Population and the tragedy of the commons


Jason Collins


May 12, 2011

Like all economists, I am familiar with the concept of the tragedy of the commons. However, possibly like most economists, I had not read Garrett Hardin’s 1968 article from where we derive the phrase - that is, until yesterday. As a result, I did not understand the extent to which overpopulation concerns underpinned Hardin’s writing (HT: Daniel Rankin).

Much of Hardin’s career focussed on overpopulation. He wrote one article called Living on a Lifeboat in which he argued that the lives saved by food aid would only make life worse for later generations (a Malthusian world). He was also an advocate of allowing people to choose their own time to die - he committed suicide with his wife at age 88. Given the debate on fertility at Cato Unbound and the release of Bryan Caplan’s Selfish Reasons to Have More Kids, what Hardin wrote in The Tragedy of the Commons about population is now particularly topical.

Hardin’s concern about overpopulation stemmed from the existence of the commons. For example, in a “dog eat dog” world, if someone had too many children, it would not be a matter of public concern as these parents would leave less descendants than others. This is because they would be unable to adequately care for a large number of children. He wrote:

If each human family were dependent only on its own resources; if the children of improvident parents starved to death; if, thus, overbreeding brought its own “punishment” to the germ line—then there would be no public interest in controlling the breeding of families.

Hardin felt, however, that these conditions did not hold as society was committed to one form of commons, the welfare state. In some ways, this is a direct response to Bryan Caplan’s recent statement that:

As long as parents are financially responsible for their children, any negative effect of population on living standards is internal to the family. ….. [T]he negative externalities, if any, are intra-family.

The question is, thus, to what extent does Caplan’s condition that “as long as parents are financially responsible for their children” hold?

Beyond the welfare state example of Hardin’s, some other negative externalities come to mind. These include the raft of unpriced commons to which people still have access, positional goods, limited land (think beach front real estate) or where desperate conditions result in property rights breaking down (say, Rwanda in 1994 as family plot sizes dropped below that which could sustain a family). The high wages after the Black Death induced population plunge in the 1300s also suggest that externalities extend beyond the family.

When it comes to solving the problem of the tragedy of the commons, Hardin generally favours property rights, although he did consider that the system of private property plus inheritance was unjust. He simply did not see any other alternative.

For the issue of overpopulation and fertility, however, he was less clear. He notes the uselessness of appealing to conscience to cut fertility, as those who continue to breed despite the appeal to conscience will then dominate the population. He considered that we needed to abandon the commons in breeding and relinquish the freedom to breed. On the United Nations Declaration on Human Rights, which allows freedom of choice of family size for the family, Hardin wrote that “If we love the truth we must openly deny the validity of the Universal Declaration of Human Rights”.

How precisely Hardin proposed to curtail the right to breed, however, is not addressed in his tragedy of the commons article. I understand that he addressed specific population control measures in more detail in his later work, which might be the subject of a later post.