Dennis Krebs’ excellent overview of evolutionary moral psychology succeeds in celebrating Darwin as source for understanding and appreciating ethics.

One thing is clear. “Darwinian ethics” has a bad ring to it. To mind comes Social Darwinism, eugenics and the rest.
Indeed, audiences today are all too familiar with the “Darwinian” assumption that we are naturally governed by selfish motives. Lesser known is Darwin’s own view on the matter. In a letter to a friend, he wrote:
“I demur to your saying … that animals are governed by selfish motives! Look at the maternal instincts & and still more the social instincts. How unselfish is a Dog!”
Dennis Kreb’s Origin of Morality is an excellent attempt to change this situation. It is perhaps the best available overview of evolutionary moral psychology. And in his treatment of the topic, Krebs allows Darwin’s original ideas to stand on a pedestal.
Like Darwin, Krebs wants to show that evolutionary thinking does not discount morality to the realm of mere tactical egoism. He writes:
“There are good reasons to believe that extremely selfish people would fare poorly in most social contexts compared to those who are more altruistically and cooperatively inclined.”
Krebs demonstrates in careful detail why the link between evolution and moral egoism is mistaken. It stems from cherry picking examples or by smuggling the ill-defined term “selfish” between the evolutionary and the psychological domain.
Krebs then turns to explaining the complexity of human morality. Again, he follows Darwin’s basic insight, which sees morality as based on “social instincts”, but developed further by uniquely human tendencies such as conscience, culture, and reasoning.
So why social instincts in the first place? Krebs divides primitive social instincts into “altruistic” and “cooperative” motives. For the evolution of altruism, he suggests a four-legged theory, where kin-selection is supported by sexual selection, group selection and altruistic by-products of imperfect design.
On one level, this is an excellent presentation. All too often, scholars talk as if sympathy for a stranger must be a product of one process alone, whether group selection (Darwin) or misfired kin-selection (Dawkins), or something else. Why choose? As Krebs writes:
“Evolutionary theorists have identified four main ways in which altruism can evolve. This is good news for those who are inclined to look for the best in human nature. Not only may people be altruistic by nature, they may be naturally disposed to emit four types of altruism. “
But if we get technical, there are some flaws in this model. For example, it is not clear why “sexual selection” is labelled as a path to altruism, whereas reputation based “indirect reciprocity” is a path to “cooperation”: both can produce other-regarding behaviours that still increase individual fitness. This worry relates to some general confusion in Krebs’ terminology: it is all but clear when he is talking about evolutionary and when psychological definitions of altruism. This is a typical problem. But given that Krebs explicitly tries to make the division clear, he should be held to higher standards. Yet these remarks are shadows at the edges of a bright field. They do not challenge any of the book’s central arguments.
Krebs’ treatment of cooperation is rather orthodox and uncontroversial. This part features predictable names, like Trivers, Axelrod and Rapaport. But after discussing the evolution of altruism and cooperation, Krebs makes a simple but important suggestion: we have prosocial emotions because they promote either altruism or cooperation or both:
“Altruistic behaviours have been found to stem from empathic, sympathetic, affectionate, reactions evoked when people care for and identify with others. Emotions such as gratitude, pride, guilt, shame, indignation, vindictiveness, and forgiveness uphold systems of cooperative exchange.”
Krebs’ functionalistic account is simple and surprisingly fresh. Philosophers inclined to view moral emotions as only “boos” and “hoorayhs” should take note.
This functionalist account helps make sense of the origin of moral norms, too. The model is simple: In the first place, we learn cultural norms because we are “evolved apprentices” (to use Kim Sterelny’s phrase). But norms come in many shapes. Some promote altruism and cooperation. Some do not. Norms that promote them universally are candidates for universal moral norms (e.g. “don’t rape”, or “don’t lie for selfish reasons”). Norms that can promote altruism and cooperation, but only in a culturally specific context, are candidates for culturally relative moral norms. Norms that do not promote altruism or cooperation at all are – well – not “moral” norms in the first place.
Overall, Krebs has done the field an immense favour with this neat and comprehensive book. There are some odd omissions, though. To me, it is baffling that Krebs does not mention studies by Michael Tomasello on toddler helping behaviour and the emergence of normative language. Nor does he discuss the studies of Yale Infant Cognition lab on babies having a natural disposition to like helpers and dislike hinderers. These are no fringe findings, and the omissions feel bizarre. But to be clear, these findings would only strengthen Krebs’ main argument. This argument is, in short that:
Humans have a set of prosocial emotions. These emotions evolved to help us care for others and cooperate as a team. Humans are also capable of reason, and enculturation, mechanisms that allow the extension of our primitive moral emotions to a fully fledged morality. Humans are not born saints. But as the Chinese sage Mencius suggested over two millennia ago, ethics emerges naturally when we cultivate and extend our inborn “sprouts of virtue”. In this Krebs, Darwin, and Mencius agree.
Notes and links
Darwin discusses human morality mainly in his Descent of Man. For a philosophical introduction to Darwin, see Tim Lewens’ excellent book, titled simply as Darwin.
Darwin was deeply sceptical that sentiments, such as sympathy, could have arisen through the standard process of natural selection. He favored group selection. In The God Delusion, Richard Dawkins has promoted the position that sympathy evolved for relatives, but can misfire in front of a friend or a stranger (see esp. page 220, in 2006 edition).
For Tomasello’s classic studies on helping behaviour and normative language in young children, see his books Natural History of Human Morality, and Becoming Human. For articles, see this, this, and this paper. For a short video clip on helping behaviour in toddlers and chimpanzees, see this video.
For the Yale studies on infant evaluations of prosocial and antisocial behaviour, see this paper. Paul Bloom has a book on the subject called Just Babies: The Origins of good and Evil. He goes through his theories in this webinar. A shorter video is found in this documentary clip.