THE DYNAMICS OF SOCIAL DILEMMAS

76 SCIENTIFIC AMERlCAN March 1994 I magine that you and a group of friends are dining at a fine restaurant \vith an unspoken agreement to dh1de the check evenly. What do you order? Do you choose the modest chicken entree or the pricey lamb chops? The house wine or the (abemet Sauvignon 1983? If you are extravagant, you could enjoy a superlative dinner at a bargain price. But if everyone in the parry reasons as you do, the group will end up with a hefry bill to pay. And why should others settle for pasta pri· mavera when someone is having grilled pheasant at their expense? This lighthearted situation, which we call the Unscrupulous Diner's Dilemma, typifies a class of serious, difficult problems that pervade sociery. Sociologists, economists and political scientists find that this class of social dilemma is central to a wide range of issues, such as protecting the environment, conserving natural resources, eliciting donations to chariry, slowing military arms races and containing the population e>..'Plosion. All these issues involve