitute murder. If Lewis’s theory was the correct one, then we wouldn’t disagree over whether abortion or euthanasia or gay sex were OK. Our innate shared knowledge would cover all the significant issues, and that would be that.

(That, at least, was my reasoning at the time, which is what this post is meant to be about. However, an interesting logical alternative has occurred to me in writing this; we can, with just as much logic as Lewis used, hypothesise that our moral code was instilled in us by a being who didn’t include guidance on those issues because it genuinely doesn’t care about them. Which would mean that any moral beliefs not universally shared among human beings must be issues that God wasn’t bothere about either way. In other words, if Lewis’s Moral Argument theory was actually correct, then one logical conclusion would be that God isn’t actually bothered by such issues as gay marriage or abortion. I’m gonna bet today’s salary that you didn’t think of that one, Lewis.)

The other thing I’d expect if Lewis were correct would be that this shared moral code would include an innate understanding of the need to apply it equally to everyone everywhere. After all, why should this god care more about our behaviour towards people we knew or who we considered part of our in-group than it cared about our behaviour towards foreigners or other groups with which we couldn’t easily identify? Especially given that a key point of Lewis’s argument is that this code is universal among humans and that this is meant to indicate that this god cares about the behaviour of humans collectively and not just a subgroup thereof? So, if our moral code did indeed come from a god who cares deeply for all of humanity, we’d expect this code to include the same automatic care for all of humanity.

If, however, I was right about our shared moral code coming from our ability to understand and consider the feelings of others, then we’d expect to see quite a different picture. We’d expect there to be large disagreements between both individuals and societies on what constitutes moral behaviour – after all, just because we’re starting from the same basic principle of considering the feelings of others doesn’t mean we’re all going to have the same beliefs as to how this principle is best put into practice. We’d also expect that consideration for distant strangers would come with much more difficulty than consideration for people whom we perceive as being in our in-group, partly because we identify with the latter more easily and partly because, as I mentioned above, this ability probably evolved precisely because of the advantages of concentrating our energies on helping those in our in-group.

In other words… not only did my hypothesis explain perfectly well how and why humans share a near-universal moral code, it did so better than Lewis’s hypothesis. The facts of the world that I could observe all around me fitted better with my explanation than with his.

It was a shame; I’d really felt that Lewis was onto something new and interesting here. But his explanation didn’t hold up, so that was that.

And that’s why Lewis’s moral argument didn’t make me a believer.


  1. consciousness razor says

    However, it’s also true that sexual relationships with close relatives are generally viewed as wrong even in those few cases where they quite genuinely are consensual. So there it was; one example of a universal moral code that didn’t seem to derive from consideration of the feelings of others.

    But it isn’t universally viewed as wrong; like you said, it only generally is, even in cases when it is consensual. Someone defending Lewis’ moral argument (or any others, who simply don’t share our views against incest) could propose this shouldn’t be counted as universal anyway. That is, even if Lewis himself wouldn’t have agreed with it and would’ve thus weakened his own argument (as these defenders may reckon), we only have to worry about the strongest form of the argument, which should presumably entail tossing out anything that’s empirically inadequate, as this one apparently is. It isn’t an observed feature of moral reasoning/intuitions/feelings/whatever among all human beings everywhere and everywhen, so it’s just not on the table. You’ll just have to think of something else.

    On the other hand, when I try to do that, I start to run headlong into a bunch of problems. If we’re allowed to gerrymander the issue like this, it’s hard to say what exactly “moral” is supposed to mean and what work it’s supposed to be doing in the argument, since it doesn’t (in the argument) apply to all sorts of things which would ordinarily (and I think rightly) be considered moral (or political, which is just a word for a larger-scale version of the same thing). Even if they’re not universally shared, it’s not too hard to show that all of those things being left out of the analysis (or at least a sufficient number of important ones) are nevertheless distinctively moral, as opposed to pizza toppings or methods of calculating decimal digits of pi or anything else. It’d just be absurd to think practically every smart person who ever had anything to say about it, all over the world and throughout recorded history, was just mistaken about how they were using this term “morality,” since instead it means what Lewis must mean by it (if he’s going to mean anything), so we had better ditch all that and start over from scratch. That can’t be the right way to go.

    Anyway, it’s not actually critical to the concept of morality that every human person really does have some specific moral belief (e.g., that murder is wrong), because we certainly could be (and we certainly are) in a situation in which some people have moral views which are mistaken, confused, ignorant, not considered carefully enough, and so forth. Children, for example, don’t naturally have very well-developed ideas about morality and must learn them from others over an extended period of time. (Alas, some people never do, throughout their entire adult lives, it hardly needs to be said.) So this is apparently not a feature Lewis would need to ground real-world morality, but very inappropriately and gratuitously he jams it into the core of his argument anyway, only because it looks like a step in the right direction toward a cosmic/universal type of being (i.e., a god). It isn’t, but if you squint at it in just the right way and think about it for far too long and hope that you can conjure up the answer you were looking for from the beginning, I can imagine that it might seem to be.

    If everybody does share a view (i.e., that belief is a human universal), there simply won’t be any actual situations when we’d correctly describe a person as having learned from their mistakes about it, as making use of the wisdom/advice/experience/etc. of other people on that subjects, as being capable of making mistakes about it in the first place, as making a valuable contribution to moral thought, as maturing, becoming more nuanced or sophisticated, finally seeing the light, and so forth. All of that talk goes directly out the window, if a specific moral belief literally is universal – those things wouldn’t happen if that really were the case. But they clearly do happen, when you consider a whole lot of very important examples. (I’d challenge you to think of a single example to the contrary.) And once you see that, I think it should be clear how severely inadequate this is, as an all-encompassing notion of morality, that’s supposed to map onto interesting or important aspects of our lives that are widely understood to fall under that heading. You can’t even include rape and murder, FFS, because in fact there are people who believe those are okay, at least in some circumstances if not all. A very sheltered or naive or apologetic sort of person like Lewis might not think that’s true; but twisting their arms and getting them to agree about it isn’t the important thing here, just that the facts are on our side.

    Now, I think these days you’re likely to hear a very different argument (sometimes from theists, sometimes atheists) that evaluation, meaningfulness, etc., itself is a human universal. We all invariably do that, therefore GodDidIt, or perhaps EvoDidIt or whatever. It’s not a specific belief or code or what-have-you, like thinking incest is bad. It’s about the capacity for your life to have meaning (to you or others), for things to be important or interesting, for them to drive and motivate you in various ways, for your supposed qualia to have some kind of visceral qualitativeness about them which I guess is supposed to matter somehow. And so on and so on … many variations on the same basic theme. It’s all much more abstract and may just be unintelligible noise from people who have nothing better to say; but I just wanted to throw it out there and note that my objections above (pointing out a plurality of beliefs, far from unanimity) aren’t meant to apply to that kind of argument which can sometimes look superficially similar to Lewis’ argument.

  2. brucegee1962 says

    Regarding incest, I think it’s important to note that the taboos against it tend to be cultural, not biological. If two siblings are raised without any contact with the outside world, I have no doubt that they’ll happily screw one another. It is culture that passes down rules and laws and taboos against the behavior.

    That makes sense from a cultural evolution point of view. Back in the ancient world, there were probably plenty of cultures with no customs that discouraged incest, side by side with other cultures that did discourage it. Over time, as you point out, the groups with customs that allowed incest would start exhibiting fairly obvious genetic deformities, and would probably often die out. Then the other societies would strengthen their anti-incest taboos — “Whatever you do, don’t be like those sister-f***ers who lived over in the next valley. We all know what happened to them!” Allowing incest is simply a suboptimal evolutionary strategy for a group, and is thus dealt with ruthlessly by evolution’s laws.

  3. Owlmirror says

    Regarding incest, I think it’s important to note that the taboos against it tend to be cultural, not biological.


    If two siblings are raised without any contact with the outside world, I have no doubt that they’ll happily screw one another.

    Nope. Or at least, probably not.

    Scientific observations have shown something interesting: Children who are raised together in a sibling-like manner strongly tend to consider themselves siblings, and often reject mating with each other, even if they aren’t actually related. This has been observed in Israeli kibbutzim, where children were raised together in childcare crechés. It’s also been observed in certain child marriages — prepubescent children brought together by their families in order to unify those families.

    This is called the Westermarck effect, after the researcher who documented it.

  4. alkisvonidas says

    If Lewis’s theory was the correct one, then we wouldn’t disagree over whether abortion or euthanasia or gay sex were OK. Our innate shared knowledge would cover all the significant issues, and that would be that.

    A typical apologist would say that people don’t really disagree on the morality of abortion or gay sex; that “deep down”, they know these things are wrong, but are either insincere or in denial, or choose to pursue immoral behaviors out of selfishness.

    In fact, Lewis himself says as much: he points out that, while we all know what is moral and what isn’t, we more often than not fail to live by our own moral code, and excuse ourselves in various ways to others.

    In essence this is an unfalsifiable claim, since we can’t really know what other people believe “deep down”.

  5. Owlmirror says

    A typical apologist would say that people don’t really disagree on the morality of abortion or gay sex; that “deep down”, they know these things are wrong, but are either insincere or in denial, or choose to pursue immoral behaviors out of selfishness.

    I think one way to respond to this is to bring up Sabbath observance, circumcision, and/or kosher laws. Christians know that those laws are in the bible; they know that those things are what God commands — but Christians don’t feel obligated to obey.

    The usual excuses they bring up, like those laws being superseded by Jesus fulfilling the law, and/or the various proof texts in the NT and/or those laws only applying to the children of Israel can be turned around and applied to homosexuality and abortion (especially since the bible doesn’t specifically forbid abortion).

  6. Owlmirror says

    With respect to theists claiming universal morality, another point worth bringing up is the concept of disgust with respect to morality, a concept explored by some psychologists. The claims by theists about everyone “knowing” that homosexuality and/or abortion are wrong have an implicit claim that disgust is universal; that is, those actions should be rejected because they are inherently disgusting.

    So it’s worth emphasizing that disgust cannot be universal; that people can feel disgust from personal psychology (like picky eaters, of whatever religious belief, rejecting certain foods, or not wanting foods they like separately to be mixed together or even to touch on the same plate), or from general social or cultural factors (most people of European descent would feel disgust about eating locusts, even though the bible specifically permits that), or from specifically religious factors (Religious Jews feel disgust about eating pork and other non-kosher foods), and can change over time as well (non-religious Jews can have no problem with eating pork; some picky eaters can become less picky as they age).

    There’s more that could be expanded on here, but that’s the basic idea.

  7. Owlmirror says

    Another point:

    Disgust also seems to underlie a lot of prejudice and bigotry, both for people who look different, have different religions or cultural practices, or are injured/disfigured/disabled.

    So I think that’s worth pointing out as well.

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