From the July/August 2009 issue of The National Interest.
HOW DOES one escape a dilemma in which multiple individuals acting in their own rational self-interest can ultimately destroy a shared limited resource-even when it is clear this serves no one in the long run?
In 1968, Science published Garrett Hardin's landmark article "The Tragedy of the Commons." Hardin relied on the metaphor of a small English village in the eighteenth century. Each family has a house with a small plot of land for growing vegetables. In addition, there is a large, common area used by all the villagers to graze their livestock. Each villager has a cow or two that provide the family with its milk. The common area is large enough to support the entire village. Then the village begins to grow. Families get larger, and procure an extra cow. New families move in. Suddenly, the common is threatened; it is being overgrazed. Grass is consumed so fast that there is not enough time for it to replenish itself before rains erode the topsoil. Each cow no longer has quite enough to eat, and thus yields less milk than it did before. If the overuse of the common continues, there will be a slow but sure decrease in the number of animals it can support until, finally, it becomes useless for grazing.
