Garret Hardin’s population dilemma

December 23, 2014


Who trusted God was love indeed
And love Creation’s final law
Tho’ Nature, red in tooth and claw
With ravine, shriek’d against his creed
~from “In Memoriam A. H. H.”
Alfred Lord Tennyson, 1850

Garret Hardin (1915-2003) was an ecologist interested in overpopulation, and a biology professor at the University of California at Santa Barbara.

He is known for saying about human participation in ecology, “You cannot do only one thing,” meaning unintended consequences are inevitable.

He published “The Tragedy of the Commons,” in Science in 1968. (The essay is now widely available online.) It considers how to manage human population, and, to a certain extent, uses population to stand for pollution, over-fishing, and the variety of ways in which human exploitation of shared resources endangers the resource.

The central metaphor is a field in which all the local farmers pasture their livestock. If the common herd exceeds the field’s capacity, the animals will erode the soil, and indigestible weeds will replace grass.

To preserve the commons, the herd should be limited to what the field can maintain and remain healthy. That number should be divided by the number of farmers to determine how many animals each farmer may raise.

It makes sense for an individual farmer to exceed his proper fraction. A farmer gets the entire benefit of each extra animal, but experiences only a fraction of the “cost”—damage to the field. The tragedy of the commons is that cheating seems sensible.


Hardin gives several modern examples, including a city with a parking problem that granted free holiday parking, ranchers lobbying the Bureau of Land Management to allow overgrazing on rented range, and overpopulation.

Just as early farmers could crash a common pasture, Hardin says we can crash the larger commons—Planet Earth—one baby at a time. Population growth must eventually become zero. Otherwise, human pollution and resource use will overwhelm our environment’s ability to process waste and produce the resources on which we depend.

Hardin argues that renewables, nuclear power, and modern grains will not prevent the damage of an ever-growing human population. Solving the problem requires changes in “human values or ideas of morality,” and “more than one generation of hard analytical work—and much persuasion.”

“We can make little progress in working toward optimum population size until we explicitly exorcise the spirit of Adam Smith in the field of practical demography.” Smith believed individuals acting in their own self-interest would make the best decisions for the entire society, a notion contradicted by the scenario of the common pasture.

Hardin explicitly meant to limit reproduction by coercion. He objected even to the use of the word “responsible” in relation to propagation. He felt that an appeal to conscience without a “substantial quid pro quo” was an attempt to get something for nothing.

Further, without laws limiting childbearing, the responsible family would find itself surrounded by those who had acted irresponsibly and, “conscience is self-eliminating.” Those irresponsible families would have irresponsible children, who would do it again, eventually outbreeding the responsible.

Hardin’s solution was “mutual coercion mutually agreed upon.” A bank robber, for example, is treating the bank as if it were a commons. Society doesn’t politely ask bank robbers to behave responsibly; we punish people who rob banks.

Hardin is pretty “red of tooth and claw.” He said genocide could be useful in curbing population; food aid to starving countries contributes to overpopulation; and he co-signed a Wall Street Journal editorial supporting Charles Murray’s The Bell Curve, a book that claimed whites are smarter than blacks. Aged and infirm, Hardin and his wife committed suicide together.

Hardin suggested privatizing the commons as one way of protecting them, but admitted that it isn’t possible to put fences around the sky. Leftists and historians have objected to this suggestion, but Hardin’s discussion of private property is in two brief passages in an essay of almost 5,000 words. His comments about privatization are asides, with a progressive tax on offspring being his preferred method of limiting population. That we should face the population problem was his thesis.

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