Review of Moral Tribes

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  • Innovative
  • Scientific
  • Engaging


“Us” versus “Them” dynamics have occupied a central place in human society since time immemorial. In this intriguing book, psychologist Joshua Greene explores the resource-based reasons why people tend to fight those outside their “tribe” – such as the desire for decent places to live, good food, healthy bodies and enough time to enjoy the people they care about – as well as the more ephemeral causes of conflict. According to Greene, tribes often fight each other because they have different conceptions of what it means to live in a good and just community. Such clashes have only grown as life has become more globalized, Greene notes. Still, there is hope if people can find ways to speak across their differences.

Greene delves into a number of subject areas in the course of his examination of the causes of and cures for moral conflicts – including neurology, psychology, social science and philosophy – and does not shy away from academic terminology. Not all readers will find Greene’s claims about the possibilities inherent in his version of utilitarianism, which he calls “deep pragmatism,” entirely convincing; nevertheless, the text is rarely dry or boring. Moreover, the author’s original research, engaging examples and practical suggestions will interest anyone bewildered by the strident ethical conflicts so prevalent in today’s world.

About the Author

Joshua Greene is an experimental psychologist, neuroscientist, philosopher and Professor of Psychology at Harvard University.


The “Tragedy of the Commons” illustrates a core problem in getting people to cooperate.

Joshua Greene begins his exploration of the problem of moral conflict with a hypothetical situation: Suppose you are one of a group of people raising livestock on relatively limited common land. When an animal is sold at auction, its owner receives the profits, even though everyone contributed, via the common land, to the expense of raising it. Given this arrangement, each individual has an incentive to continue adding animals to his or her herd. But if every individual in the group behaves in accordance with that self-interest, the grazing land they all hold in common will soon be destroyed. The conflict between self-interest and collective interest, which ecologist Garrett Hardin termed the “Tragedy of the Commons,” is sometimes, but not always, a part of group dynamics, Greene writes. Indeed, it only rears its head when the interests of the individual are out of sync with those of the group; and even then, they are not mutually exclusive. 

Ethics evolved in order to make cooperation possible.

In the wake of Darwin’s theory of natural selection, the question arose: How did ethics or morality among humans evolve? “Survival of the fittest” would, after all, seem to reward pure egotism rather than cooperation and compromise. Nonetheless, Greene states, people often decide to allow the interests of the group to rule. Humans evolved to facilitate this kind of cooperation, but only with certain categories of people: those who are part of their “tribe” or with whom they have a personal relationship. This is because of the competitive nature of evolutionary biology: Cooperation between groups must be limited, and cooperation with members of your own group must offer an advantage – less of a chance, for example, of going hungry. Morality is, therefore, an adaptive tool of both cooperation and competition. 

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