If an individual adds one more cow to an already full commons, the individual gets the benefit of the extra cow while the cost associated with the extra cow being on the commons is shared by all (e.g. if 5 people share the cost of the commons and the cost of an extra cow is -1 then each will lose -0.2 whereas the individual who adds the cow ends up with +0.8 being +1 for the extra cow -0.2 for his share of the cost of the extra cow). The tragedy is that everyone sees the logic of adding an extra cow and so begins the "solemnity of the remorseless working of things" (Whitehead).
If an individual decides to dump his rubbish rather than pay to have it collected he saves the full amount it would have cost to have the rubbish collected while the cost of the clean up is shared by all.
The Tragedy of the Commons is a 1968 paper by biologist Garrett Hardin. The paper was meant to focus attention on the lack of technical solutions to arrest overpopulation, but its explanation for why commonly-held resources such as groundwater, grazing land, and fisheries are prone to inevitably degrade has influenced the development of environmental and economic policies for resource management.
Garret Hardin's Essay
The Tragedy of the Commons addresses competing viewpoints about how to deal practically with overpopulation. Hardin's explanation of why commonly-held resources degrade was used in the paper as an intellectual exercise to refute the "invisible hand theory" of population control. Hardin wanted to disprove the contention of economist Adam Smith and his disciples that rational decisions made to promote one's self-interest will inevitably be what is best for the common good.
Hardin used cattle grazing on common property as an example of a situation where the cumulative effects of individual decisions result in degradation. Because each cattleman benefits from increasing the size of his herd on the lot, and he feels only a fraction of the negative effects of overgrazing, any rational cattleman would increase the size of his herd. Hence, overgrazing is inevitable, and freedom of the commons in a world that is limited "brings ruin to all."
It should be noted that the theory is relatively simplistic and abstract and it would be difficult to find any resource, be it fisheries or forests, that is completely unregulated in any part of the world. However, the theory depicts what is likely to happen should regulations be ineffective in controlling the behavior of rational individuals who choose to promote their self-interest.
The logic presented in the tragedy of the commons applies to nearly every commonly held property. Below are some common examples.
Air and Water Pollution
Each acting unit, be it a person, company, or factory, receives one hundred percent of the benefits of easy disposal of waste into air or bodies of water but only incurs a fraction of the negative effects of the pollution. When governments do not place limits on an acting unit's pollution releases, the actor benefits economically from free disposal of waste. It is therefore necessary for governments to regulate pollution, providing appealing incentives to prevent pollution or imposing penalties should pollution occur.
The parks are open to everyone without limits on visitation, but the parks themselves are a limited common resource. As the number of visits increases, degradation of the parks becomes more probable. The finite number of parks, coupled with increasing visitation and population growth, makes conservation efforts difficult.
In 1992, the Canadian Government issued a moratorium on cod fishing in the once preeminent cod waters off the coast of Newfoundland. Nearly 40,000 jobs had been lost due to overfishing by a variety of fishing enterprises from many countires (Mason, 2002). The government had placed few restrictions and individual actors had little short-term interest in lowering fish catches. The fishery was devastated and is still under the moratorium. Please see the articles below for details on the collapse.
Unfortunately, mismanagement and overfishing is prevalent in numerous fisheries. Over 90% of the original stock of large predator fish including bluefin tuna, shark, and cod have disappeared (Conservation International). The global fishing fleet is two and a half times greater than what waters can realistically support, with 52% of the world's fisheries fully exploited and 24% overexploited, depleted, or recovering from depletion (WWF).
Forests throughout the world are overexploited and in many countries, especially those lacking resources to make forest protection a priority, the authorities are unable to manage them sustainably.
By making resources private property, owners will have an incentive to keep others off their property, which would limit the number of users, and to use the property sustainably so they can benefit from it in the future. This approach is plausible as long as the property is not too large, which makes it difficult to control trespassing (Feeny, et al, 1990).
Regulating Public Property
Another theoretical solution to avoid degradation of resources is to "keep them as public property, but allocate the right to enter them" (Hardin, 1968). Hardin allows that there are many ways to allocate access - basis of merit, first come first serve, auction system - and while these may not be perfect or even desired, they are necessary to ensure the resources' sustainability.
Holding Property Communally
For smaller resources, such as inshore fisheries, shellfish beds, range lands, and some forests, holding the property communally and allocating use through the community can be feasible (Feeny, et al, 1990). This was not considered by Hardin and communal property is rare around the world. If everyone in a community has an equal right to the resource and the community's population grows, the resource will be brought under increasing strain.
References to the Greek classics
Thucydides (ca. 460 B.C.-ca. 395 B.C.) stated: "[T]hey devote a very small fraction of time to the consideration of any public object, most of it to the prosecution of their own objects. Meanwhile each fancies that no harm will come to his neglect, that it is the business of somebody else to look after this or that for him; and so, by the same notion being entertained by all separately, the common cause imperceptibly decays." (Thucydides (ca. 460 B.C.-ca. 395 B.C.), History of the Peloponnesian War, Book I, Sec. 141; translated by Richard Crawley (London: J. M. Dent & Sons; New York: E. P. Dutton & Co., 1910)) .
Aristotle (384 B.C.-322 B.C.) similarly argued against common goods of the polis of Athens: "That all persons call the same thing mine in the sense in which each does so may be a fine thing, but it is impracticable; or if the words are taken in the other sense, such a unity in no way conduces to harmony. And there is another objection to the proposal. For that which is common to the greatest number has the least care bestowed upon it. Every one thinks chiefly of his own, hardly at all of the common interest; and only when he is himself concerned as an individual. For besides other considerations, everybody is more inclined to neglect the duty which he expects another to fulfill; as in families many attendants are often less useful than a few." (Aristotle (384 B.C.-322 B.C.), Politics, Book II, Chapter III, 1261b; translated by Benjamin Jowett as The Politics of Aristotle: Translated into English with Introduction, Marginal Analysis, Essays, Notes and Indices (Oxford: Clarendon Press, 1885), Vol. 1 of 2.).
* Elliot, Herschel. "A General Statement of Hardin's Tragedy of the Commons".
* Hardin, Garrett. "Tragedy of the Commons". Science 162: 1243-1248.
* Hardin, Garrett. ["Extensions of 'The Tragedy of the Commons'"]. Science 1998.
* The Garrett Hardin Society
* OnTheCommons.org: the Tragedy of the Commons. On the Commons (formerly Tomales Bay Institute) is a network of citizens and organizations exploring new ways to achieve social justice, environmental harmony and democratic participation at all levels of soc
De Young, R. (1999). "Tragedy of the Commons." In D. E. Alexander and R. W. Fairbridge [Eds.], Encyclopedia of Environmental Science. Hingham, MA: Kluwer Academic Publishers.
Feeny, David Fikrit Berkes, Bonnie J. McCay, and James M. Atcheson. "The Tragedy of the Commons: Twenty-Two Years Later." Human Ecology 18, 1990.
Hardin, Garrett. ["Tragedy of the Commons"]. Science 162: 1243-1248.
Hardin, Garrett. Exploring New Ethics for Survival: The Voyage of the Spaceship Beagle, The Viking Press, New York, 1972.
Conservation International. Accessed 1-17-07.
Mason, Fred. ["The Newfoundland Cod Stock Collapse"]. The Electronic Green Journal, 2002.
Myers, Ransom A., Jeffery Hutchings, and Nicholas Barrowman. ["Why do Fish Stocks Collapse? The Example of Cod in the Atlantic]. Ecological Applications 1, p91-106, 1997.
Roy, Noel. "The Atlantic Canada Resource Management Catastrophe: What Went Wrong and What Can We Learn?". The Canadian Journal of Economics 29, pS139-S144, 1996.http://www.panda.org/about_wwf/what_we_do/marine/problems/problems_fishing/index.cfm
WWF. Accessed 1-17-07.
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Tragedy of Freedom in a Commons
The rebuttal to the invisible hand in population control is to be found in a scenario first sketched in a little-known Pamphlet in 1833 by a mathematical amateur named William Forster Lloyd (1794-1852). We may well call it "the tragedy of the commons," using the word "tragedy" as the philosopher Whitehead used it: "The essence of dramatic tragedy is not unhappiness. It resides in the solemnity of the remorseless working of things." He then goes on to say, "This inevitableness of destiny can only be illustrated in terms of human life by incidents which in fact involve unhappiness. For it is only by them that the futility of escape can be made evident in the drama."
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.
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 decisionmaking 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.... But this is the conclusion reached by each and every rational herdsman sharing a commons. Therein is the tragedy. Each man is locked into a system that compels him to increase his herd without limit -- in a world that is limited. Ruin is the destination toward which all men rush, each pursuing his own best interest in a society that believes in the freedom of the commons. Freedom in a commons brings ruin to all.
W. F. Lloyd, Two Lectures on the Checks to Population (Oxford University Press, Oxford, England, 1833).
A. N. Whitehead, Science and the Modern World (Mentor, New York, 1948), p. 17.