C.S. Lewis and Effective Altruism

By Mike Morell

This post is based on a talk I gave in 2022 that’s still on YouTube. I thank Vesa Hautala (and ChatGPT of course) for help organizing it into a post. I’ve also added some new material here that wasn’t covered in the talk.

One of the interesting things about participating in the Christian effective altruism community is the variety of personal stories one hears, both in terms of individual faith journeys and how people were first introduced to the ideas of effective altruism.

I’m happy to share my own story in conversation, but in this post I want to highlight one significant aspect of it – my engagement with the writing of C.S. Lewis (1898–1963). Full disclosure: I’m not an expert on Lewis and do not know what he would think of effective altruism. I can only speculate on that, but I can speak more definitively of the effect he had on me.

A brief summary is that prior to about 2002, my faith was not a big part of my life, and about the only thing I knew about C.S. Lewis was that he had written the children’s fiction series The Chronicles of Narnia. By about 2006, however, I had devoured most of his nonfiction (and also enjoyed his Space Trilogy fiction). On the other side of that, not only had my faith life been transformed, but I was also putting into practice (albeit very imperfectly) a new group of ideas that seemed to me the best way for someone in my situation to apply Jesus’s teachings. Several years later, I would recognize many of those ideas being discussed, largely by secular folks, under the label “effective altruism” (“EA”), and only later did I go back and deliberately connect them to themes found in Lewis’s work.

My goal is to encourage readers not familiar with Lewis to discover his work. Furthermore, I hope that anyone trying to share ideas from EA with a Christian audience would be familiar with the various ways those ideas connect to Lewis, both because he is beloved by many but also because his words have a way of illustrating these ideas in a way that’s powerful and yet feels familiar and tempered by common sense. To start, I’m going to cover how Lewis talked about effectiveness, and how he talked about altruism. You don’t have to dig very deep to find these themes in Lewis’s work. The Lewis quotes are all from Mere Christianity, perhaps his most famous nonfiction work, unless otherwise cited.

Lewis on Effectiveness

Let’s jump right in. A key passage comes from the section on Prudence, which Lewis defines as

practical common sense, taking the trouble to think out what you’re doing and what is likely to come of it

There’s a hint of what philosophers call consequentialism in this. Lewis emphasizes that good intentions or feelings aren’t enough; we must thoughtfully consider the consequences of our actions for others and the world. Calling this “common sense” is in keeping with Lewis’s style. He often framed his insights not as innovative but as rediscovering truths that have always been there – whether rooted in scripture, earlier thinkers, or the broader world.

Later in that chapter, Lewis addresses a common misunderstanding:

Because Christ said we could only get into His world by being like children, many Christians have the idea that, provided you are ‘good’, it does not matter being a fool. But that is a misunderstanding … As St Paul points out, Christ never meant that we were to remain children in intelligence: on the contrary He told us to be not only ‘as harmless as doves’, but also ‘as wise as serpents’.

I think the reference here is to 1 Corinthians 14:20:

Brothers and sisters, stop thinking like children. In regard to evil be infants, but in your thinking be adults. (NIV)

Lewis reinforces this point later:

He wants a child's heart, but a grown-up's head. He wants us to be simple, single-minded, affectionate, and teachable, as good children are; but He also wants every bit of intelligence we have to be alert at its job, and in first-class fighting trim.

He applies this idea to charity as well:

The fact that you are giving money to a charity does not mean that you need not try to find out whether that charity is a fraud or not.

This point remains relevant today, of course, as there is still far too much fraud in the world. We can only speculate how Lewis may have expanded on this point were he writing today, but perhaps he would have recommended that his more analytically-inclined readers consider the rigorous charity evaluations that are freely available from EA-aligned sources like GiveWell and Happier Lives Institute, as well as the discussion available on EA Forum and the Christian materials on this site and our sister site, Christians for Impact (CFI).

Research shows some charities are literally 1000 times more effective than others. If we’re giving to charity – which most of us should, as I’ll discuss later – it’s essential to use our best intelligence to evaluate where our support will have the greatest impact.

Having said this, I’d offer a word of caution: effective altruism isn’t for everyone. Yes, there are objective moral principles, and some actions are better than others. But if we take our enthusiasm for data and analysis too far, we risk becoming judgmental about how others give. Each of us has different gifts.

Lewis clarifies:

It is, of course, quite true that God will not love you any the less, or have less use for you, if you happen to have been born with a very second-rate brain. He has room for people with very little sense, but He wants everyone to use what sense they have.

That last line might sound condescending. However, Lewis wasn’t putting down those who think more simply about what the Christian life entails. He explains in a later section of Mere Christianity:

It is as well to put this the other way round. Some of us who seem quite nice people may, in fact, have made so little use of a good heredity and good upbringing that we are really worse than those whom we regard as fiends. Can we be quite certain how we should have behaved if we had been saddled with the psychological outfit, and then with the bad upbringing, and then with the power, say, of Himmler?

That is why Christians are told not to judge. We see only the results which a man's choices make out of his raw material. But God does not judge him on the raw material at all, but on what he has done with it. Most of the man's psychological makeup is probably due to his body: when his body dies all that will fall off him, and the real central man, the thing that chose, that made the best or worst out of this material, will stand naked. All sorts of nice things which we thought our own, but which were really due to a good digestion, will fall off some of us: all sorts of nasty things which were due to complexes or bad health will fall off others. We shall then, for the first time, see everyone as he really was. There will be surprises.

For ‘man’ I think we can safely read ‘person’, as this was written in 1952. But this idea – reminiscent of the biblical principle “to whom much is given, much is required” – reminds us that we’re judged on how we use what we have available to us.

The key principle “love your neighbor as yourself” remains the supreme governor of our actions. If you “follow the spirit” or obey clear callings from God in making most day-to-day decisions for yourself and your family, then by all means do the same when helping your neighbor.

However, suppose you rarely if ever receive direct divine guidance. Perhaps when you ask God for answers all you feel is the silent gentle presence of a parent or teacher, looking over your shoulder but encouraging you to work out the answers to the problems set before you. And as a result, you rely first on reason and evidence to make good decisions for the benefit of yourself or your family, whether it’s where to live, how to plan finances, which laptop to buy, or what to advise your clients at work. You may have found that to be a sound approach; as Proverbs 21:5 puts it “the plans of the diligent lead to profit as surely as haste leads to poverty.” The corollary, however, is that you ought to apply that same thoughtful approach to helping others. Don’t settle for giving to the first charity that knocks on your door. Be deliberate and thoughtful in your career and charitable choices, using your reason and all the evidence at hand. Your neighbours matter to God, and they can benefit profoundly from your careful planning.

Lewis on Altruism

Lewis views altruism as central to Christian morality. Drawing from Ephesians 4:28 and Matthew 25:31–46 (for a take on the latter similar to my own, see here), he emphasizes the importance of giving.

In the passage where the New Testament says that every one must work, it gives as a reason "in order that he may have something to give to those in need." Charity – giving to the poor – is an essential part of Christian morality: in the frightening parable of the sheep and the goats it seems to be the point on which everything turns.

Lewis doesn’t reduce this to a works-versus-grace debate. Forgiveness and salvation, he argues, are gifts from Christ. However, if faith is genuine, good works will naturally flow from it. He challenges believers to measure their giving not by any particular percentage threshold but by sacrifice:

I do not believe one can settle how much we ought to give. I am afraid the only safe rule is to give more than we can spare. In other words, if our expenditure on comforts, luxuries, amusements, etc, is up to the standard common among those with the same income as our own, we are probably giving away too little.

If our charities do not at all pinch or hamper us, I should say they are too small. There ought to be things we should like to do and cannot do because our charitable expenditure excludes them.

This radical generosity should make Christians stand out. If one's charity doesn’t "pinch or hamper" them, Lewis argues, it's likely insufficient. There should be things we want to do but cannot because of our charitable commitments. While this principle isn’t as demanding as Christ’s command to the rich young man to give away everything, it’s a starting point – a test of whether Christian principles truly shape our finances.

Public vs. Private Obligations

A common tension arises between personal charity and governmental obligations. Should poverty and other social issues be addressed by individuals, or is it the government’s responsibility? It’s an old question, and certainly one that’s been front and center in 2025.

Lewis acknowledges that some argue charity would be unnecessary if society eliminated poverty altogether, and signals some sympathy with that idea. However, Lewis insists it doesn’t absolve individuals from giving in the meantime:

Some people nowadays say that charity ought to be unnecessary and that instead of giving to the poor we ought to be producing a society in which there were no poor to give to. They may be quite right in saying that we ought to produce that kind of society. But if anyone thinks that, as a consequence, you can stop giving in the meantime, then he has parted company with all Christian morality.

Lewis’ views resonate with some ideas of Peter Singer, whom many secular EAs cite as a significant impact on their thinking. While Singer is an atheist and holds views on topics like the sanctity of life that diverge sharply from Christian ethics, his arguments about personal responsibility in alleviating global poverty reach a similar conclusion to Lewis.

It is sometimes said that overseas aid should be a government responsibility ... this argument seems to assume that the more people there are who give to privately organized famine relief funds, the less likely it is that the government will take over full responsibility for such aid. This assumption is unsupported, and does not strike me as at all plausible. The opposite view – that if no one gives voluntarily, a government will assume that its citizens are uninterested in famine relief and would not wish to be forced into giving aid – seems more plausible…

I agree, too, that giving privately is not enough, and that we ought to be campaigning actively for entirely new standards for both public and private contributions to famine relief. Indeed, I would sympathize with someone who thought that campaigning was more important than giving oneself, although I doubt whether preaching what one does not practice would be very effective. (Famine, Affluence, and Morality)

Singer argues that individuals shouldn’t rely solely on government action. Instead, they should act decisively to address urgent needs. For example, Singer’s famous analogy of a drowning child illustrates this (and calls to my mind the parable of the Good Samaritan). Both Singer and Lewis challenge us to align our actions with the intellectual grasp of these moral principles.

Practical Difficulties

For many of us the great obstacle to charity lies not in our luxurious living or desire for more money, but in our fear — fear of insecurity… Sometimes our pride also hinders our charity; we are tempted to spend more than we ought on the showy forms of generosity (tipping, hospitality) and less than we ought on those who really need our help.

As Lewis points out, fear, exacerbated by societal messaging about saving for retirement, often holds us back. Pride, too, tempts us to focus on socially visible forms of generosity, like hospitality or tipping, rather than aiding those who truly need help.

This tension echoes Jesus’ teaching in the Sermon on the Mount, where He warns against giving for recognition. Helping local causes often results in gratitude and social validation, whereas giving to distant causes may feel impersonal, as there’s no direct interaction or acknowledgement.

Even Jesus’ own acts of healing weren’t always met with gratitude. Out of ten lepers healed, only one returned to thank Him. Thus, genuine charity doesn’t hinge on recognition but on doing what is right.

Some of the things the ordinary self wanted to do turn out to be what we call ‘wrong’; well, we must give them up. Other things, which the self did not want to do, turn out to be what we call “right”; well, we shall have to do them… we are hoping… that when all the demands have been met, the poor natural self will still have some chance, and some time, to get on with its own life and do what it likes... we are very like an honest man paying his taxes.

Lewis captures the difficulty of grappling with moral obligations. Many of us hope we can meet these demands with a “tax-like” payment and then live the rest of our lives unburdened. But the Christian way, according to Lewis, is both harder and easier.

Christ says “Give me All. I don’t want so much of your time and so much of your money and so much of your work: I want You.... Hand over the natural self, all the desires which you think innocent as well as the ones you think wicked – the whole outfit. I will give you a new self instead. In fact, I will give you Myself.” … Both harder and easier than what we are all trying to do. You have noticed, I expect, that Christ Himself sometimes describes the Christian way as very hard, sometimes as very easy. He says, “Take up your Cross” – in other words, it is like going to be beaten to death in a concentration camp. Next minute he says, "My yoke is easy and my burden light." He means both. And one can just see why both are true. Teachers will tell you that the laziest boy in the class is the one who works hardest in the end … give two boys, say, a proposition in geometry to do, the one who is prepared to take trouble will try to understand it. The lazy boy will try to learn it by heart because, for the moment, that needs less effort. But six months later, when they are preparing for an exam, that lazy boy is doing hours and hours of miserable drudgery over things the other boy understands, and positively enjoys, in a few minutes. Laziness means more work in the long run.

While Christ’s call to perfection is daunting, He doesn’t ask us to solve the world’s problems single-handedly. Instead, He offers grace and guidance. By surrendering ourselves to Him, we gain a new self and the assurance that, despite our shortcomings, all will ultimately end well.

Lewis contrasts this with the rule-following fervor that some readers (including the Pharisees whom Jesus called out in the Gospels) infer from the Old Testament (which Lewis elsewhere compared to a picture coming “gradually into focus”). The Christian moral framework can be stated simply: love God and love your neighbor. Yet this simplicity doesn’t diminish its depth or make it clear how to handle numerous complicated situations. Fortunately, we have Christ as an example and teacher. Lewis expands on the “harder vs easier” paradox here:

For you are no longer thinking simply about right and wrong; you are trying to catch the good infection from a Person. It is more like painting a portrait than like obeying a set of rules. And the odd thing is that while in one way it is much harder than keeping rules, in another way it is far easier. The real Son of God is at your side. He is beginning to turn you into the same kind of thing as Himself. He is beginning, so to speak, to "inject" His kind of life and thought, His Zoe, into you; beginning to turn the tin soldier into a live man. The part of you that does not like it is the part that is still tin.

Lewis applied many of these principles in his own life. One of his biographers highlighted the various ways he put his faith into action. For 30 years, Lewis cared for the mother of a friend who had died in the war. He and his family opened their home to children evacuated during air raids. On a personal level, Lewis made time for others – responding to every letter he received and connecting with people on an individual basis.

Financially, Lewis was extraordinarily generous. Early in his career, he gave away most of his royalties, which led to tax difficulties because he owed more than he could afford. Later, he worked with his lawyer to set up a charitable trust ("The Agape Fund") that funnelled two-thirds of his book earnings to widows and orphans – often anonymously. Some estimates say that 90% of his income went to charity, despite the fact that, according to George Sayer, Lewis inherited his father’s fear of bankruptcy.

There are no stories (to my knowledge) of expertise in charity evaluation on Lewis’s part. At the time, there were no outstanding reputable third-parties like GiveWell to help. Lewis lacked talent in math or investments, so he was unlikely to be able to do that kind of analysis himself. It seems likely, though, that if such information had been available, he would have brought his whole intellect to considering it.

Lewis on Animals

Effective altruism focuses on causes that are neglected relative to their importance and tractability. This has led to significant attention on animal welfare and long-term risks.

Lewis is claimed by The Humane Society as an advocate for animals in this long review that explores both his fiction and nonfiction. Lewis consistently advocated kindness towards animals, and was a firm opponent of vivisection, but didn’t speak to factory farming (in its infancy at the time), and was not a vegetarian. He pondered animal suffering deeply, but confessed doubts about which ones had souls, as reflected in The Problem of Pain.

How far up the scale … I will not even guess. It is certainly difficult to suppose that the apes, the elephant, and the higher domestic animals, have not, in some degree, a self or soul which connects experiences and gives rise to rudimentary individuality. But at least a great deal of what appears to be animal suffering need not be suffering in any real sense. (The Problem of Pain)

Lewis also speculated on possible animal immortality:

as we are raised in Christ, ...some animals are raised in us... we can only guess and wonder

more animals than you might expect are ready to adore man if they are given a reasonable opportunity: for man was made to be the priest and even, in one sense, the Christ, of the animals — the mediator through whom they apprehend so much of the Divine splendour (The Problem of Pain)

It’s difficult to know what he would make of today’s EA-aligned research about animal welfare issues. Compared to Lewis, modern analysts have a great deal more scientific data to work with, but many of them do not connect morality with God as Lewis powerfully does in Mere Christianity (for a fun video presentation of the relevant section, see here), and thus see many of the theological touchpoints he wrestled with as irrelevant. One thing I think we can be confident of is that he would not have been dismissive of the issue. For more resources on this, start here.

Lewis on Longtermism

EA frequently considers catastrophic risks, such as nuclear war, climate change, and pandemics, that could have very long-lasting impacts on human history, up to and including extinction. Some claim that finding ways to have even tiny probabilities of having a positive impact on the far future is more important than dealing with the very real and tractable problems of the present (or perhaps more precisely, that far future concerns are neglected relative to their importance, taking into account tractability). It’s a controversial topic even within EA.

Lewis offers an important caution: he reminds us that Christ could return at any time. The end of the universe is not necessarily when the last star burns out. It's whenever the curtain drops, whenever Christ decides to come back. This doesn't mean the problems longtermists are trying to tackle aren't important or that they might not deserve additional attention. Making them front and center, however, due to an assumption that the far future is extremely long, is a potential problem. Lewis is especially hard on those who pursue a future utopia by any means necessary, circumventing normal moral constraints:

I can imagine no man who will look with more horror on the End than a conscientious revolutionary who has, in a sense sincerely, been justifying cruelties and injustices inflicted on millions of his contemporaries by the benefits which he hopes to confer on future generations: generations who, as one terrible moment now reveals to him, were never going to exist. (The World’s Last Night)

Perhaps Lewis had various 19th-and-20th century political figures in mind; very few EA longtermists would endorse anything like that.

On the other hand, Lewis is not advocating a position strictly contrary to longtermism. He doesn’t disregard the welfare of people not yet born, and seems to be fine with looking ahead 100 years.

Frantic administration of panaceas to the world is certainly discouraged ... sober work for the future, within the limits of ordinary morality and prudence, is not … [such as] laying good plans to deliver humanity a hundred years hence from some great evil. (The World’s Last Night)

Most of the issues that pose risks to the far future also pose risks to the near future, and most of the risks that could lead to extinction could also just lead to very serious catastrophes. So perhaps philosophical differences should not stand in the way of cooperation with people with varying viewpoints working together on these problems. For more ideas, see CFI’s “problem profiles” on nuclear security, climate change, and pandemics.

Lewis on Artificial Intelligence

When I gave my first talk on Lewis, I didn’t have much to say about AI. For several years after I had become involved in EA, I was quite skeptical that it deserved as much attention as it was getting. I had thought at the time that the kinds of advances in AI capabilities that we all started to see about a year later with ChatGPT were decades away. Having been wrong about the timeline thus far, these days I’m feeling less entitled to an opinion on how things will play out from here. Experts diverge, with some predicting 2027 as a pivotal year, and others completely dismissive about the technology posing existential risks. If one gives some weight to each view, the composite prediction is still very concerning.

In a direct sense, Lewis had nothing to say about AI as we use it today. But in his writings he does explore closely-related themes. In an interview last year, John Lennox touched upon two of Lewis’s works that I read long ago, and hope to re-read again soon. That Hideous Strength has been noted by many commentators as especially timely; all I can recall at the moment is the part about the re-animated head. The Abolition of Man, about a powerful group of “conditioners” at a pivotal point in history, also resonates with observers as applicable to contemporary AI issues. Even those philosophically quite distant from Lewis have acknowledged The Abolition of Man as speaking into the dilemmas humanity faces as it closes in on building an artificial general intelligence and at some point an artificial superintelligence.

There’s a lot of work to be done in managing the risks and opportunities of AI properly, and it might be more time-sensitive than most of us realize. Christian voices appear to be underrepresented in this important field. Check out this presentation from the 2024 EACH Conference as a starting point.

Important Cautions

At its best, effective altruism reflects a commitment to impartial, rational, and impactful generosity that aligns well with putting Christianity sincerely into practice. Having access to a vibrant ecosystem of energetic people producing high-quality content about the world’s most important problems, as one finds at EA conferences or on the EA Forum, can be a great blessing to us and to the neighbors we are called to serve.

Nevertheless, there are areas where Lewis might caution us were he still here with us today. For example, EA sometimes aligns with utilitarianism – the idea that morality can be reduced to measurable values. Lewis warned against elevating any single principle, such as utility, above all others. In Mere Christianity, he wrote, “If you take any one thing and set it up as the thing to follow at all costs, you might turn into a devil.” Even the love of humanity, he emphasized, must include justice and other virtues to remain grounded. Moreover, he believed that inner transformation is essential; we must clean “the inside of the cup” as Jesus put it (Matt 23:26–28), before fully addressing the needs of others.

Another caution I suspect Lewis would want to offer to Christians engaging with effective altruism to realize that they are in the minority. According to surveys, around 80% of the EA community is non-religious. Furthermore, a sizable majority (according to informal polls, here and here) appears to subscribe to moral anti-realism (the view that there are no objective moral values). This isn’t always obvious given how much of the discussion in EA is about what people ought to do, but if you have a tendency to absorb the ideas of those you spend time with (whether in person or in print) it could be wise to be alert to it. Lewis’s famous essay on The Inner Ring is well worth reading.

Furthermore, practicing EA can expose a Christian to specific spiritual dangers. As just one example, keep Jesus’s parable of the Pharisee and the tax collector close to heart (Luke 18:9–14). Lewis alludes to it when writing about Pride, saying “whenever we find that our religious life is making us feel that we are good – above all, that we are better than someone else – I think we may be sure that we are being acted on, not by God, but by the devil”.

In my view, all of these cautions can be overcome by finding community with other Christians who feel similarly called to incorporate EA’s insights into their life, work, and charity. As iron sharpens iron, we can encourage one another to engage with EA in a way that is consistent with our commitment to Jesus. To start that journey or to get in touch with me directly, please reach out to the EACH/CFI team.