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Evolution and Ethics
The publication in 1975 of Edward O. Wilson's Sociobiology provoked a great controversy. Our deepest intuitions of right and wrong, Wilson asserted on the first page of his book, are guided by the emotional control centers of the brain, which evolved by natural selection to help the human animal exploit opportunities and avoid threats in the natural environment. Ethics is a branch of biology. The publication last year of Wilson's Consilience renewed the controversy as he continued to argue for explaining ethics through the biology of the moral sentiments.
Wilson's critics have warned that his reductionistic explanation of human ethics as a mere expression of animal impulses promotes a degrading view of human life. Some of his Christian critics have explained this as an inevitable consequence of a scientific naturalism that denies God's moral law as the supernatural ground for our sense of right and wrong. And yet I think Wilson's position is much stronger than it might seem at first glance. Indeed, the full strength of Wilson's Darwinian ethics becomes clear only when it is seen as a form of ethical naturalism that belongs to a tradition of natural law reasoning that is compatible with Christian theology.
The biological character of the natural moral law is suggested by a famous remark by Domitius Ulpianus, an ancient Roman jurist: "Natural right is that which nature has taught all animals." As quoted at the beginning of Justinian's Institutes, this remark entered the tradition of natural law reasoning, and it was cited by Thomas Aquinas when he explained natural law as rooted in "natural inclinations" or "natural instincts" that human beings might share with other social animals. Adam Smith continued this tradition of thought in explaining ethics as expressing the moral sentiments of human nature. As influenced by Smith's ethical theory, Charles Darwin explained the moral emotions as manifesting a moral sense rooted in the biological nature of human beings as social ...