Philosophers of mind these days don’t usually have much to say one way or the other about religion. This is because most of them think that a complete inventory of what there is in the world yields only physical entities (they are physicalists), and that there are no supernatural entitites—no gods, no God, no demons, no angels (they are naturalists). These commitments make them likely to judge religious supernaturalism and dualism false and therefore without philosophical interest, should they get around to thinking about the matter at all. But in this engaging and lucid book, Owen Flanagan, a philosopher of mind at Duke University, shows that it is possible to be both a neurophysicalist and to take religion half-seriously. He gives a lot of mostly approving words to Buddhism of the Tibetan Gelug variety, and has interesting asides on Catholicism, too, though of a more negative kind. He pays attention to these things because he wants to provide a physicalist account of what it is to be human, which does not rule out questions about meaning and purpose. And he finds Buddhism especially useful for this task.

But if you’re a naturalist and a physicalist, how can you reasonably talk about meaning without relapsing into talk of mysterious nonphysical entities like God, demons, thoughts, and souls? This is the really hard problem of the book’s title. The answer, according to Flanagan, is “eudaemonistic scientia,” which means knowledge of how human beings flourish. We are, Flanagan says, meaning-makers who need to be encouraged to see our lives as “psycho-poetic performances,” and to figure out how to perform them better. He develops this answer into a naturalized, empiricist, and physicalist version of Aristotelian-Thomist virtue theory, with a top-dressing of Gelug Buddhist psychology.

We are, Flanagan thinks, beings designed by Mother Nature (that is, by evolution) to be animals of a meaning-seeking sort. Furthermore, empirical study shows that there are deep transcultural commonalities in the patterns of human life that are supposed to contribute to flourishing, on the one hand, and those that are supposed to effect damage, on the other. It turns out, in Flanagan’s view, to be no harder in principle, even if a little trickier in practice, to discern what a flourishing human being is like than it is to discern what a flourishing gladiolus is like. Knowledge of this kind (about humans, not gladioli) is eudaemonistic scientia. It is knowledge of the kind of being each of us is, and of how we flourish or fail to. And it is knowledge, with just as good a title to that name as what neurologists tell us about what goes on in our brains.

Flanagan thinks our flourishing or lack of it is to some extent under our control. We can and do deliberate about possible futures for ourselves, and these deliberations are choices of a sort. They are neuronal states that affect such deliberations in complex ways, and in that physicalist sense we are free to choose and thus to have an effect on our futures. Performing such choices—and living with their consequences—is what it is to make and discover meaning. On Flanagan’s view, we are all faced with a hypothetical imperative: If you want to flourish, here are the patterns of life you ought to follow. He is not shy about offering norms, even if he is rather abstract about their content.

What’s interesting about Flanagan’s project is that he wants to carry it through as a neurophysicalist. That is, he thinks that every first-person mental event (seeing blue, enjoying Brahms, fearing death) “is some physical event or other,” but has among its essential features “a certain feel.” According to Flanagan, these feels (or qualia, as philosophers like to call them) are as real and as much part of you as are the patterns of neuronal firing upon which they supervene and which are their necessary and perhaps sufficient conditions. Phenomenology, the descriptive-analytical science of these feels (of what it seems like to you to be you) and neuroscience, the science of the brain and its states (of what’s going on in your brain whether you know it or not—usually not) must, on Flanagan’s view, be held together, neither being reduced to the other. Phenomenology describes what makes us interesting to ourselves; neuroscience explains what causes us to find ourselves interesting. The two together offer a complete account of what it is to be a human person—and, when coupled with evolutionary biology, of what it is to flourish as such.

These phenomenal feels, which we might as well call mental states (Flanagan sometimes does), are not, in his view, nonphysical, even though they seem so to us. He is sure of this because he thinks the only things capable of entering into causal relations are physical, and that mental states do enter into causal relations—as, for example, when we choose a course of action that contributes to our flourishing. The causal inefficacy of the nonphysical is axiomatic for him: he takes it to be a nonnegotiable finding and premise of good science. And this in turn means that although he takes consciousness to be real, he understands it to be just the characteristic way in which brain states appear to animals like us. No doubt the brain states of dogs appear very differently to them, and it is unlikely that the brain states of frogs appear to them like anything at all. But for us, the appearances are complex and fascinating, which is what makes possible the psycho-poetic drama.

Let’s allow all this for the moment. If we do, neuroscience has offered a large promissory note: that one day we will know both how, causally speaking, brain states deliver mental states; and what, in detail, are the correlations between particular brain states and particular mental states. We know, Flanagan admits, nothing about the former and only a little (though much more than we used to) about the latter. But hope is after all a virtue, and so why not permit the neuroscientists theirs? If we do, then we can have an entirely naturalized virtue theory, to which Buddhist psychology, appropriately tamed and declawed (both these are Flanagan’s images: he doesn’t like the versions of Buddhism that affirm rebirth or the possibility of disembodied minds), can act as a good and faithful servant. And that means we can have meaning in an exclusively material world. We can have a richly normative understanding of what it is to flourish as a human animal.

Flanagan explicitly argues that his view is not compatible with Catholic Christianity, which he takes to be a problem not for him but for Catholicism. This is principally because Catholic doctrine asserts both that there are nonphysical entities, and that they can enter into causal relations with physical ones. Both views are axiomatically false for Flanagan. According to Catholic teaching, human beings cannot be entirely explained in exclusively physical terms. More fundamentally, the entirety of the physical cosmos is created ex nihilo by a God who is not himself physical. Flanagan is confident that no one has ever made any sense of these ideas.

But here he has some work to do. The only accounts of causal interaction between physical and nonphysical entities with which Flanagan seems to be familiar belong to early modernity, with Descartes as the principal example and whipping boy. Flanagan is right that such accounts do not work, but they are not the only ones available. Such causal accounts, when applied to God, treat him as one more being in the world—Superman without a body, a local idol—who intervenes in the world’s causal processes in some mysterious nonphysical way. But this is not Catholic teaching. The church teaches that God is not a being in the world but rather the one in whom all such beings participate. He is creator and redeemer of the world, where “world” means all that is not God. This means that God is the answer to the two fundamental questions of why there is anything physical at all, and (Flanagan’s really hard question) what the purpose—end, goal, meaning—of each particular being is. Science refuses the first of these two questions, and when it answers the second, it does so in a truncated way. A more complete answer to the second question can be had by using the Aristotelian four-cause schema (material, formal, final, efficient), according to which God serves as the beautiful lure (the final cause) toward which, knowingly or not, we all tend.

Flanagan’s own account of how human beings make and find meaning in a material world ought—and, I suspect, would, were it not for his physicalist commitments—dispose him toward accepting both final causes and the immaterial reality of qualia. This would permit him to understand human persons as “hylomorphic,” psychophysical unities. Final-cause talk is a technical version of purpose-talk—a ratcheting-up of that kind of talk to a more precise conceptual level. It specifies what it is to be drawn by the beauty of convenientia—of what is fittingly appropriate to the creatures we are—and does so with a richness and precision unavailable to Flanagan. And Flanagan’s own position already suggests the possibility that the mental events he understands to supervene upon brain states might not be accountable in exclusively physical terms. If he were to make these moves, he could have all the neuroscience he wants together with a much richer account of what it is to be a sentient being capable of contributing to, or undermining, his own flourishing. He is held back only by physicalist dogma, which I suppose is a comforting faith, but scarcely one becoming to a thinker.