Why Revenge Makes Sense


This is probably useful for office politics and dealing with bullies.

Does revenge pay in the real world? Does the credible threat of punishment induce fear in the heart of potential exploiters and deter them from exploiting? The answer from the lab is yes….

  • the ability of an investor to punish a faithless trustee puts enough fear into the trustee to return a fair share of the appreciated investment.
  • When people are given the opportunity to punish free riders, people don’t free-ride.
  • Revenge can work as a deterrent only if the avenger has a reputation for being willing to avenge and a willingness to carry it out even when it is costly.

That helps explain why the urge for revenge can be so implacable, consuming, and sometimes self-defeating (as with pursuers of self-help justice who slay an unfaithful spouse or an insulting stranger).

Moreover, it is most effective when the target knows that the punishment came from the avenger so he can recalibrate his behavior toward the avenger in the future.  That explains why an avenger’s thirst is consummated only when the target knows he has been singled out for the punishment.  These impulses implement what judicial theorists call specific deterrence: a punishment is targeted at a wrongdoer to prevent him from repeating a crime.  The psychological equivalent of general deterrence is the cultivation of a reputation for being the kind of person who cannot be pushed around.

The effectiveness of revenge as a deterrent can explain actions that are otherwise puzzling. The rational actor theory, popular in economics and political science, has long been embarrassed by people’s behavior in yet another game, the Ultimatum game.  One participant, the proposer, gets a sum of money to divide between himself and another participant, the acceptor, who can take it or leave it. If he leaves it, neither side gets anything.

The first feature behind Tit for Tat’s success is that it is nice: it cooperates on the first move, thereby tapping opportunities for mutually beneficial cooperation, and it does not defect unless defected upon.

The second is that it is clear: if a strategy’s rules of engagement are so complicated that the other players cannot discern how it is reacting to what they do, then its moves are effectively arbitrary, and if they are arbitrary, the best response is the strategy Always Defect.  Tit for Tat is easy for other strategies to cotton on to, and they can adjust their choices in response.

Third, Tit for Tat is retaliatory: it responds to defection with defection, the simplest form of revenge.  And it is forgiving: it leaves the gates of repentance open, so if its adversary switches to cooperation after a history of defection, Tit for Tat immediately cooperates in return.

The last feature, forgivingness, turns out to be more important than everyone first appreciated. A weakness of Tit for Tat is that it is vulnerable to error and misunderstanding. Suppose one of the players intends to cooperate but defects by mistake. Or suppose it misperceives another player’s cooperation as defection, and defects in retaliation. Then its opponent will defect in retaliation, which forces it to retaliate in turn, and so on, dooming the players to an endless cycle of defection—the software equivalent of a feud. In a noisy world in which misunderstanding and error are possible, Tit for Tat is bested by an even more forgiving strategy called Generous Tit for Tat

Every once in a while Generous Tit for Tat will randomly grant forgiveness to a defector and resume cooperating. The act of unconditional forgiveness can flick a duo that has been trapped in a cycle of mutual defection back onto the path of cooperation. A problem for overly forgiving strategies, though, is that they can be undone if the population contains a few psychopaths who play Always Defect and a few suckers who play Always Cooperate. The psychopaths proliferate by preying on the suckers, and then become numerous enough to exploit everyone else.

One successful contender in such a world is Contrite Tit for Tat, which is more discriminating in its forgiveness. It remembers its own behavior, and if a round of mutual defection had been its fault because of a random error or misunderstanding,

  • it allows its opponent one free defection and then switches to cooperation.
  • But if the defection had been triggered by its opponent, it shows no mercy and retaliates.

If the opponent is a Contrite Tit for Tatter as well, then it will excuse the justified retaliation, and the pair will settle back into cooperation. So not just vengeance, but also forgiveness and contrition, are necessary for social organisms to reap the benefits of cooperation.

A rational proposer would keep the lion’s share; a rational respondent would accept the remaining crumbs, no matter how small, because part of a loaf is better than none. In actual experiments the proposer tends to offer almost half of the jackpot, and the respondent doesn’t settle for much less than half, even though turning down a smaller share is an act of spite that punishes both participants. Why do actors in these experiments behave so irrationally? The rational actor theory had neglected the psychology of revenge. When a proposal is too stingy, the respondent gets angry—indeed, the neuroimaging study I mentioned earlier, in which the insula lit up in anger, used the Ultimatum game to elicit it.  The anger impels the respondent to punish the proposer in revenge. Most proposers anticipate the anger, so they make an offer that is just generous enough to be accepted. When they don’t have to worry about revenge, because the rules of the game are changed and the acceptor has to accept the split no matter what (a variation called the Dictator game), the offer is stingier.

Pinker, Steven (2011-10-04). The Better Angels of Our Nature: Why Violence Has Declined (Kindle Locations 11844-11868). Penguin Group. Kindle Edition.


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