The Better Angels of Our Nature: Why Vio - By Steven Pinker Page 0,324

nice guy (or gal) get shocked. When the double-crosser got shocked, the women could not turn off their empathy: their insula still lit up in sympathy. But the men hardened their hearts: their own insula stayed dark, while their striatum and orbital cortex lit up, a sign of a goal sought and consummated. Indeed, those circuits lit up in proportion to the men’s stated desire for revenge. The results are in line with the claim by difference feminists such as Carol Gilligan that men are more inclined toward retributive justice and women more toward mercy.178 The authors of the study, though, caution that the women may have recoiled from the physical nature of the punishment and might have been just as retributive if it had taken the form of a fine, criticism, or ostracism.179

There is no gainsaying the cool, sweet pleasure of revenge. A villain getting his comeuppance is a recurring archetype in fiction, and it’s not just Dirty Harry Callahan whose day is made when a bad guy is brought to violent justice. One of my most enjoyable moments as a moviegoer was a scene in Peter Weir’s award- winning Witness. Harrison Ford plays an undercover detective who is assigned to live with an Amish family in rural Pennsylvania. One day, in full Amish drag, he accompanies them to town in their horse-drawn buggy, and they are stopped and harassed by some rural punks. True to their pacifism, the family turns the other cheek, even as one of the punks taunts and bullies their dignified father. The straw-hatted Ford does a slow burn, turns toward the punk, and to the astonishment of the gang and the delight of the arthouse audience, coldcocks him a good one.

What is this madness called revenge? Though our psychotherapeutic culture portrays vengeance as a disease and forgiveness as the cure, the drive for revenge has a thoroughly intelligible function: deterrence.180 As Daly and Wilson explain, “Effective deterrence is a matter of convincing our rivals that any attempt to advance their interests at our expense will lead to such severe penalties that the competitive gambit will end up a net loss which should never have been undertaken.”181 The necessity of vengeful punishment as a deterrent is not a just-so story but has been demonstrated repeatedly in mathematical and computer models of the evolution of cooperation.182

Some forms of cooperation are easy to explain: two people are related, or married, or are teammates or bosom buddies with the same interests, so what is good for one is good for the other, and a kind of symbiotic cooperation comes naturally. Harder to explain is cooperation when people’s interests at least partly diverge, and each may be tempted to exploit the other’s willingness to cooperate. The simplest way to model this quandary is a positive-sum game called the Prisoner’s Dilemma. Imagine a Law and Order episode in which two partners in crime are held in separate jail cells and the evidence against them is marginal, so each is offered a deal by the assistant district attorney. If he testifies against his partner (“defects” against him) while the partner stays true (“cooperates”—with the partner, that is), he will go free while his partner is sent away for ten years. If each of them defects and testifies against the other, they will both go to jail, but their sentences will be reduced to six years. If each stays loyal to the other, the prosecutor can only convict them of a lesser crime, and they will be free in six months. Figure 8–5 shows the payoff matrix for their dilemma; the choices and payoffs for the first prisoner (Lefty) are printed in black; those for his partner (Brutus) are printed in gray.

FIGURE 8–5. The Prisoner’s Dilemma

Their tragedy is that both ought to cooperate and settle for the reward of a six-month sentence, which gives the game its positive sum. But each will defect, figuring that he’s better off either way: if the partner cooperates, he goes free; if the partner defects, he only gets six years rather than the ten he would get if he had cooperated. So he defects, and his partner, following the same reasoning, also defects, and they end up serving six years rather than the six months that they could have served if they had only acted altruistically rather than selfishly.

The Prisoner’s Dilemma has been called one of the great ideas of the 20th century, because it distills the tragedy of social life into such a succinct formula.183