Tragedy of the Commons

A “tragedy of the commons” occurs because people take something out of or put something into a resource because each individual who has a right to the resource perceives that the benefits derived from doing so outweigh associated costs. In the familiar example, a commons may be a field on which sheep can graze, and all those in a village may use such a field to feed their sheep. The “tragedy” occurs because rights to use the resource are widely assigned or collectively owned, with no one person having the right to exclude the others. Each person or entity that has a right to use the resource does so without regard to the actions of others or the value of the resource, and eventually the resource is wasted or depleted. In the above example, the result is overgrazing of the commons. Each villager who owns sheep will seek to maximize the benefit he or she derives by using the resource. Other examples are familiar as well. They include the use of aquifers, hunting territories, and fishing grounds.

The cause or logic of the tragedy is easily described. Each person with ownership rights derives some benefit from using the commons. For instance, in thinking about adding another sheep to his herd, our villager will consider how this benefit is affected by the costs. But the costs of adding one more sheep are spread across all villagers using the commons, so the costs accruing to the individual villager will only be a fraction of the real costs of increasing the herd. Thus, the individual villager perceives that the benefit he derives is increased by more than the costs of adding one more sheep to his herd. Since we assume that our villager will act rationally, he will add another sheep to his herd. And since all villagers who have herds will perceive the same low costs, additional [Page 2094]sheep will be added to the herd of each villager, and overgrazing of the commons will be the result.

In this case, the tragedy is occurring because people are taking something away from the commons. But a tragedy of the commons can also occur by dumping or putting something into the commons as opposed to taking something out of it. Again, examples are familiar. They include pollution of the air, land, oceans, and waterways. In each case, something is dumped or put into the commons.

Garrett Hardin, in a remarkable essay published in 1968, argued that “technical solutions” when applied to a subset of problems such as population growth and the environment will not work. He defined a technical solution as one that required a change in the techniques of the natural sciences, which demanded little or no change in human values or ideas of morality. For instance, in the above example, a technical solution may be the fertilization of the field. Since no technical solution is available in this subset of problems, a solution might be found in an appeal to the morality of resource users. But Hardin argued that appealing to the conscience of resource users will not work because self-interest will trump other considerations and that a solution can only be found coercively.

...