The scientific understanding of humans as physical creatures has progressed in leaps and bounds during the last four centuries. Its successes in comprehending musculature, circulation, the nervous system and the brain, digestion, cellular chemistry, genes, and the like, as well as the sources and progression of diseases that beset human existence, is astounding. Yet the “science of man,” as David Hume put it—understanding human beings as human beings, both individually and collectively—has been something of an embarrassment.
And it is one that persists. Hume’s own effort “to introduce the experimental method of reasoning into moral subjects”11xThe subtitle of Hume’s A Treatise of Human Nature, published 1737–40, is Being an Attempt to Introduce the Experimental Method of Reasoning into Moral Subjects. to give but one example, has been revitalized in recent decades by the new moral science, really a congeries of sciences that includes sociobiology, positive psychology, and various neurosciences. But the new efforts to find a strictly physicalist explanation of humankind’s moral dispositions and decisions—to reduce them, for example, to functions of neurochemistry—fall as far short as Hume’s did. No one would deny that moral thinking involves some grounding in our physical being as adaptive organisms developing, surviving, and reproducing in an environment. But is that it? That would be akin to saying that Martin Luther King Jr.’s “I Have a Dream” speech was a function of King’s lungs pushing air through the vocal folds in the larynx (and that its reception among his listeners was a function of an elaborate combination of neurons encoding information into the auditory cortex). All perfectly true, but utterly banal, because it tells us nothing about what makes something binding or compelling, beautiful and inspiring—nothing about those things, in other words, that make King’s speech a singular, and signal, human event.
Charles Darwin and his heirs are largely behind the new reductionist project. Darwin’s bold idea, however flawed in its particulars, remains one of the great achievements of science, and those who have followed in his footsteps have come some distance in correcting and refining the original theory. Yet what Darwin and neo-Darwinians achieved was rooted in a concern with continuities among species, in showing how human beings evolved from animal predecessors. Among later Darwinians in particular, this concern led to the conviction that human beings share the same essential nature with other species. The evolution from anthropoid to human was simply a function of the contingencies of adaptation and survival needs within different environments. This increasingly exclusive focus on biological similarities tended, on the one hand, to fold the human being entirely within the continuum of the animal order and, on the other hand, to minimize, downplay, or ignore altogether the distinguishing characteristics of the human species.