I grew up in a conservative Evangelical community and read some Marx, Bertrand Russell, and Voltaire as a teenager, so I was predisposed to sympathize with some of the argument (singular) of Sam Harris’s first two books, The End of Faith (reviewed here by John Haldane) and Letter to a Christian Nation, in which he explains, ad nauseam, the irrationality of religious belief and its attendant social ills. Harris believes irrationality is the primary impediment to human flourishing and that religion is the primary purveyor of irrationality in the world today.

Harris rides this hobbyhorse into his new book, The Moral Landscape: How Science Can Determine Human Values, which cites a number of examples of appalling cruelty and violence perpetrated in the name of religion—from honor killings in Pakistan to lynchings in the American South. But in The Moral Landscape these evils are mentioned mainly to remind readers what can happen when secular liberals leave morality to religion in the mistaken belief that science has nothing to say about morality. This abdication often goes along with the idea that moral propositions, unlike scientific theories, are merely the expressions of cultural biases produced by evolution. Harris is at his best in dissociating evolutionary psychology and neuroscience, his own area of expertise, from such blasé relativism.

“Questions about values,” Harris writes, “...are really questions about the well-being of conscious creatures.” This assumption, which philosophers call “utilitarianism,” is plausible. But Harris doesn’t give much consideration to philosophical alternatives: once you reject relativism, he suggests, you’re left with either secular utilitarianism or the revealed morality of religion. Religious morality, he concedes, is also concerned with well-being, but its concern is based on irrational expectations of an afterlife and is therefore worthless. Values, he writes,

translate into facts that can be scientifically understood: regarding positive and negative social emotions, retributive impulses, the effects of specific laws and social institutions on human relationships, the neurophysiology of happiness and suffering, etc.

Many social scientists are already working to improve the world by addressing questions like these empirically, and Harris clearly wants them on his side. He says that “science” should be “broadly construed as our best effort to form a rational account of empirical reality”; so construed, science includes not only physics, chemistry, and biology, but also disciplines like history.

Once we admit there are facts to be known about morality, we may begin to use deeper, more basic branches of science to discover these facts and adjudicate moral controversies. Thus, while Harris is careful to admit that acculturation plays an important role in determining how we conceive fulfillment, he thinks that it is, in principle, possible to understand this role neurologically and thereby determine, for instance, whether Muslim women are better or worse off in burqas. This would be a truly remarkable development. Unfortunately, the neuroscience that could answer this question doesn’t exist yet, and Harris admits that it might never exist. Thus, we get an IOU rather than an argument. Harris’s forthrightness about the inevitable difficulties and potential shortcomings of science is admirable, but I’m not convinced the sort of scientific discovery Harris awaits is possible, in principle or otherwise.

In any case, the promise of neuroscience fails to get his theory past the traditional objections to utilitarianism. One of these is that utilitarianism fails to provide a thorough, coherent account of human flourishing. Harris is confident, though not sure, that neuroscience will one day be able to isolate the neural coordinates of well-being. Now, it would be foolhardy to claim with confidence that neuroscientists will never be able to manipulate chemicals in the brain to produce such feelings as happiness, pleasure, and fulfillment, but one may wonder whether this would produce real well-being. Harris claims that “human well-being entirely depends on events in the world and on states of the human brain,” but this is annoyingly vague. Obviously, he means to suggest a very complex, interactive process in which the brain is shaped by our surroundings while also determining our reaction to them. The project is to discover the kind of upbringing that cultivates brains most fit for fulfillment and then to put those brains into the kind of environment that will fulfill them. But what if we could create these neural states without worrying about the real-world conditions we associate with the good life (as in the movie The Matrix)? Harris cites some neurological evidence that we “like” true statements and “dislike” false ones, but surely the brain’s response to truth and falsehood is also in principle manipulable. Would it matter that we were really slaves as long as we felt like we were in utopia? I think most of us have moral intuitions that would deem such a situation repugnant, but Harris doesn’t address these intuitions.

And this isn’t the only problem Harris fails to address. Should you throw a switch causing a runaway trolley to kill one person instead of five? If you could cure cancer by sacrificing an innocent, should you? These questions get at another classic objection to utilitarianism: Does every person have inalienable rights, or may we sacrifice the well-being of individuals for the highest average well-being of the group? Can neuroscience answer such a question? I don’t believe so. The neural well-being Harris wants to discover is, like all utilitarian conceptions of well-being, ultimately an abstract good attributed to an abstract system vaguely modeled on a human individual and not readily applicable to a real society. Although we may understand perfectly the neural consequences of each alternative, it isn’t a question of science whether we should, or can, accomplish good by doing evil.

The most real neuroscience we see in the book comes in a question-begging argument against biologist Stephen Jay Gould’s claim that religious statements and statements about the physical world derive from “nonoverlapping magisteria” and should therefore be evaluated differently. Harris seems to think that by showing similar patterns of blood-flow in brains considering either kind of statement he can prove the two kinds essentially similar. This is materialism at its crudest, scientism at its most pretentious.

Harris gives us a lot of anecdotes about squishy secularists who can’t bring themselves to make common-sense moral judgments—for example, cultural anthropologists who refuse to condemn female genital mutilation “objectively.” In his review of The Moral Landscape in the New York Times Book Review, Kwame Anthony Appiah pointed out that, according to a recent survey, two-thirds of academic philosophers consider themselves moral realists rather than relativists. The cowardly moral relativism that Harris decries isn’t quite as rampant as he suggests. He presents his new book as a sort of therapeutic intervention in the culture wars, but if secular liberals were mostly spineless relativists, why would they have involved themselves in such a war to begin with? The evidence available in any newspaper indicates, unsurprisingly, that there is no lack of moral certainty on either side of the culture wars.

Harris helpfully reminds us that the fact that the Osama bin Ladens of the world disagree with the prevailing liberal consensus doesn’t mean that morality is agent-relative any more than the fact that some Amazonian tribe still believes the sun revolves around the earth means that our scientific consensus about the solar system is culture-relative. Fair enough, but, as the culture wars show, there remain large gaps in the liberal consensus. To the extent that we still have genuine doubts and disagreements about morality, it isn’t clear that the speculative neuroscience Harris offers will help us much. And to the extent that there is consensus about morality, it isn’t clear that we need its help.