The Science Behind What Makes Us Unique

by Michael S. Gazzaniga

Ecco, 464 pp., $27.50

It's a familiar comic scene. A man is searching for something under a street lamp. A passerby approaches:

"What are you looking for?"

"My keys."

"Where did you lose them?"

"Back over there."

"Then why look for them here?"

"The light is better here."

Academic experts--economists, lawyers, philosophers, theologians--often seem to have the same attitude: Whatever you need you can find in their corner, where all the light is. Supply and demand, legal regulation, the Categorical Imperative, Original Sin can explain everything. Perhaps no discipline is more likely to claim explanatory omnipotence and unique objectivity than science. Before the altar of science, all other disciplines must bow. And its high priests are evolutionary biologists and neuroscientists: Everything about us, ultimately, can be explained by natural selection and the brain.

Am I being unfair? Only a bit. For an exemplar of this attitude, take Michael S. Gazzaniga's new book, Human: The Science Behind What Makes Us Unique. Don't let the subtitle fool you; it's not as if "science" is one among many branches of knowledge that shed light on what distinguishes us. No, Gazzaniga thinks that we can put away philosophical inquiry, poetic rumination, and prophetic revelation: Recent advances in neuroscience are finally providing us with what Gazzaniga regards as real answers to life's deepest questions, which (like everything human) are ultimately, he is absolutely sure, about biology.

In reality, Gazzaniga and his colleagues overreach and under-deliver. This is not to deny that science is making amazing discoveries about human nature, and for understanding some of these, this book is quite helpful.

Director of the SAGE Center for the Study of the Mind at the University of California at Santa Barbara, and a member of the President's Council on Bioethics, Gazzaniga is an authority on neuroscience, especially split-brain research. In Human he offers a useful one-stop shop on the latest scientific findings, even if his endless name-dropping and hedging of claims with conflicting theories make for a cumbersome read and leave some of his own conclusions elusive. Trying, too, is his overly conversational style: "How can one little change do so much damage? Take a deep breath. Blow it out slowly. OK, now you're ready." With proper editing, the text could have been half as long as it is.

Gazzaniga's main aim is simple: to show how human beings can be "hugely different" from other animals despite having "all of these connections with the biologic world, and .  .  . in some instances similar mental structures." The differences are the result of many small brain developments eventually reaching a biological tipping point, what Gazzaniga calls "a phase shift." After a tour of our brain's hemispheres and lobes, cerebral cortex and neocortex, cerebellum and corpus callosum, Gazzaniga concludes that "the human brain is a bizarre device, set in place through natural selection for one main purpose--to make decisions that enhance reproductive success."

He similarly explains human practices like the arts, noting that we alone make music as such. "It boils down to this: .  .  . Sensations and perceptions that have adaptive value .  .  . often become aesthetically preferred." Admitting (because scientific research confirms) that "art can put a smile on your face," Gazzaniga lets us in on the secret: We are smiling "because our cocky brain is pleased with itself, because it is fluently processing a stimulus, but you don't need to tell the artist that."

For a study of human-to-human social interactions, he turns to evolutionary psychology, according to which social relationships "are merely by-products of behavior originally selected to avoid our being eaten by predators." We may distinguish "our 'meaningful' as well as our 'manipulative' social relationships," but he considers this a mere rationalization "generated by a process secondary to the real reason we fall into social groups." Our sociability is "deeply rooted in our biology not simply in our cognitive theories about ourselves." So too, in his view, are those very cognitive theories, and even cognition itself.

So it isn't surprising that Gazzaniga also uses biology to explain "the moral compass within." Where does our morality come from? While we might "like to think of ourselves as rational beings" able to reach timeless, objective moral truths, Gazzaniga argues that it is "our gut, our intuitive self, that first comes up with the judgment, and our rational self afterward tries to come up with the reasons" to justify prerational moral intuition.

Where do these gut intuitions come from? Although "until recently, all one could do was bat these ideas around without any concrete evidence," now "things have changed" and modern science shows that "we actually have hardwired ethical programming that has been selected for." You guessed it: Morality, like everything else, has been selected for its survival value.

Consequently, the incest taboo needs amendment. This gut instinct has been selected only because, on average, in the long run, it leads to reproductive success. But "if it were rational, then it would not apply to adopted or to stepsiblings." Gazzaniga, in technical terms, explains where this moral belief comes from: "We got it at the factory." He confidently concludes that "moral judgments are not completely rational," they amount to little more than "It feels bad: don't do it."

In fact, all kinds of moral norms lack a rational basis: "Why not dump your sick husband or wife and get a healthy one? That would be more rational. Why spend public money on the severely handicapped, when they will rarely be able to repay it?" In Gazzaniga's world, "a rational person would never go into partnership with someone else because of the high probability that the other rational person would cheat, because if the opportunity presented itself, there would be no rational reason not to."

Which is why Gazzaniga is glad that we don't live in a rational world: "Emotions solve the problem" by repelling us from perfectly rational activities like cheating, lying, and extramarital sex. He appeals to the crudest form of crass utilitarianism and equates its narrow calculations of self-interest--and only these--with being "rational."

Such disregard for any sort of philosophical reflection makes Human a disappointment. While Gazzaniga is a reliable guide on the facts of neuroscience and evolutionary psychology, his interpretations of the data and hasty dismissals of other disciplines of inquiry (especially philosophy) are fatal for the task he has set for himself: to understand humanity.

Gazzaniga's thoroughgoing physicalism, which motivates his reduction of human activities to the domain of the natural sciences alone, is unwarranted. To refute the opposing view that the human person has an immaterial aspect, he gives an evolutionary explanation for it, noting that children are "natural believers in essentialism." And that, presumably, is enough. If children believe something, it and all related beliefs must be evolutionarily determined and, therefore, false. We think this way only because "our brain processes have been selected over time."

But if Gazzaniga is correct about this, then his arguments are ultimately self-defeating. For if the brain's output is determined by blind evolutionary forces and has no necessary connection to objective truth, then his neuroscience is also unreliable. How does he know that the methods his brain leads him to use produce results that are true, and not just selected for reproductive success? And, for that matter, how can I assent to Gazzaniga's conclusions? If my brain happens to organize the "chaos of input" (Gazzaniga's term) differently from his, on what basis do we settle the dispute?

In fact, if our personhood can ultimately be explained by recourse to brain states, molecules, and smaller physical parts, then what freedom is left for an "I" to engage in the weighing and sifting of argument and counter- argument that makes up academic (including scientific) discourse? In explaining the science behind what makes us unique, Gazzaniga has explained away the "us." His evolutionary explanations undercut not only religion and traditional morality, but all rationality and free choice, including scientific theories and the very enterprise of conducting research to develop them.

The job for future neuroscientists is to affirm, with Gazzaniga, that the human person stands in continuity with other animals, in many respects. But also in radical discontinuity when it comes to mental life. If traditional philosophical arguments for the immateriality of the intellect are correct, then neuroscientists will need to wrestle with the possibility that our mental life is essentially immaterial, though thoroughly integrated with bodily organs like the brain.

Evolutionary psychology and neuroscience will still matter: If we're really psychosomatic unities, then our biology must be studied, as it helps provide the basis of our inclinations and intuitions and can, if dysfunctional, impede reasoning. But we must maintain that we can, by our freedom and intellect, move beyond such evolutionarily advantageous but immoral behaviors as, say, racist varieties of kin-group affinity.

"The science behind what makes us unique," as presented by Gazzaniga, is ultimately unilluminating. Gazzaniga is skilled at telling us which sections of the brain light up on the MRI machine under which circumstances, and which behaviors might have been selected to increase our reproductive potential, but he offers no guidance on what any of this means for living a human life. Should we do whatever helps our survival according to science? If not, to what standard do we appeal? And how is reasoning about these questions even possible if the mind is only the evolutionarily determined brain?

Some human phenomena simply cannot be reduced to synaptic firings. Gazzaniga explains all human phenomena in this way because that's where his training lies--and his lighting is best. But some human pursuits--for love, beauty, truth, goodness--are greater than the sum of their material processes. Rather than explain what it is to be human, Gazzaniga has explained it away. There is light beyond the street lamp of neuroscience, and beyond is where the keys to living a fully human life can be found.

Ryan T. Anderson is editor of Public Discourse: Ethics, Law, and the Common Good a new publication of the Witherspoon Institute of Princeton, N.J.

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