Friday, December 12, 2003

dismal "science"
New Science special issue on the "tragedy of the commons," (featuring among others Rosegrant and Cline, Global Food Security). Also "web resources" (which may or may not be freely accessible), including Garrett Hardin's original paper from 1968. The love of scientists for this peer-reviewed statement of the obvious has always seemed bizarre. (His juxtaposition with contemporary papers in the same journal suggests one explanation, Hardin's now-startling ability to write clearly and well). Famously,
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.*
"No shit," the less charitable reader might be tempted to respond.

This paper and its meme are inexplicably popular among those who happily, and incessantly, proclaim the wrongness of Thomas Malthus. But the "tragedy of the commons" is obvious precisely because it is Malthusian, and explicitly:

Population, as Malthus said, naturally tends to grow "geometrically," or, as we would now say, exponentially. In a finite world this means that the per capita share of the world's goods must steadily decrease. Is ours a finite world?

A fair defense can be put forward for the view that the world is infinite; or that we do not know that it is not. But, in terms of the practical problems that we must face in the next few generations with the foreseeable technology, it is clear that we will greatly increase human misery if we do not, during the immediate future, assume that the world available to the terrestrial human population is finite.

Of course, the hatred of Malthus comes from this:
If I allow that by the best possible policy, by breaking up more land and by great encouragements to agriculture, the produce of this Island may be doubled in the first twenty-five years, I think it will be allowing as much as any person can well demand.

In the next twenty-five years, it is impossible to suppose that the produce could be quadrupled. It would be contrary to all our knowledge of the qualities of land. The very utmost that we can conceive, is, that the increase in the second twenty-five years might equal the present produce. Let us then take this for our rule, though certainly far beyond the truth, and allow that, by great exertion, the whole produce of the Island might be increased every twenty-five years, by a quantity of subsistence equal to what it at present produces. The most enthusiastic speculator cannot suppose a greater increase than this. In a few centuries it would make every acre of land in the Island like a garden.

Yet this ratio of increase is evidently arithmetical.

His crime was skepticism of the perfectibility of man. He replaced blind faith in scientific progress with a careful (and then obvious) analysis of the history of agronomy, and so failed to predict the industrial scale fixation of atmospheric nitrogen, dwarf cereal hybrids, and a food supply that did therefore manage to increase at a greater than arithmetical rate. What a moron.

For these people, Malthus is totem like the luddites: people who stupidly opposed "progress". The astonishing thing is the complete logical breakdown of this totemic analysis (or lack thereof): the casual mockery of luddism is based on a refusal to acknowledge that their resistance was an attempt to preserve their own livelihoods -- an act of "rational self-interest"; that of Malthus on the inability to see that he simply articulated a problem of science -- in essence, the tragedy of the commons. Duh.

*In case the unfolding tragedy seems not so obvious, I append its conclusion:

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.

Probably his willingness to spell out the obvious at such length (and with numbers!) also explains why scientists love this guy so much more than Malthus.


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