Social Dilemma

A social dilemma is formally defined as an incentive structure in which a deficient outcome is collectively achieved when each individual (in a group of two or more people) makes choices in accordance with a dominating strategy. A strategy is dominating if the personal consequences of behaving according to it are superior to the consequences of behaving according to all other strategies, regardless of the behavior of others in the group. The outcome is considered to be “deficient” when that outcome is preferred less than other outcomes by all members of the group. The commons dilemma, a social trap, the public goods problem, and the free-riding problem are all used to refer to a social dilemma. Real-world examples of social dilemmas range from an arms race between superpowers, the overharvesting of regenerating natural resources, protective trade policies, traffic jams, the use of modern amenities that create global warming, and so on. In these examples, the choice that follows the dominating strategy—often called the choice of “defection,” or “free-riding” in some contexts—is the one that brings forth the most desirable outcome for the individual. Using the example of the arms race, the individual consequence for choosing to increase military power is military advantage. Using the example of overharvesting resources, the individual consequence for choosing to overharvest is the immediate profit reaped from ooverharvesting. However, if each person follows the dominating strategy and makes the choice of defection, the collective outcome is less desirable an outcome than if the individuals had followed another strategy and made an alternative, cooperative choice. For example, everyone benefits more if both superpowers disarm than if both expand their military power. Furthermore, everyone benefits more if the fishermen refrain from overharvesting than if they overharvest, and so on.

The current use of the term social dilemma summarized above is relatively new. However, the study of social dilemmas began much earlier, in the 1950s. Robyn Dawes used the term when he reviewed experimental work that had previously been described as “n-person prisoner's dilemmas.” Social dilemmas were originally conceptualized as a group version (or n-person version) of the prisoner's dilemma, which usually involves only two people. The [Page 732]name “prisoner's dilemma” (PD) comes from a story of two individuals suspected of a crime. Two suspects who have been arrested for a serious crime are being interrogated by a district attorney. The district attorney does not have enough evidence to convict either of the suspects of the crime. Therefore, the district attorney needs a confession from at least one of the suspects. He offers a deal to each “prisoner” independently. If one of the prisoners confesses and the other prisoner does not confess, the one who confesses gets acquitted and the one who does not confess gets the maximum penalty. If both prisoners confess, both are charged with the serious crime but both will receive a lenient penalty. If neither prisoner confesses, each prisoner is charged with a minor offense (not the serious crime) and receives a minor penalty. Both prisoners face a choice between confessing and not confessing. The dominating strategy is confessing, since individually, each prisoner is better off by confessing than by not confessing no matter what the other does. For example, Prisoner A is better off when he confesses (lenient penalty for the serious crime) than when he does not confess (the maximum penalty for the serious crime), if Prisoner B confesses. If Prisoner B does not confess, A is again better off by confessing (no penalty) than by not confessing (penalty for a minor crime). However, when each takes this dominating choice of confessing, each receives a lenient penalty for the serious crime, whereas each prisoner could have avoided that penalty by not confessing.

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