Sunday, January 4, 2009

Key Concept - Tragedy of the Commons

I am beginning a semi-recurring series of interesting (to me) topics to further explore and consolidate certain "Key Concepts". Up first is the namesake of this blog: "The Tragedy of the Commons".

The term and concept was first officially coined by Garrett Hardin in a 1968 Science magazine article, which I highly recommend. (article here) It describes the inclination for multiple rational individuals to act in their own self-interest in the short-term, even at the detriment of all over the long-term.

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.
The article raises some very interesting and sometimes rather controversial ideas, the most outstanding being the call to relinquish the freedom to procreate. I'd prefer to highlight some of the other, perhaps less extreme, points:

- There are problems that do not have technical solutions
- It is not mathematically possible to maximize for two (or more) variables at the same time
- Optimal human population is below the maximum population
- The morality of an act is a function of the state of the system at the time it is performed
- An alternative to the commons need not be perfect just to be preferable

While the article is mainly concerned with population growth, the author does mention pollution as an example. In current events, Global Warming certainly fits squarely in the category of a 'Tragedy of the Commons'. The author places global population in the "no technical solution" category; unfortunately, I am more and more inclined to do the same for climate change. Certain parallels are quite striking: as the author cautions against the appeal to conscience, most anti-global warming appeals are decidedly guilt-based. The article posits that these calls are not productive in the long- or short-term.

The long-term disadvantage of an appeal to conscience should be enough to condemn it; but has serious short-term disadvantages as well. If we ask a man who is exploiting a commons to desist "in the name of conscience," what are we saying to him? What does he hear?--not only at the moment but also in the wee small hours of the night when, half asleep, he remembers not merely the words we used but also the nonverbal communication cues we gave him unawares? Sooner or later, consciously or subconsciously, he senses that he has received two communications, and that they are contradictory: (i) (intended communication) "If you don't do as we ask, we will openly condemn you for not acting like a responsible citizen"; (ii) (the unintended communication) "If you do behave as we ask, we will secretly condemn you for a simpleton who can be shamed into standing aside while the rest of us exploit the commons."
My fear is that a solution that is effective, equitable, and enforceable is simply beyond the global community's technical and political ability. This is the true tragedy - "the solemnity of the remorseless working of things".


Anonymous said...

I look forward to more on this theme. Here are some related links you may find interesting...

Approaching the Limits

Bruce Sundquist on environmental impact of overpopulation

The Oil Drum Peak Oil Overview - June 2007

Bandura etc.

Albert Bartlett on the exponential function as it relates to population and oil:

...and of course the classic "Overshoot" by Catton

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