The tragedy of the commons is a dilemma arising from the situation in which multiple individuals, acting independently and rationally consulting their own self-interest, will ultimately deplete a shared limited resource, even when it is clear that it is not in anyone's long-term interest for this to happen. This dilemma was described in an influential article titled "The Tragedy of the Commons", written by ecologist Garrett Hardin and first published in the journal Science in 1968.[1]
Hardin's Commons Theory is frequently cited to support the notion of sustainable development, meshing economic growth and environmental protection, and has had an effect on numerous current issues, including the debate over global warming. An asserted impending "tragedy of the commons" is frequently warned of as a consequence for adopting policies which restrict private property and espouse expansion of public property.[2][3]
Central to Hardin's article is an example (first sketched in an 1833 pamphlet by William Forster Lloyd) involving medieval land tenure in Europe, of herders sharing a common parcel of land, on which they are each entitled to let their cows graze. In Hardin's example, it is in each herder's interest to put the next (and succeeding) cows he acquires onto the land, even if the quality of the common is damaged for all as a result, through overgrazing. The herder receives all of the benefits from an additional cow, while the damage to the common is shared by the entire group. If all herders make this individually rational economic decision, the common will be depleted or even destroyed, to the detriment of all. Hardin also cites modern examples, including the overfishing of the world's oceans and ranchers who graze their cattle on government lands in the American West.[1]
A similar dilemma of the commons had been discussed by agrarian reformers since the 18th century.[4] Hardin's predecessors used the alleged tragedy, as well as a variety of examples from the Greek Classics, to justify the enclosure movement. German historian Joachim Radkau sees Garrett Hardin's writings as having a different aim in that Hardin asks for a strict management of common goods via increased government involvement or/and international regulation bodies.[4]
Hardin's work has been criticised on the grounds of historical inaccuracy, and for failing to distinguish between common property and open access resources. While Hardin recommended that the tragedy of the commons could be prevented by either more government regulation or privatizing the commons property, subsequent Nobel Prize-winning work by Elinor Ostrom suggests that handing control of local areas to national and international regulators can create further problems.[5][6] Ostrom argues that the tragedy of the commons may not be as prevalent or as difficult to solve as Hardin implies, since locals have often come up with solutions to the commons problem themselves; when the commons is taken over by non-locals, those solutions can no longer be used.[5] Ostrom recognizes that there are real problems, and even limited situations where the tragedy of the commons applies to real-world resource management.[7]
As Hardin acknowledged[8] there was a fundamental mistake in the use of the term “commons." This was already noted in 1975 by Ciriacy-Wantrup & Bishop (1975: 714)[9] who wrote that we "are not free to use the concept 'common property resources' or 'commons' under conditions where no institutional arrangements exist. Common property is not 'everybody's property' (...). To describe unowned resource (res nullius) as common property (res communis), as many economists have done for years (...) is a self-contradiction." Neglecting the difference between common property and open access resources is a major reason of confusion in the debate that followed the 1968 Hardin's article.
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Thucydides (ca. 460 BC-ca. 395 BC) 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."[10]
Aristotle (384-322 BC) 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."[11]
In the 16th century School of Salamanca, Luis de Molina observed that individual owners take better care of their goods than they do of common property.
More recently, William Forster Lloyd noted the comparison with medieval village land holding in his 1833 book on population.[12]
Such a notion is not merely an abstraction, but its consequences have manifested literally in such common grounds as the Boston Common, where overgrazing led to discontinuation of the common's use as public grazing ground.[13] Radkau gives further, more positive examples and alleges the "real tragedy of the commons" to be ruthless use of common land motivated by agrarian reforms.[4]
At the beginning of his essay, Hardin draws attention to problems that cannot be solved by technical means, as distinct from those with solutions that require "a change only in the techniques of the natural sciences, demanding little or nothing in the way of change in human values or ideas of morality". Hardin contends that this class of problems includes many of those raised by human population growth and the use of the Earth's natural resources. The problem of population growth, Hardin asserts is endemic to society's inextricable ties to the welfare state.[14] Hardin says that a world in which individuals rely on themselves and not on the relationship of society and man, how many children a family would have would not be a public concern. Parents who breed excessively would leave fewer descendants because they would be unable to provide for each child adequately. Such negative feedback is found in the animal kingdom.[14] Hardin says that if the children of improvident parents starved to death, if overbreeding was its own punishment--then there would be no public interest in controlling the breeding of families.[14] For Hardin, it is the welfare state that allows the tragedy of the commons; where the state provides for children and supports overbreeding as a fundamental human right, malthusian catastrophe is inevitable. Hardin laments this interpretation of The Universal Declaration of Human Rights:
The Universal Declaration of Human Rights describes the family as the natural and fundamental unit of society. [Article 16[15]] It follows that any choice and decision with regard to the size of the family must irrevocably rest with the family itself, and cannot be made by anyone else.
This parental reproductive freedom was endorsed by the 1968 UN Proclamation of Tehran. Hardin advocates repudiation of this element of the Proclamation.[14]
To make the case for "no technical solutions," Hardin notes the limits placed on the availability of energy (and material resources) on Earth, and also the consequences of these limits for "quality of life." To maximize population, one needs to minimize resources spent on anything other than simple survival, and vice versa. Consequently, he concludes that there is no foreseeable technical solution to increasing both human populations and their standard of living on a finite planet.
From this point, Hardin switches to non-technical or resource management solutions to population and resource problems. As a means of illustrating these, he introduces a hypothetical example of a pasture shared by local herders, which he calls a commons. Assuming that the herders only wish is yield maximization, they will increase their herd size whenever possible. The marginal utility of each additional animal has both a positive and negative component:
Crucially, division of these costs and benefits is unequal: the individual herder gains all of the advantage, but the disadvantage is shared among all herders using the pasture. Assuming that the negative impact on the herder's other animals is less than the income of a new one, the rational course of action for each individual herder will always be herd expansion. Since all herders reach the same conclusion, overgrazing is inevitable. Each herder will continue to impose costs on all of the others, until the pasture is depleted.
Because this sequence of events follows predictably from the behavior of the participants, Hardin describes it as a "tragedy."
In the course of his essay, Hardin develops the theme, drawing in examples of latter day "commons," such as the atmosphere, oceans, rivers, fish stocks, national parks, advertising, and even parking meters. The example of fish stocks had led some to call this the "tragedy of the fishers."[17] Throughout the essay the impact of human population growth is a concern, with the Earth's resources being a general common.
The essay addresses potential management solutions to commons problems including privatization, polluter pays, and regulation. Keeping with his original pasture analogy, Hardin categorizes these as effectively the "enclosure" of commons, and notes a historical progression from the use of all resources as commons (unregulated access to all) to systems in which commons are "enclosed" and subject to methods of regulated use in which access is prohibited or controlled. Hardin argues against relying on conscience as a means of policing commons, suggesting that this favors selfish individuals — often known as free riders — over those who are more altruistic.
In the context of avoiding over-exploitation of common resources, Hardin concludes by restating Hegel's maxim (which was quoted by Engels), "freedom is the recognition of necessity." He suggests that "freedom" completes the tragedy of the commons. By recognizing resources as commons in the first place, and by recognizing that, as such, they require management, Hardin believes that humans "can preserve and nurture other and more precious freedoms."
Aside from its subject matter (resource use), the essay is notable (at least in modern scientific circles) for explicitly dealing with issues of morality, and doing so in one of the scientific community's premier journals, Science. Indeed, the subtitle for the essay is "The population problem has no technical solution; it requires a fundamental extension in morality."
The metaphor illustrates the argument that free access and unrestricted demand for a finite resource ultimately reduces the resource through over-exploitation, temporarily or permanently. This occurs because the benefits of exploitation accrue to individuals or groups, each of whom is motivated to maximize use of the resource to the point in which they become reliant on it, while the costs of the exploitation are borne by all those to whom the resource is available (which may be a wider class of individuals than those who are exploiting it). This, in turn, causes demand for the resource to increase, which causes the problem to snowball to the point that the resource is depleted (even if it retains a capacity to recover). The rate at which depletion of the resource is realized depends primarily on three factors: the number of users wanting to consume the common in question, the consumptiveness of their uses, and the relative robustness of the common.[18]
Like William Lloyd and Thomas Malthus before him, Hardin was primarily interested in the problem of human population growth. In his essay he also focused on the use of larger (though still limited) resources such as the Earth's atmosphere and oceans, as well as pointing out the "negative commons" of pollution (i.e., instead of dealing with the deliberate privatization of a positive resource, a "negative commons" deals with the deliberate commonization of a negative cost, pollution).
As a metaphor, the tragedy of the commons should not be taken too literally. The phrase is shorthand for a structural relationship and the consequences of that relationship, not a precise description of it. The "tragedy" should not be seen as tragic in the conventional sense, nor must it be taken as condemnation of the processes that are ascribed to it. Similarly, Hardin's use of "commons" has frequently been misunderstood, leading Hardin to later remark that he should have titled his work "The Tragedy of the Unregulated Commons".[19]
The tragedy of the commons has particular relevance in analyzing behavior in the fields of economics, evolutionary psychology, game theory, politics, taxation, and sociology. Some also see it as an example of emergent behavior, with the "tragedy" the outcome of individual interactions in a complex system.
Hardin's essay has been widely criticized. Public policy experts have argued that Hardin's account of the breakdown of common grazing land was inaccurate, and that such commons were effectively managed to prevent overgrazing.[20] Referring to Hardin's crucial passage on page 1244,17 Partha Dasgupta, for example, comments that "it is difficult to find a passage of comparable length and fame that contains so many errors as the one quoted."[21]
More significantly, criticism has been fueled by the application of Hardin's ideas to current policy issues. In particular, some authorities have read Hardin's work as specifically advocating the privatization of commonly owned resources. Consequently, resources that have traditionally been managed communally by local organizations have been enclosed or privatized. Ostensibly, this serves to protect such resources, but it ignores the pre-existing management, often appropriating resources and alienating indigenous (and frequently poor) populations. In effect, private or state use may result in worse outcomes than the previous management of commons.[22]
Some of this controversy stems from disagreement over whether individuals will always behave in the selfish fashion posited by Hardin. Others[23] have argued that even self-interested individuals will often find ways to cooperate, because collective restraint serves both the collective and individual interests. Hardin's piece has also been criticised as promoting the interests of Western economic ideology. G. N. Appell, an anthropologist, states: "Hardin's claim has been embraced as a sacred text by scholars and professionals in the practice of designing futures for others and imposing their own economic and environmental rationality on other social systems of which they have incomplete understanding and knowledge."[24]
Hardin's advocacy of clearly defined property rights has frequently been used as an argument for privatization, or private property, per se. The opposite situation to a tragedy of the commons is sometimes referred to as a tragedy of the anticommons: a situation in which rational individuals (acting separately) collectively waste a given resource by under-utilizing it.
The tragedy of the commons can be considered in relation to environmental issues such as sustainability. The commons dilemma stands as a model for a great variety of resource problems in society today, such as water, land, fish, and non-renewable energy sources such as oil and coal.
Situations exemplifying the "tragedy of the commons" include the overfishing and destruction of the Grand Banks, the destruction of salmon runs on rivers that have been dammed – most prominently in modern times on the Columbia River in the Northwest United States, and historically in North Atlantic rivers – the devastation of the sturgeon fishery – in modern Russia, but historically in the United States as well – and, in terms of water supply, the limited water available in arid regions (e.g., the area of the Aral Sea) and the Los Angeles water system supply, especially at Mono Lake and Owens Lake.
Other situations exemplifying the "tragedy of the commons" include pollution caused by driving cars. There are many negative externalities of driving; these include congestion, carbon emissions, and traffic accidents. For example, every time 'Person A' gets in a car, it becomes more likely that 'Person Z' – and millions of others – will suffer in each of those areas.[25]
More general examples (some alluded to by Hardin) of potential and actual tragedies include:
Articulating solutions to the tragedy of the commons is one of the main problems of political philosophy. In absence of enlightened self-interest, some form of authority or federation is needed to solve the collective action problem. In a typical example, governmental regulations can limit the amount of a common good available for use by any individual. Permit systems for extractive economic activities including mining, fishing, hunting, livestock raising and timber extraction are examples of this approach. Similarly, limits to pollution are examples of governmental intervention on behalf of the commons. Alternatively, resource users themselves can cooperate to conserve the resource in the name of mutual benefit.
Another solution for certain resources is to convert common good into private property, giving the new owner an incentive to enforce its sustainability. Effectively, this is what took place in the English Inclosure Acts. Increasingly, many agrarian studies scholars advocate studying traditional commons management systems to understand how common resources can be protected without alienating those whose livelihoods depend upon them.
An opposing idea, used by the United Nations Moon Treaty, Outer Space Treaty and Law of the Sea Treaty as well as the UNESCO World Heritage Convention involves the international law principle that designates certain areas or resources the Common Heritage of Mankind.[31]
Libertarians and classical liberals often cite the tragedy of the commons as an example of what happens when Lockean property rights to homestead resources are prohibited by a government.[32][33][34] These people argue that the solution to the tragedy of the commons is to allow individuals to take over the property rights of a resource, that is, privatizing it.[35] In 1940 Ludwig von Mises wrote concerning the problem:
If land is not owned by anybody, although legal formalism may call it public property, it is used without any regard to the disadvantages resulting. Those who are in a position to appropriate to themselves the returns — lumber and game of the forests, fish of the water areas, and mineral deposits of the subsoil — do not bother about the later effects of their mode of exploitation. For them, erosion of the soil, depletion of the exhaustible resources and other impairments of the future utilization are external costs not entering into their calculation of input and output. They cut down trees without any regard for fresh shoots or reforestation. In hunting and fishing, they do not shrink from methods preventing the repopulation of the hunting and fishing grounds.[36]
An objection to the privatization approach is that many commons (such as the ozone layer or global fish populations) would be extremely difficult or impossible to privatize.
Psychologist Dennis Fox used a number, what is now termed "Dunbar's number", to take a new look at the tragedy of the commons. In a 1985 paper titled "Psychology, Ideology, Utopia, & the Commons", he stated "Edney (1980, 1981a) also argued that long-term solutions will require, among a number of other approaches, breaking down commons into smaller segments. He reviewed experimental data showing that cooperative behavior is indeed more common in smaller groups. After estimating that "the upper limit for a simple, self-contained, sustaining, well-functioning commons [sic] may be as low as 150 people" (1981a, p. 27).
Costa Rica has successfully advanced the growth of its ecotourism business by taking account of, and pricing for, the environmental business services consumed by pollution.[37] The Coast Salish managed their natural resources in a place-based system in which families were responsible for looking after a place and its resources.[38] Access to food was the major source of wealth and the empowerment of generosity was highly valued, so it made sense for them to take care of the resources.
The "Coasian" solution to the problem is also a popular one, whereby the people formerly using the common each gain their own individual part of it instead — so it is no longer a common — and do not have to support one another so as not to deplete the resource.
In Hardin's essay, he proposed that the solution to the problem of overpopulation must be based on "mutual coercion, mutually agreed upon" and result in "relinquishing the freedom to breed". Hardin discussed this topic further in a 1979 book, Managing the Commons, co-written with John A. Baden.[39] He framed this prescription in terms of needing to restrict the "reproductive right" in order to safeguard all other rights. Only one large country has adopted this policy, the People's Republic of China. In the essay, Hardin had rejected education as an effective means of stemming population growth. Since that time, it has been shown that increased educational and economic opportunities for women correlates well with reduced birthrates in most countries, as does economic growth in general. However, given the nature of the problem as a limit to a given common resource, economic growth resulting in a higher per capita use of the resource may more than offset the decreased population growth's effect on total resource consumption. Note, however, that this now becomes a problem of economic expectations of a given population, and the problem of birth regulation appears to be eliminated.
The tragedy of the commons is referred to in studies of evolutionary biology, social evolution, sociobiology and behavioral ecology. A tragedy of the commons is brought about by selfish individuals whose genes for selfish behaviour would therefore come to predominate, so the metaphor cannot explain how altruism arises. This question is addressed instead by models of possible mechanisms that can give rise to "reciprocal altruism," leading to ideas like the "tit for tat" rule (reciprocation). These models freed evolutionary theory from the limitations imposed by the concept of "inclusive fitness," a previous explanation for altruism, which proposed that organisms help others only to the extent that by doing so they increase the probability of passing shared genes to the next generation.
A parallel was drawn recently between the tragedy of the commons and the competing behaviour of parasites that through acting selfishly eventually diminish or destroy their common host.[40]
The idea has also been applied to areas such as the evolution of virulence or sexual conflict, where males may fatally harm females when competing for matings.[41] It is also raised as a question in studies of social insects, where scientists wish to understand why insect workers do not undermine the "common good" by laying eggs of their own and causing a breakdown of the society.
The idea of evolutionary suicide, where adaptation at the level of the individual causes the whole species or population to be driven extinct, can be seen as an extreme form of an evolutionary tragedy of the commons.[42][43]
The commons dilemma is a specific class of social dilemma in which people's short-term selfish interests are at odds with long-term group interests and the common good. In academia, a range of related terminology has also been used as shorthand for the theory or aspects of it, including resource dilemma, take-some dilemma, and common pool resource.
Commons dilemma researchers have studied conditions under which groups and communities are likely to under- or over-harvest common resources in both the laboratory and field. Research programs have concentrated on a number of motivational, strategic, and structural factors that might be conducive to management of commons.
In game theory, which constructs mathematical models for individuals' behavior in strategic situations, the corresponding "game", developed by the ecologist Garrett Hardin, is known as the Commonize Costs — Privatize Profits Game (CC–PP game).
Strategic factors also matter in commons dilemmas. One often-studied strategic factor is the order in which people take harvests from the resource. In simultaneous play, all people harvest at the same time, whereas in sequential play people harvest from the pool according to a predetermined sequence — first, second, third, etc. There is a clear order effect in the latter games: the harvests of those who come first — the leaders — are higher than the harvest of those coming later — the followers. The interpretation of this effect is that the first players feel entitled to take more. With sequential play, individuals adopt a first come-first served rule, whereas with simultaneous play people may adopt an equality rule. Another strategic factor is the ability to build up reputations. Research found that people take less from the common pool in public situations than in anonymous private situations. Moreover, those who harvest less gain greater prestige and influence within their group.
Much research has focused on when and why people would like to structurally rearrange the commons to prevent a tragedy. Hardin stated in his analysis of the tragedy of the commons that "Freedom in a commons brings ruin to all."[44] One of the proposed solutions is to appoint a leader to regulate access to the common. Groups are more likely to endorse a leader when a common resource is being depleted and when managing a common resource is perceived as a difficult task. Groups prefer leaders who are elected, democratic, and prototypical of the group, and these leader types are more successful in enforcing cooperation. There is a general aversion to autocratic leadership, although it may be an effective solution, possibly because of the fear of power abuse and corruption.
The provision of rewards and punishments may also be effective in preserving common resources. Selective punishments for overuse can be effective in promoting domestic water and energy conservation — for example, through installing water and electricity meters in houses. Selective rewards work, provided that they are open to everyone. An experimental carpool lane in the Netherlands failed because car commuters did not feel they were able to organize a carpool. The rewards do not have to be tangible. In Canada there is a movement to put "smiley faces" on electricity bills if you are below the average for your class.[45] Much field research on commons dilemmas has combined solutions obtained in experimental research. Elinor Ostrom, who was awarded 2009's Nobel Prize of Economics for her work on the issue, and her colleagues looked at how real-world communities manage communal resources, such as fisheries, land irrigation systems, and farmlands, and they identified a number of factors conducive to successful resource management. One factor is the resource itself; resources with definable boundaries (e.g., land) can be preserved much more easily. A second factor is resource dependence; there must be a perceptible threat of resource depletion, and it must be difficult to find substitutes. The third is the presence of a community; small and stable populations with a thick social network and social norms promoting conservation do better.[46] A final condition is that there be appropriate community-based rules and procedures in place with built-in incentives for responsible use and punishments for overuse.
Tragedy of the commons is one of four outcomes:
| Property rights | Common ownership or lack of property rights | |
|---|---|---|
| Bad outcome/tragedy | Tragedy of the anticommons | Tragedy of the commons |
| Good outcome/cornucopia | normal case | Inverse commons |
The prevalent outcome depends on the details of the situation. The opposite outcome to the tragedy is the "comedy of the commons"[47] or "Inverse commons", in which network effects or other causes enhance the value of rivalrous resources because of the lack of regulation or private ownership.
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