Neuroscience can often answer the obvious questions but rarely the interesting ones. Illustration by Leo Espinosa

Good myths turn on simple pairs— God and Lucifer, Sun and Moon, Jerry and George—and so an author who makes a vital duo is rewarded with a long-lived audience. No one in 1900 would have thought it possible that a century later more people would read Conan Doyle’s Holmes and Watson stories than anything of George Meredith’s, but we do. And so Gene Roddenberry’s “Star Trek,” despite the silly plots and the cardboard-seeming sets, persists in its many versions because it captures a deep and abiding divide. Mr. Spock speaks for the rational, analytic self who assumes that the mind is a mechanism and that everything it does is logical, Captain Kirk for the belief that what governs our life is not only irrational but inexplicable, and the better for being so. The division has had new energy in our time: we care most about a person who is like a thinking machine at a moment when we have begun to have machines that think. Captain Kirk, meanwhile, is not only a Romantic, like so many other heroes, but a Romantic on a starship in a vacuum in deep space. When your entire body is every day dissolved, reënergized, and sent down to a new planet, and you still believe in the ineffable human spirit, you have really earned the right to be a soul man.

Writers on the brain and the mind tend to divide into Spocks and Kirks, either embracing the idea that consciousness can be located in a web of brain tissue or debunking it. For the past decade, at least, the Spocks have been running the Enterprise: there are books on your brain and music, books on your brain and storytelling, books that tell you why your brain makes you want to join the Army, and books that explain why you wish that Bar Refaeli were in the barracks with you. The neurological turn has become what the “cultural” turn was a few decades ago: the all-purpose non-explanation explanation of everything. Thirty years ago, you could feel loftily significant by attaching the word “culture” to anything you wanted to inspect: we didn’t live in a violent country, we lived in a “culture of violence”; we didn’t have sharp political differences, we lived in a “culture of complaint”; and so on. In those days, Time, taking up the American pursuit of pleasure, praised Christopher Lasch’s “The Culture of Narcissism”; now Time has a cover story on happiness and asks whether we are “hardwired” to pursue it.

Myths depend on balance, on preserving their eternal twoness, and so we have on our hands a sudden and severe Kirkist backlash. A series of new books all present watch-and-ward arguments designed to show that brain science promises much and delivers little. They include “A Skeptic’s Guide to the Mind” (St. Martin’s), by Robert A. Burton; “Brainwashed: The Seductive Appeal of Mindless Neuro-Science” (Basic), by Sally Satel and Scott O. Lilienfeld; and “Neuro: The New Brain Sciences and the Management of the Mind” (Princeton), by a pair of cognitive scientists, Nikolas Rose and Joelle M. Abi-Rached.

“Bumpology” is what the skeptical wit Sydney Smith, writing in the eighteen-twenties, called phrenology, the belief that the shape of your skull was a map of your mind. His contemporary heirs rehearse, a little mordantly, failed bits of Bumpology that indeed seem more like phrenology than like real psychology. There was the left-right brain split, which insisted on a far neater break within our heads (Spock bits to the left, Kirk bits to the right) than is now believed to exist. The skeptics revisit the literature on “mirror neurons,” which become excited in the frontal lobes of macaque monkeys when the monkeys imitate researchers, and have been used to explain the origins of human empathy and sociability. There’s no proof that social-minded Homo sapiens has mirror neurons, while the monkeys who certainly do are not particularly social. (And, if those neurons are standard issue, then they can’t be very explanatory of what we mean by empathy: Bernie Madoff would have as many as Nelson Mandela.)

It turns out, in any case, that it’s very rare for any mental activity to be situated tidily in one network of neurons, much less one bit of the brain. When you think you’ve located a function in one part of the brain, you will soon find that it has skipped town, like a bail jumper. And all of the neuro-skeptics argue for the plasticity of our neural networks. We learn and shape our neurology as much as we inherit it. Our selves shape our brains at least as much as our brains our selves.

Each author, though, has a polemical project, something to put in place of mere Bumpology. (People who write books on indoor plumbing seldom feel obliged to rival Vitruvius as theorists of architecture, but it seems that no one can write about one neuron without explaining all thought.) “Brainwashed” is nervously libertarian; Satel is a scholar at the American Enterprise Institute, and she and Lilienfeld are worried that neuroscience will shift wrongdoing from the responsible individual to his irresponsible brain, allowing crooks to cite neuroscience in order to get away with crimes. This concern seems overwrought, copping a plea via neuroscience not being a significant social problem. Burton, a retired medical neurologist, seems anxious to prove himself a philosopher, and races through a series of arguments about free will and determinism to conclude that neuroscience doesn’t yet know enough and never will. Minds give us the illusion of existing as fixed, orderly causal devices, when in fact they aren’t. Looking at our minds with our minds is like writing a book about hallucinations while on LSD: you can’t tell the perceptual evidence from your own inner state. “The mind is and will always be a mystery,” Burton insists. Maybe so, and yet we’re perfectly capable of probing flawed equipment with flawed equipment: we know that our eyes have blind spots, even as we look at the evidence with them, and we understand all about the dog whistles we can’t hear. Since in the past twenty-five years alone we’ve learned a tremendous amount about minds, it’s hard to share the extent of his skepticism. Psychology is an imperfect science, but it’s a science.

In “Neuro,” Rose and Abi-Rached see the real problem: neuroscience can often answer the obvious questions but rarely the interesting ones. It can tell us how our minds are made to hear music, and how groups of notes provoke neural connections, but not why Mozart is more profound than Manilow. Courageously, they take on, and dismiss, the famous experiments by Benjamin Libet that seem to undermine the idea of free will. For a muscle movement, Libet showed, the brain begins “firing”—choosing, let’s say, the left joystick rather than the right—milliseconds before the subject knows any choice has been made, so that by the time we think we’re making a choice the brain has already made it. Rose and Abi-Rached are persuasively skeptical that “this tells us anything about the exercise of human will in any of the naturally occurring situations where individuals believe they have made a conscious choice—to take a holiday, choose a restaurant, apply for a job.” What we mean by “free will” in human social practice is just a different thing from what we might mean by it in a narrower neurological sense. We can’t find a disproof of free will in the indifference of our neurons, any more than we can find proof of it in the indeterminacy of the atoms they’re made of.