An Evolutionary Approach to Norms

Summary of: An Evolutionary Approach to Norms

Author(s) / Editor(s)

Exploration of games in which punishment is possible and cheating is not automatically detected reveals that norms can emerge and stabilize only if those who fail to punish violators are also punished.

Publication Reference

Published in/by
American Political Science Review 80, No. 41095-1111


  • Norms can emerge in competitive situations when players can observe each other and imitate the strategies of successful players.
  • N-person Prisoner's Dilemma games can't be resolved with simple reciprocity without enabling cooperators to also punish defectors.
  • Norms can emerge and grow stable if metanorms establish a willingness to not only punish violators but also those who fail to punish violators.
  • Norms likely emerge from behaviors that signal others to reward individuals (reputation), and spread through both imitation as well as punishment of violators.
  • "There may be some useful cooperative norms that could be hurried along with relatively modest interventions."

The decrease in punishment of those who failed to punish violators may have played a part in the sudden collapse of communism, and Granovetter noted that riots can have tipping points in which "a slight change in the willingness of a few people to act first can get the ball rolling." Axelrod defines norms thus: "A norm exists in a given social setting to the extent that individuals usually act in a certain way and are often punished when seen not to be acting in this way." Therefore, norms are a matter of degree, not all or nothing. "By linking vengefulness against nonpunishers with vengefulness against defectors, the metanorm provides a mechanism by which the norm against defection becomes self-policing." Reputation plays a role because defection is not only a means for a defector to harvest a payoff, but a signal that can be used be others: "a norm is likely to originate in a type of behavior that signals things about individuals that will lead others to reward them." The observation from norms-game trials that norms can sometimes establish themselves quickly led Axelrod to conclude that "there may be some useful cooperative norms that could be hurried along with relatively modest interventions."