The Myth of the Great Divide

Science is descriptive. It tells us what is the case. All matters normative are found within the confines of philosophy. The human sciences can tell us about the content and evolution of our moral practices. But only philosophy can tell us what our moral practices should be. Psychology can tell us how we reason and come to believe what we do. But only philosophy can tell us how we ought to reason and what we are justified in believing.

This week I’ll argue that this is a myth, the Myth of the Great Divide.


Here’s a worry about the Great Divide: Psychology is full of normative research. Psychologists have argued that human reasoning is in some respects unreliable (e.g., Kahneman & Tversky; Paul Meehl). But psychologists don’t stop at the Great Divide. They make normative judgments. They disagree with each other and with philosophers about these judgments and about the nature of rationality. And they offer prescriptions about how we might reason more rationally.

The past two decades have seen an explosion of psychological research into happiness and well-being. Positive Psychology is full of theorizing about these normative categories and prescriptions about how to promote happiness and well-being


Proponents of the Great Divide will be unimpressed. The Great Divide, they’ll say, is maintained by an evidential divide. Philosophers and psychologists appeal to different sources of evidence when they study well-being (or rationality). Evidence for the psychologist involves observation and experiment; for the philosopher, intuitions.

Let’s begin our philosophical investigation by getting some intuitive purchase on well-being. Suppose I do something that makes your life today better for you than it was yesterday. You have greater well-being. But what is this well-being you have more of now? Are you happier? More satisfied? Have you gotten more of what you wanted in life?

To figure this out, the proponent of the Great Divide tells us to build a theory based on our intuitions. I’m not going to try to define intuitions. But there are cases that philosophers agree are important to the status of theories of well-being. Intuitions include the well-being judgments we make about those cases.

Here’s a weird thing, though. There’s quite a lot of intuitive disagreement among philosophers about those cases.

The Experience Machine. One person is genuinely engaged with the world and another is hooked up to a machine feeding electrical impulses into her brain. They have exactly the same experiences. Do they also have the same degree of well-being?

Hedonism says that your well-being is a function of the balance of your pleasure over your pain. It’s the James Brown (“I feel good!”) theory of well-being. For the hedonist, the twins have the same level of well-being. Many philosophers have the opposite intuition.

Remote Desires. Remote desires extend in time and space beyond our ken. Examples include the desire for posthumous fame, the desire for a stranger to flourish, or the desire for some distant future scenario (functional jet packs by the twenty-fourth century). If one of these remote desires is satisfied without you ever knowing it, does that boost your well-being?

Desire theories hold that well-being involves getting what you want, usually on the assumption that you’re properly rational and informed. It’s the Mick Jagger (“You can’t always get what you want”) theory of well-being. While the hedonist’s intuition is that remote desires are irrelevant to well-being, desire theorists have a surprisingly wide range of intuitions about remote desires. (For citations, see TGL, 27-8.)

The Thriving Wicked. Josef is a wicked man who enjoys inflicting pain on others. He lives in a wicked culture where inflicting pain on a minority is endorsed and rewarded. Josef lives a long life of comfort, pleasure, and success. Although Josef does not deserve a high degree of well-being, does he nonetheless have a high degree of well-being?

The gist of Aristotle’s view is that well-being involves having a virtuous character that promotes your flourishing – an active, healthy engagement with the world. It’s the Chuck Berry (“Johnny B. Goode”) theory of well-being. The Aristotelian thinks Josef doesn’t have a high level of well-being. Many philosophers have the opposite intuition.


The traditional approach has led to rampant theoretical dissensus. Peruse the philosophical literature on well-being and you’ll find a diverse smorgasbord of theories from which you can select the one that best fits your intuitions. Profound disagreement isn’t a temporary aberration that will resolve itself with more time and study. It’s the entirely predictable result of an approach that tells us to build theories that capture our intuitions despite the fact that we have deep intuitive disagreements. And yet the traditional approach dominates the philosophical landscape. Frankly, it has not had enough success to deserve the hegemony it enjoys.

But you can’t beat something with nothing. So next time, I’ll suggest something else.


  1. Hmm. Isn’t medicine normative? Would anybody say that medicine ought to be a branch of philosophy?

    Framing this point more generally, it seems to me that most areas of science are considered to have theoretical and applied branches, and that the applied branches are usually normative to some degree. It doesn’t seem likely that many people would confuse applied science with philosophy.

    Best regards, Bill

    • Michael Bishop

      Thanks for your comment, Bill. I think defenders of the Great Divide will want you to say more about the sense in which you think these applied areas of science are normative. Let me offer 2 suggestions:

      (1) To apply a normative theory (e.g., utilitarianism) to a set of facts, we’ll often need science because it’s the best source of evidence about those facts. This is consistent with the Great Divide because the empirical facts don’t count as evidence for the normative theory. You’re just applying the theory to the facts. (This isn’t what you seem to mean, though.)

      (2) Sometimes an engineer or a doctor will start with a goal (build a bridge from A to B, place a stent in the carotid artery) and try to achieve that goal in an elegant, efficient manner. Defenders of the Great Divide will grant that this “efficiency” sense of normativity pervades science. But this “efficiency” sense leaves open the question of whether this goal is a good one. If you press this normative question, you might soon find yourself making the sorts of normative claims the defender of the Great Divide thinks are on the philosophy side of the barrier.

  2. “Normative”, as I understand it, means something like “establishing, relating to, or deriving from a standard or norm”. In medicine the norm is “health”. Health is considered better than illness, and the good life is a life of maximum health.

    Actually all the issues in psychology have counterparts in medicine. There are disputes about how health should be defined; most doctors, however, take an “I know it when I see it” attitude. There is a school of “positive medicine” arguing that doctors should devote more effort to promoting good health rather than just trying to cure illness. Positive medicine actually preceded and to some degree motivated positive psychology.

    Of course the issue of defining health has a strong philosophical component, but you will have to look far and wide to find a doctor who is willing to allow philosophers to tell her what health is.

    Many other applied sciences are not as obviously normative as medicine, but most of them, I think, make use of some sort of implicit standard of goodness.

    • Michael Bishop

      It might turn out we’re on the same side, Bill. I’m not sure. Here’s my suggestion: See where I go with well-being and Positive Psychology. You can tell me if you think there are parallels in medicine. If there are, well, the more breaches in the Great Divide, the better.

  3. Alan Mattlage

    Mike, you write, “But psychologists don’t stop at the Great Divide. They make normative judgments. They disagree with each other and with philosophers about these judgments and about the nature of rationality. And they offer prescriptions about how we might reason more rationally.” I suppose this makes the “Great Divide” trivial, but isn’t this when psychologists stop doing psychology? I would think that noting the Great Divide is merely a way to mark a difference between the main intent of different disciplines or perhaps two different activities or uses of language. One can accept the divide but recognize that not much of interest can be said without making claims on both sides of it.

    • Michael Bishop

      Hi Alan! Thanks for your comment. You’re suggesting we view the descriptive-normative divide as a “useful disciplinary boundary” rather than a Great Divide. And that’s sort of how I view it. But the real issue is an epistemological one: Can science serve as substantive source of evidence for a normative theory?

      If you don’t think so, then I think you’re committed to the Great Divide: Science on one side attending to observation and experiment. Philosophy on the other side attending to intuition. Of course, the Great Divide doesn’t bar scientists from using normative categories in their research. But whether they’ve used the right normative categories depends on the dictates of intuition-based philosophy. No empirical finding can be evidentially relevant to normative theorizing.

      It is this view that I’ll be challenging tomorrow. And when I’m done, I hope you’re still with me – viewing the normative-descriptive distinction as a mere disciplinary boundary, not a deep epistemological divide.

      • Alan Mattlage

        Very good. This is a helpful clarification. The interesting question is whether we can infer moral claims from empirically established facts alone.

        • Michael Bishop

          Actually, Alan, in the next post (now available) I argue for an inclusive approach to the study of well-being, one that takes as evidence both intuitions and empirical results. I don’t think one can infer a good theory of well-being solely from the science of well-being. But I do think a good theory of well-being will organize, unify and make sense of the empirical research on well-being *and* it will (mostly) vindicate our intuitions about well-being.

  4. Anon

    I’m rather surprised by the framing of the debate.

    For example, you say that “proponent of the Great Divide tells us to build a theory based on our intuitions.” It seems to me that the overwhelming majority of history’s ethical philosophers are proponents of the Great Divide, even if they only become explicitly so after Hume.

    But it also seems to me that building a theory based on intuitions is a distinctive feature of 20th and 21st century ethical philosophy (e.g., trolleyology). My impression is that the foundational figures in ethics (Plato, Aristotle, Hume, Kant, Mill) try to the best of their ability, with varying degrees of success, to minimize intuitions in their ethical systems and, where they appeal to them, give reasons for those intuitions.

    So, perhaps I’m wrong, but I would associate proponents of the big divide with the *rejection* of the centrality of ethical intuition. Or more generally, I see it as difference between historical ethics (big divide, anti-intuition) and contemporary ethics (no divide, intuitionist).

    For example, trolleyology begins with the assumption that we all share some kind of consequentialist intuition that we should maximize happiness and minimize suffering, but that our unclear conception of what this is and how it is achieved leads to contradictory intuitions. The job is not to assert, found, or justify basic ethical norms (human flourishing), since it works on the assumption we already share them, but to clarify them, so we follow them consistently. It then makes the Great Divide irrelevant. We don’t have to derive an ought from an is, since we already agree on the ought. And it’s very conducive to a scientific approach to ethics, since science can best tell us what flourishing is and how to maximize us.

    Again, that may be wrong, but is your framing the obvious or accepted one? Would most ethical philosophers pair big-dividism and ethical intuitionism?

    Whether this framing is important seems relevant to the further implications of your post. You point, for example, to “an explosion of psychological research into happiness and well-being.” To my mind, this leads to an intuitionist ethics. Ethical intuition says I should pursue my and others well-being, and well-being is a matter of fact, so there’s no ought/is problem.

    But of course, the ought/is problem is that intuitions can be false. So how do I justify the claim that I “ought” to pursue my well-being when many self-destructive people don’t want to, or that I “ought” to pursue others, everyone’s, the majority’s, or the deserving’s well-being, when most don’t want to?

    • Michael Bishop

      I think the way most moral philosophy has been done for the last century or so has presupposed the Great Divide. In debates over well-being, for example, the only substantive evidence philosophers typically consider is their intuitions about well-being, both general and specific. The specific intuitions (about cases, e.g., the experience machine, the grass counter) play especially prominent roles. I think the same basic point holds for a lot of moral theorizing for the past century or so.


      I interpret your reading of contemporary moral theorizing to be influenced by experimental philosophy, which studies people’s intuitions empirically. So in some sense, X-phi has one foot on each side of the Great Divide (intuition, science). And so one could take X-phi to be a “no divide, intuitionist” approach to normative theorizing. But I think that’s too quick.

      I could have told a different story this week, one focused on X-phi and the challenge it faces from the Great Divide: “If X-phi is trying to figure out the mechanics of moral judgment, fine. That’s an empirical, scientific project. But then X-phi isn’t answering any normative philosophical questions. X-phi isn’t, for example, telling us what we *should* do in trolley problem cases. For that, you need a moral theory. And you build a moral theory by appealing to the evidence of moral intuitions, both specific and general.”

      I think that’s a pretty powerful argument. I don’t buy it. But it’s powerful. Some philosophers have tried to bridge the is-ought gap with debunking arguments: once you understand the process by which you came to have your moral judgments (the evolutionary process, the psychological process, or both), you won’t endorse them as true any more. These arguments are controversial.

      A classic X-phi move is to throw the evidence of intuition into doubt by showing there’s something wrong with it (e.g., intuitions are culture-bound or easily manipulated). Again, these arguments are controversial.

      Both these moves, though, lead to negative conclusions. They suggest that there’s something wrong with the theories and arguments proposed by traditional (intuition-driven) philosophy. But they don’t seem to offer positive theories.

      The inclusive approach offers a way to breach the Great Divide that produces positive theories that aren’t based solely on intuition – at least when it comes to well-being. Can something like this approach be modified to work for normative categories beyond well-being? I think so. (As I note in a post and in TGL, Kornblith applied something much like the inclusive approach to knowledge.)


      You say that X-phi studies of trolley problems start with “the assumption that we all share some kind of consequentialist intuition that we should maximize happiness and minimize suffering, but that our unclear conception of what this is and how it is achieved leads to contradictory intuitions.”

      One way to read this is as an attempt to breach the Great Divide by assuming that X-phi builds a moral theory by starting with consequentialism and then trying to clear up “our unclear conception of” maximizing happiness and minimizing suffering. Perhaps that’s not what you meant. But whatever the role you think this assumption is playing in trolleyology, I don’t read X-phi as making this assumption. One can interpret your assumption as a normative or a descriptive claim.

      If you interpret it as a descriptive claim, I don’t think it’s true. A large share of X-phi is addressing a straight empirical question: What are the mechanics of moral judgment? I don’t think that X-phi starts with the assumption that our moral judgments are driven by consequentialist principles – even judgments about trolley problems. (Consequentialism I take to be the view that the moral status of an action is determined *solely* by its consequences.) In fact, I think X-phi is going to find that the drivers of our judgments about trolley problems are not purely consequentialist. (But let’s shelve that issue.)

      If you read the claim as a normative claim, it’s not something you can just assume – unless you can explain why the deontologist doesn’t get to defend her theory in the same way. Does the consequentialist give the right answer in all trolley problems? I don’t think X-phi starts by assuming that the answer is yes, that consequentialism is the correct theory about the morality of trolley problems. You’d need some pretty serious arguments to get that conclusion. And you’d have to overcome the challenge of the Great Divide.

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