Ethical Conundrums: Moral Tribes: Emotion, Reason, and the Gap between Us and Them
by Joshua Greene
Penguin Press: 2013

We begin on a serene pasture inhabited by a tribe of shepherds. Motivated by personal wealth, one by one the herders begin adding more sheep to their individual flocks. Soon enough the once lush meadow is overrun, and ultimately the sheep destroy it. Such is the tragedy of the commons, the idea that people acting out of self-interest will deplete shared resources to the detriment of the group.

In his new book, Harvard University psychologist Greene uses the concept of the tragedy of the commons to explain moral behavior. He argues that our moral brain evolved to promote cooperation within groups, not between them. Groups will differ in their views, causing conflict. We see this clash of morals play out today among different racial groups, religious factions and warring nations.

To better understand how moral conflicts arise, Greene turns to neuroscience. Based on his functional MRI studies, he proposes that our moral brain operates like a dual-mode camera: it has an automatic setting, for emotional instincts, and a manual setting, for logical reasoning (a concept first popularized by psychologist Daniel Kahneman). When dealing with moral dilemmas, we instinctively react emotionally, but if we step back from the situation, logical reasoning can override a gut reaction.

To illustrate the moral brain at work, Greene describes the famous trolley problem, in which a bystander must choose whether to send a man to his death to save five men. If we identify with the solo man, we are more likely to react emotionally (automatic setting) and want to save him, but if we can think logically about the greater good (manual setting), we often choose to save five lives at the expense of one. Greene explores thorny issues, such as physician-assisted suicide, abortion and capital punishment, through the lens of moral tribalism.

Moral Tribes weaves together age-old philosophical musings, theoretical and real-world problems, and recent brain research, but Greene is at his best when describing his personal journey investigating the mysteries of the moral brain. In his ambition to cover so much territory, however, he goes on too many tangents and at times loses the reader in minutiae.

Greene's main objective here is to begin developing a unified system of morality that promotes cooperation among all groups. Although he does not accomplish this lofty goal, he nonetheless furthers our understanding of the moral brain. Looking out for the best interest of the global community, he believes, will move us closer to a morally united world.