The Moral Equivalent of the Parallel Postulate

(Update: further discussion here and here.)

Sam Harris gave a TED talk, in which he claims that science can tell us what to value, or how to be moral. Unfortunately I completely disagree with his major point. (Via Jerry Coyne and 3 Quarks Daily.)

He starts by admitting that most people are skeptical that science can lead us to certain values; science can tell us what is, but not what ought to be. There is a old saying, going back to David Hume, that you can’t derive ought from is. And Hume was right! You can’t derive ought from is. Yet people insist on trying.

Harris uses an ancient strategy to slip morality into what starts out as description. He says:

Values are a certain kind of fact. They are facts about the well-being of conscious creatures… If we’re more concerned about our fellow primates than we are about insects, as indeed we are, it’s because we think they are exposed to a greater range of potential happiness and suffering. The crucial thing to notice here is that this is a factual claim.

Let’s grant the factual nature of the claim that primates are exposed to a greater range of happiness and suffering than insects or rocks. So what? That doesn’t mean we should care about their suffering or happiness; it doesn’t imply anything at all about morality, how we ought to feel, or how to draw the line between right and wrong.

Morality and science operate in very different ways. In science, our judgments are ultimately grounded in data; when it comes to values we have no such recourse. If I believe in the Big Bang model and you believe in the Steady State cosmology, I can point to the successful predictions of the cosmic background radiation, light element nucleosynthesis, evolution of large-scale structure, and so on. Eventually you would either agree or be relegated to crackpot status. But what if I believe that the highest moral good is to be found in the autonomy of the individual, while you believe that the highest good is to maximize the utility of some societal group? What are the data we can point to in order to adjudicate this disagreement? We might use empirical means to measure whether one preference or the other leads to systems that give people more successful lives on some particular scale — but that’s presuming the answer, not deriving it. Who decides what is a successful life? It’s ultimately a personal choice, not an objective truth to be found simply by looking closely at the world. How are we to balance individual rights against the collective good? You can do all the experiments you like and never find an answer to that question.

Harris is doing exactly what Hume warned against, in a move that is at least as old as Plato: he’s noticing that most people are, as a matter of empirical fact, more concerned about the fate of primates than the fate of insects, and taking that as evidence that we ought to be more concerned about them; that it is morally correct to have those feelings. But that’s a non sequitur. After all, not everyone is all that concerned about the happiness and suffering of primates, or even of other human beings; some people take pleasure in torturing them. And even if they didn’t, again, so what? We are simply stating facts about how human beings feel, from which we have no warrant whatsoever to conclude things about how they should feel.

Attempts to derive ought from is are like attempts to reach an odd number by adding together even numbers. If someone claims that they’ve done it, you don’t have to check their math; you know that they’ve made a mistake. Or, to choose a different mathematical analogy, any particular judgment about right and wrong is like Euclid’s parallel postulate in geometry; there is not a unique choice that is compatible with the other axioms, and different choices could in principle give different interesting moral philosophies.

A big part of the temptation to insist that moral judgments are objectively true is that we would like to have justification for arguing against what we see as moral outrages when they occur. But there’s no reason why we can’t be judgmental and firm in our personal convictions, even if we are honest that those convictions don’t have the same status as objective laws of nature. In the real world, when we disagree with someone else’s moral judgments, we try to persuade them to see things our way; if that fails, we may (as a society) resort to more dramatic measures like throwing them in jail. But our ability to persuade others that they are being immoral is completely unaffected — and indeed, may even be hindered — by pretending that our version of morality is objectively true. In the end, we will always be appealing to their own moral senses, which may or may not coincide with ours.

The unfortunate part of this is that Harris says a lot of true and interesting things, and threatens to undermine the power of his argument by insisting on the objectivity of moral judgments. There are not objective moral truths (where “objective” means “existing independently of human invention”), but there are real human beings with complex sets of preferences. What we call “morality” is an outgrowth of the interplay of those preferences with the world around us, and in particular with other human beings. The project of moral philosophy is to make sense of our preferences, to try to make them logically consistent, to reconcile them with the preferences of others and the realities of our environments, and to discover how to fulfill them most efficiently. Science can be extremely helpful, even crucial, in that task. We live in a universe governed by natural laws, and it makes all the sense in the world to think that a clear understanding of those laws will be useful in helping us live our lives — for example, when it comes to abortion or gay marriage. When Harris talks about how people can reach different states of happiness, or how societies can become more successful, the relevance of science to these goals is absolutely real and worth stressing.

Which is why it’s a shame to get the whole thing off on the wrong foot by insisting that values are simply a particular version of empirical facts. When people share values, facts can be very helpful to them in advancing their goals. But when they don’t share values, there’s no way to show that one of the parties is “objectively wrong.” And when you start thinking that there is, a whole set of dangerous mistakes begins to threaten. It’s okay to admit that values can’t be derived from facts — science is great, but it’s not the only thing in the world.

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180 Responses to The Moral Equivalent of the Parallel Postulate

  1. The Chemist says:

    This isn’t a surprise to me. Sam Harris has been trying to skirt moral relativism for a while now. Come on over Harris! The water’s just fine over here on the deep end of intellectual discussion.

  2. Sam Gralla says:

    You can’t convince a crackpot that relativity is right, and you can’t convince a neo-nazi that Hitler was a scumbag. But the vast majority agree relativity is right, and the vast majority agree Hitler was a scumbag. We make up phrases like “relativity is right” and “Hitler was a scumbag”; since most agree, we call these phrases “facts”.

    Where in your epistomology can you possibly distinguish between an “experiment”–which you say can produce objective facts–and everything else that might influence a person’s opinion, which you say can’t produce objective facts?

  3. wolfgang says:


    if you really believe in the many worlds interpretation, then you believe that the deterministic, unitary evolution of the wavefunction (of the universe) is all there is.
    There is nothing you can ‘decide’ or ‘change’ about anything.
    The placement of your personal experience in one of the possible worlds is nothing you can ‘control’ in any way.
    There is no debate between ought and is because is is all there is.

  4. James Wilson says:

    You write:
    There are not objective moral truths (where “objective” means “existing independently of human invention)…

    I read this as suggesting that you are a moral relativist, i.e. you don’t believe in universal values, only in subjective opinions of morality. Is that correct? If so, how do you reconcile this position with the concept of international human rights? Consider, for example, campaigns against slavery and female genital mutilation, where these practices occur in traditional cultures which fully approve of them. More generally, this has been an issue impacting the advocacy of women’s rights in countries where traditional values oppose such rights. Are these values somehow “Western” and thus basically arbitrary? Or are they universal human rights, and not just a matter of opinion?


  5. Maximus says:

    I frankly don’t understand why we even have to spend time discussing what Sam Harris says. I mean, who is Sam Harris except an ignorant popularizer that got famous writing an angry book against issues that he himself barely understands? On what possile authority does TED invite him to talk about morality? Is he a scientist? Is he a philosopher? No, neither. (yes, fine he JUST got his PhD. So what? Has he had any significant impact on the scientific community yet? No).

    He’s achieved his popularity cunningly jumping on the new atheists bandwagon, and by being the most populist, ‘folksey’ and offensive of the lot. As a matter of fact, I find amazing that intelligent people like Dan Dennett (or Sean Carroll for that matters) agree to have their name associated with him.

    [mind you, I am not a creationist in disguise, I am as atheist as Harris is. I just find absurd that we give authority to an absolute no-one like Harris]

  6. Hi Sean, interesting comments here, but I mostly disagree with you. By the way, Sam is soliciting criticism of his talk over at, so I’d suggest you link him to this post.

    Now, to the disagreement. It’s true that one will never be able to derive moral principles without making some assumptions, like axioms, at the base of everything. You are aware of this, stating “But what if I believe that the highest moral good is to be found in the autonomy of the individual, while you believe that the highest good is to maximize the utility of some societal group?” Clearly if you begin with different goals you will reach different conclusions about what are the most moral actions. And of course those conclusions should be informed by the facts of the matter – for example, there may be ways to enhance “the autonomy of the individual”, and if you’re wrong about what those ways are, then you will fail in your goal.

    But science is no different! Of course the Big Bang is based on facts, but it’s also an inductive generalization, and nothing in the facts tells us that any particular prediction of Big Bang theory is guaranteed to be right. At the base of science there are assumptions, for example, assumptions about how much confidence we should place in inductive generalisations. It’s mostly just an intuition, but that’s enough to get started, and we can make great progress once we stop worrying about the fact that our foundations are not absolutely set in stone. The foundations are solid enough to make progress, and we should not obsess too much over them. Your reaction to Sam’s talk seems to me to be equivalent to a radical sceptic thinking you’re wrong about the Big Bang because it’s impossible to have perfect knowledge.

    In ethics, I think the situation is much the same. Once you decide on a goal (for example, wanting conscious beings to be in more pleasant brain-states), the methods you should use for deciding what actions are moral are basically the methods of science. I see this as Sam Harris’s main important point, but there is another. Now, of course you could choose a different goal and then you would get different conclusions about what constitutes acting ethically. Here, I think Sam makes a second major point (that I also agree with): that wanting conscious beings to be in more pleasant brain-states is implicitly the goal of the vast majority of moral systems. Even religious ones: for example, a fundamentalist Christian who believes in a literal hell may be justified in quite radical acts here on Earth – and this would be right if it was expected to prevent future eternal suffering of conscious beings. The error here is scientific: the evidence for a literal hell is so weak that there almost certainly isn’t one. Also, people who advocate individual freedom, or strong communities, do so because they think it produces the best lives for people – not because it’s an end in itself.

    The foundations of ethics, and science, are not absolutely rock solid – but that’s okay. They’re solid enough to make progress. There is a place for intellectual hand-wringing about foundations, but that doesn’t mean that anything goes and that we may as well give up.

  7. The Chemist says:

    @James Wilson

    Ah, but there’s the rub! The short answer is, you can’t. It doesn’t mean it’s untrue. As a practical matter, you have to pretend that isn’t true in your day to day life, but moral relativism is inescapable. It’s kind of not a big deal, after all in our day to day lives we pretend that what we do in life matters- it doesn’t, but that doesn’t bother me.

  8. Tom says:

    A clearly stated point. Facts are facts, observables are observables. How one feels about them, or what kind of behavior you think is desirable, what kind of outcomes you think are desirable, are entirely relative and up to the individual actor.

    Far more discussions would be easier to have if one were to clarify that your argument was over the best WAY to get somewhere, or over the best PLACE to get to (the second being entirely subjective).

  9. Sean says:

    Brendon– I don’t think that’s a good analogy. As you say, we have to distinguish between choosing a goal and choosing the best way to get there. But when we do science we all basically agree on what the goals are — we want to find a concise, powerful explanation of the empirical facts we observe. Sure, someone can choose to disagree with those goals — but then they’re not doing science, they’re doing philosophy of science. Which is interesting in its own right, but not the same thing.

    When it comes to morality, there is nowhere near the unanimity of goals that there is in science. That’s not a minor quibble, that’s the crucial difference! If we all agreed on the goals, we would indeed expend our intellectual effort on the well-grounded program of figuring out how best to achieve those goals. That would be great, but it’s not the world in which we live.

  10. Bee says:

    According to Leibniz, we live in the best of all possible worlds. Ergo, what is ought and what ought is.

  11. Sean – I think there is more agreement on goals than you might think. All we need to recognise is that some states of existence are better than others, and that’s enough.

    We may disagree about how we order the states, particularly when it comes to details, but sometimes it’s just obvious. For example, it’s better to live with a loving family than to be held captive by a psychopathic torturer.

    There will also be a lot of states that are equally as good as each other, as far as we can tell. That also doesn’t detract from my point.

  12. abb3w says:

    Technically, what Harris is doing is pointing out that science can determine what IS the common element of all human OUGHT assessments. In that, he is correct.

    He then makes at least three errors thereafter: first, presuming that we OUGHT to use that as the primary bridge across the IS-OUGHT divide; second, neglecting to consider whether this common element is an exact expression, or merely a close approximation; and third, neglecting to consider whether this is a particular case of a more general problem.

    Attempts to derive ought from is are like attempts to reach an odd number by adding together even numbers.

    A closer comparison would be the production of an infinite ordinal by the addition of finite ordinals, because in a sense you CAN do that– the catch being, it requires being able to take an infinite ordinal number of steps in the first place. So, you can get an infinite ordinal… if you have an infinite ordinal. And when someone claims to have produced an infinite ordinal, you simply need to look for where the prior infinite ordinal was.

    However, the typical college graduate will find that a little obscure mathematically.

    It’s okay to admit that values can’t be derived from facts — science is great, but it’s not the only thing in the world.

    Exactly. Once you are playing around with what choices OUGHT to be made, it’s no longer science; it’s engineering.

  13. it’s because we think they are exposed to a greater range of potential happiness and suffering.

    I don’t think Harris is committing the is-ought fallacy here. He starts by assuming that we should alleviate suffering, and given that assumption he says science can then inform us of how to deal with that.

    I happen to agree with his assumption, but beyond that there is of course nothing but moral relativism.

  14. I’d also like to mention that I would be against trying to call this philosophy “objective morality”. It’s subjective – just like science – but subjective doesn’t mean capricious and unconstrained. :)

  15. Gratex says:

    Harris’ ideas are based upon empirical evidence – that most people need to feel that their moral decisions are based upon some external authority (thus outsourcing their accountability), and as such we can attempt to assert a scientific authority if our goal is to squeeze some more people out of the Dark Ages. Does it further the ideals of the scientific method to have parishoners of science, though? I doubt it. One could say that Harris is so caught up in his little war against the nutters that he’s become one of them.

  16. Lord says:

    You can’t derive ought from is, but most definitely what is affects what ought to be. What is not and can not be, can never be ought. Is informs ought.

  17. eukaryote says:

    Experiential states of conscious beings are data. Those experiences are part of concrete reality, and they can be assesed as to their inherent goodness or badness. Experiential states of suffering are inherently bad. How else could we define bad?
    If we make those assumptions, that suffering is concretely real, and that it should be minimized, then I don’t see why such an endeavor could not take the form of a scientifc enterprise.

  18. Reginald Selkirk says:

    Harris has a tendency towards black and white thinking which is on full display here.

  19. Leslie Haber says:

    Regardless of the logical and linguistic terms of the debate, Harris makes some very important points. First, he argues, impressively, that one person’s opinion may very well not be as informed, and therefore not as viable. Why does everyone have an equal voice in the call for ethical understanding? They shouldn’t.

    And secondly, while we do not have the full understanding of the consciousness and its functions, someday we will. That, as eukaryote notes, puts the realm of ethical behavior solidly in scientific territory.

    Unless we reframe the debate, we are lost in he said-she said, with an iron age book as our primary authority. Harris might not be absolutely correct, but the mere fact that he has started the discussion is valuable, and perhaps morally necessary.

  20. Carol Roper says:

    Hey Sean,

    Surprisingly to me, I disagree with you on this one.

    You said: In science, our judgments are ultimately grounded in data; when it comes to values we have no such recourse.

    I don’t agree here. We have lots of data which exemplifies assorted moral stances and I think we can most certainly make reasoned judgements based on them. Look at the blatantly obvious events like the Holocaust, Pol Pot, etc.

    You said: The unfortunate part of this is that Harris says a lot of true and interesting things, and threatens to undermine the power of his argument by insisting on the objectivity of moral judgments. There are not objective moral truths (where “objective” means “existing independently of human invention”), but there are real human beings with complex sets of preferences. What we call “morality” is an outgrowth of the interplay of those preferences with the world around us, and in particular with other human beings.

    I think it’s your qualification (where objective means existing independently of human invention) that seems to be the crux of the disagreement. If I thought that was correct, I’d agree 100% with you. It is patently absurd to presume an objective morality exists outside of human construct.

    But I don’t believe (at least I certainly didn’t hear it that way) that that is what Harris said at all, or even implied. Rather, I thought that his point was quite the opposite – that we can make objective moral analysis and decisions based on historical observation of situations and the obvious effects of those actions.

    I ‘heard’ his talk more as a reaction to the worn politically correct position that we have no right to judge anyone. Yes, it’s definitely a slippery slope when we engage in judging, but for humanity to progress, at some point we must pull up our pants and get to it.

    I believe there is considerable common ground throughout the world to do this. I don’t think it’s up to any individual, self-appointed group or self-nominated country to take on DOING anything about these questions, but a group representing all parts of the world (such as the concept of the UN) should indeed take this next step towards helping humanity. Yes, it’s a ‘goal’, but it is possible to conclude, via scientific methodology -(i.e. data analysis, for example) what has been considered by the majority to be ‘beneficial’ vs ‘harmful’ throughout human history, and subsequently, work to access the disclosed objective ‘beneficial’ for all. It’s scientific if one doesn’t preclude findings based on personal beliefs, but rather permits the data to speak for itself. Some obvious, objective goals that would likely emerge – elimination of pestilences and diseases, elimination of starvation, etc. We could also discover that what we believed would be a ‘benefit’ is not. Then we’d have a VERY subjective moral quandary!

    I didn’t understand Harris to be suggesting that the majority decide on who can marry, or dress codes, (though he was awfully miffed about the veils), but about the larger questions which, really ARE answerable using the scientific method. (In my non-scientist opinion. {grin})

    Or am I misunderstanding your objections?

  21. Steve Esser says:

    Hi Sean. I agree with Harris, and would put it this way. Morality and values are facts about first-person experiences of conscious creatures. So, right, they’re not completely “objective” on one reading of that term (i.e. objective=third-person facts). But I would contend that they are objective in relevant sense in that they are facts about nature, not opinions relative to a point of view. We can and should be able to investigate these experiences in the spirit of how science is conducted in other domains.

    The alternative is to cede first person experience as outside the domain of nature – that’s not what you mean to advocate, is it? I think there is a more general point here that restrictive views of naturalism (materialism) enable the persistance of old-fashioned dualisms and supernaturalisms.

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  23. Paul Stankus says:

    To Maximus @ #5

    Maximus, I notice that you haven’t cited any actual facts or evidence in your denigration of Sam Harris. Why, exactly, should anyone believe your statements, or concur with your judgements, that Harris is “ignorant,” that “he himself barely understands” the issues he writes about, or that he’s a “an absolute no-one”? Not that I have any particular brief for Harris, myself; I’m just pointing out that you’ve added no value in condemning him without showing any evidence beyond your own (anonymous) authority.

    Without either waving credentials or citing authorities, can you take a moment to explain, in plain, non-circular, and passably non-technical language, what is the case against Harris’ writings?

  24. Cody says:

    Wow, lots of good comments, and a very interesting and thought-provoking analysis Sean, thanks!

    I thought I agreed with Harris when I watched this the other day, but I didn’t pay close enough attention to know for sure. I agree with most of what you have written too Sean, as well as much of the comments here. Until I get home, and can re-watch Sam’s talk, I won’t really know if this is related to what he said or not.

    Anyway, here’s my two cents:
    As a moral relativist I figure the differences we have in morals are largely influenced by our environments, but from an evolutionary point of view there ought to be causal reasons why we tend to have the moral values that we have, and with that understanding we can make scientific statements about what morals people have (and why).

    I’ve been very interested (for quite some time now) in modeling the amount of cheating humans are willing to participate in by looking at a game theoretic model describing the cost and benefits of cooperation or defection. I imagine that a reasonably simple model could probably start to reproduce a society in which most people play by the rules, most of the time. This would be akin to describing the origin and dynamics of our morals nearly ab initio.

    I think the absolutist position I have developed with respect to my own moral relativism has provided me with a reflexive objection to any claim that science can provide us with morals, but when I consider how much science can tell us about our morals, where they came from, why we have them, and which ones we have and with what prevalence, etc., I begin to think maybe science does have a lot more to say about this… or at least more than I would have first suspected.

  25. Maximus says:

    Paul, my tones were perhaps too harsh, but I was simply pointing out the fact that I find quite amazing that someone like Harris must be taken as an authority on matters of ‘religion and secularism’ and on morality simply because he happens to vociferously ride the ‘new-atheist’ movement. He has no academic nor intellectual credentials whatsoever. This is a very general observation, regardless of the content of his claims. As for his ideas, I personally believe that he repetedly made claims regarding ‘religions’ (whatever that means for him) which border the irresponsible, and are at least ‘scientifically’ ungrounded. The best possible debunking of the intellactual credibily of Harris came some years ago from anthropologist Scott Atran (ok I am perhaps citing an authority here, but in this context, and for sake of brevity since i happen to agree completely with Atran, I think it is reasonable to do it) see here: [].
    Sean is right in saying that ‘morality’ is no science, but does that mean that we can give our time and attention (and hence implicitely invest with some sort of authority) to everyone that happens to have opinions about it?