According to a prominent tradition of Western thinking, morality is a thin overlay covering human savagery. Human beings are bestial by nature and ethical codes are curbs on their brutish instincts that enable them to live together in relative peace. Morality is a restraint on natural human behavior. At the same time it is believed to be uniquely human. Only humans possess the intellectual powers that are needed to repress natural impulses, and so only they can be moral.
Though this view can be found in many schools of thought, secular as well as religious, it is hard to spell out in any coherent fashion. If morality is a system of rules for the suppression of beastly behavior, where does it come from, and why have humans accepted it? How was it devised and imposed? Such questions are not easily answered, but when morality is assessed as it often is today according to some versions of Darwinian theory, the notion that it is a human construction without roots in our animal nature faces difficulties that are insoluble. If Darwinian theory is sound, morality in humans results at least in some part from evolutionary processes, and when they act as moral beings humans are displaying capacities they have in common with some other animals. Rather than suppressing their instincts, they are behaving naturally.
To view morality as a fetter on animal instincts is to think of it in pre-Darwinian terms, but curiously some of the most ardent Darwinians have also seen it in this way. As a result of his indefatigable defense of Darwinian theory the British biologist T.H. Huxley was known as “Darwin’s bulldog,” but he held that moral life was a struggle to combat nature—a view that left morality hanging in mid-air, without any evolutionary explanation, as a kind of human protest against the cosmos. In our own time Richard Dawkins has reaffirmed the Huxleyan position, concluding his book The Selfish Gene with the declaration: “We, alone on earth, can rebel against the tyranny of the selfish replicators.” A problem with this view is that it assumes a discontinuity between the biologies of humans and other animals that Darwin did not recognize. As Darwin wrote:
Any animal whatever, endowed with well-marked social instincts, the parental and filial affections being here included, would inevitably acquire a moral sense or conscience, as soon as its intellectual powers had become as well developed or nearly as well developed, as in man.
Darwin accepted that humans have a natural capacity for morality that has precursors in other animals. For example, he argued that the social instincts that form the “prime principle” of man’s moral sense can be found in monkeys, pelicans, and dogs, among other animals. Huxley rejected Darwin’s view and so it seems does Dawkins; in doing this they are in line with much modern philosophy in which there is a widespread resistance to any attempt to link moral behavior in humans with the behavior …