A metaphor at midlife: 'The Tragedy of the Commons' turns 40.

Since 1968, when Garrett Hardin wrote his essay entitled 'The Tragedy of the Commons', the idea that human reproduction must be brought under the coercive control of state power has been rejected by every government on earth, with the qualified exception of the People's Republic of China. The metaphor that Hardin used to convey his message, however, has proliferated, adapted and evolved. Its original neo-Malthusian message now largely forgotten, 'The Tragedy of the Commons' has become a wildly popular metaphor in a variety of fields from ecology to property law to the programmatic architecture of the Internet.