Tragedy of the commons

The tragedy of the commons is the idea that when a resource is shared and can benefit the individual at a cost to the community, it is rational for the individual to overuse the resource, even though this collectively leads to the depletion of the resource for everyone. The concept has been widely discussed and criticized in economics, ecology, and other sciences.

The metaphorical term is the title of a 1968 essay by ecologist Garrett Hardin. Versions of this concept extend back to classical antiquity, being discussed by Aristotle. The principal concern of Hardin's essay was overpopulation of the planet. To prevent the inevitable tragedy (he argued) it was necessary to reject the principle (supposedly enshrined in the Universal Declaration of Human Rights) according to which every family has a right to choose the number of its offspring, and to replace it by "mutual coercion, mutually agreed upon".

Some scholars have argued that over-exploitation of the common resource is by no means inevitable, since the individuals concerned may be able to achieve mutual restraint by consensus. Others have contended that the metaphor of a common pasture is inapposite or inaccurate because its exemplar – unfettered access to common land – did not exist historically, the right to exploit common land being controlled by law. The work of Elinor Ostrom, who received the Nobel Prize in Economics, is seen by some economists as having refuted Hardin's claims. Hardin's views on over-population have been criticised as simplistic and racist.