Sunday, November 20, 2005

The Tragedy of the Commons

Those of us involved in civic entrepreneurship appreciate how difficult it is to create a common area where everyone can benefit. One the one hand, few want to pay for the commons, while on the other hand everyone wants to benefits from it.

In the December 13, 1968 issue of Science, Garrett Hardin writes a very insightful article, The Tragedy of the Commons. He includes this analogy to describe the tragedy.

The tragedy of the commons develops in this way. Picture a pasture open to all. It is to be expected that each herdsman will try to keep as many cattle as possible on the commons. Such an arrangement may work reasonably satisfactorily for centuries because tribal wars, poaching, and disease keep the numbers of both man and beast well below the carrying capacity of the land. Finally, however, comes the day of reckoning, that is, the day when the long-desired goal of social stability becomes a reality. At this point, the inherent logic of the commons remorselessly generates tragedy.

As a rational being, each herdsman seeks to maximize his gain. Explicitly or implicitly, more or less consciously, he asks, "What is the utility to me of adding one more animal to my herd?" This utility has one negative and one positive component.

1) The positive component is a function of the increment of one animal. Since the herdsman receives all the proceeds from the sale of the additional animal, the positive utility is nearly +1.

2) The negative component is a function of the additional overgrazing created by one more animal. Since, however, the effects of overgrazing are shared by all the herdsmen, the negative utility for any particular decision-making herdsman is only a fraction of -1.

Adding together the component partial utilities, the rational herdsman concludes that the only sensible course for him to pursue is to add another animal to his herd. And another; and another. . . . But this is the conclusion reached by each and every rational herdsman sharing a commons. Therein is the tragedy. Each man is locked into a system that compels him to increase his herd without limit--in a world that is limited. Ruin is the destination toward which all men rush, each pursuing his own best interest in a society that believes in the freedom of the commons. Freedom in a commons brings ruin to all.

Click for the full text of The Tragedy of the Commons

1 comment:

Chris Klasing said...


Very insightful post. The tragedy of the commons has often been used to describe environmental issues in which the common resource is clean water or clean air. Here in the Upstate the common resource might be our quality of life; more specifically our ability to get around or enjoy a naturally wooded area.

One more Lowe's or Wal Mart on Woodruff Road or Fairview Avenue may be only an incremental investment for the developer, the builder, the store, and others who gain from the addition. But for the rest of us we become increasingly subject to Atlanta-like gridlock, and have to live surrounded by more concrete and less green space.

What's the answer? Probably not a simple one, but we likely do need to move in the direction of more planning and less freedom to sell real estate for whatever purpose we choose and build whatever and wherever we choose.