Thinking and Deciding

Chapter 18
Social dilemmas: Cooperation
versus defection
The best chance for gains comes through cooperation.
Fortune cookie message
This chapter focuses on a specific type of decision problem: decisions involving
situations in which the narrow self-interest of each person in a group conflicts with
the interest of the group as a whole. Retired people who have medical insurance that
covers all expenses stand to gain (from extra medical attention and reassurance) if
they visit their doctor weekly, sick or not, but if everyone in their group did this,
their insurance premiums would skyrocket. People who watch viewer-supported
television can save their money by not contributing to support the station they watch,
but if everyone did this the station would be off the air, and all who like to watch
it would suffer. Each farmer stands to gain from letting the family cows graze on
the commons, the common pasture for the town, but if everyone did this the pasture
would disappear (Hardin, 1968).
Such situations are called social dilemmas, orcommons dilemmas (by analogy
with the common-pasture example). 1 In a simple social dilemma, each person is
better off doing one sort of thing (given what others do), but all are better off if all do
something else. The action that is best for all is called cooperation; the action best
for the self is called defection. 2 It is best for all (cooperative) not to overgraze the
common pasture but best for each to do so.
1 Other terms used for the same idea, or variants of it, are: public goods problem; prisoner’s dilemma;
externalities; and free-rider problem.
2 The basic theory of cooperation and defection comes from the mathematical theory of games, which
was developed largely by the mathematician John von Neumann as early as the 1920s. This theory first
attracted the attention of social scientists and philosophers in the early 1950s, after the publication of von
Neumann and Morgenstern’s Theory of Game and Economic Behavior (1947), the same book that called
attention to utility theory.
441