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, microbiologist and ethno-nationalist 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". On the same grounds, Hardin argued that rich countries should adopt lifeboat ethics ending aid to the poor and stopping migration from poor countries.
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 eugenicist and racist.
Expositions
Classical The concept of unrestricted-access resources becoming spent, where personal use does not incur personal expense, was discussed by the philosopher Aristotle, who observed in his Politics that
Lloyd's pamphlet In 1833, the English economist William Forster Lloyd published "Two Lectures on the Checks to Population", a pamphlet that included a hypothetical example of over-use of a common resource. This was the situation of cattle herders sharing a common parcel of land on which they were each entitled to let their cows graze.
He postulated that if a herder put more than his allotted number of cattle on the common, overgrazing could result. For each additional animal, a herder could receive additional benefits, while the whole group shared the resulting damage to the commons. If all herders made this individually rational economic decision, the common could be depleted or even destroyed, to the detriment of all.
Lloyd's pamphlet was written after the enclosure movement had eliminated the open field system of common property as the standard model for land exploitation in England (though there remained, and still remain, millions of acres of "common land": see ). Carl Dahlman and others have asserted that his description was historically inaccurate, pointing to the fact that the system endured for hundreds of years without producing the disastrous effects claimed by Lloyd.
Garrett Hardin's article In 1968, ecologist Garrett Hardin explored this social dilemma in his article "The Tragedy of the Commons", published in the journal Science. The essay derived its title from the pamphlet by Lloyd, which he cites, on the over-grazing of common land.
Hardin discussed 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 focused on human population growth, the use of the Earth's natural resources, and the welfare state.
Hardin argued that if individuals relied on themselves alone, and not on the relationship between society and man, then people would treat other people as resources, which would lead to the world population growing and for the process to continue. Parents breeding 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. Hardin said 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.
Political inferences
Hardin blamed the welfare state for allowing the tragedy of the commons; where the state provides for children and supports overbreeding as a fundamental human right, a Malthusian catastrophe is inevitable. Consequently, in his article, Hardin lamented the following proposal from the United Nations:
In addition, Hardin also pointed out the problem of individuals acting in rational self-interest by claiming that if all members in a group used common resources for their own gain and with no regard for others, all resources would still eventually be depleted. Overall, Hardin argued 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-pool resources, Hardin concluded by restating Hegel's maxim (quoted by Engels), "freedom is the recognition of necessity". He suggested 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 believed that humans "can preserve and nurture other and more precious freedoms".
The "Commons" as a modern resource concept Hardin's article marked the mainstream acceptance of the term "commons" as used to connote a shared resource. As Frank van Laerhoven and Elinor Ostrom have stated: "Prior to the publication of Hardin's article on the tragedy of the commons (1968), titles containing the words 'the commons', 'common pool resources', or 'common property' were very rare in the academic literature." They go on to say: "In 2002, Barrett and Mabry conducted a major survey of biologists to determine which publications in the twentieth century had become classic books or benchmark publications in biology. They report that Hardin's 1968 article was the one having the greatest career impact on biologists and is the most frequently cited". However, the Ostroms point out that Hardin's analysis was based on crucial misconceptions about the nature of common property systems.
System archetype
In systems theory, the commons problem is one of the ten most common system archetypes. The Tragedy of the Commons archetype can be illustrated using a causal loop diagram.
Application Metaphoric meaning
Like Lloyd and Thomas Malthus before him, Hardin was primarily interested in the problem of human population growth. But in his essay, he also focused on the use of larger (though finite) 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 "tragedy" is not in the word's conventional or theatric sense, nor a condemnation of the processes that lead to it. Similarly, Hardin's use of "commons" has frequently been misunderstood, leading him to later remark that he should have titled his work "The Tragedy of the Unregulated Commons".
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 maximise the 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 until the resource collapses (even if it retains a capacity to recover). The rate at which depletion of the resource is realised depends primarily on three factors: the number of users wanting to consume the common in question, the consumptive nature of their uses, and the relative robustness of the common.
The same concept is sometimes called the "tragedy of the fishers", because fishing too many fish before or during breeding could cause stocks to plummet.
Modern commons
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, forests, fish, and non-renewable energy sources such as oil, gas, and coal.
Hardin's model posits that the tragedy of the commons may emerge if individuals prioritise self-interest.
Another case study involves beavers in Canada, historically crucial for natives who, as stewards, organised to hunt them for food and commerce. Non-native trappers, motivated by fur prices, contributed to resource degradation, wresting control from the indigenous population. Conservation laws enacted in the 1930s in response to declining beaver populations led to the expulsion of trappers, legal acknowledgment of natives, and enforcement of customary laws. This intervention resulted in productive harvests by the 1950s.
Situations exemplifying the "tragedy of the commons" include the overfishing and destruction of the Grand Banks of Newfoundland, 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), and the devastation of the sturgeon fishery (in modern Russia, but historically in the United States as well). In terms of water supply, another example is 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) and in the Konya basin in Turkeybbc.com 25 June 2026: Droughts are transforming the Turkish landscape with massive sinkholes).
In economics, an externality is a cost or benefit that affects a party who did not choose to incur that cost or benefit. Negative externalities are a well-known feature of the "tragedy of the commons". For example, driving cars has many negative externalities; these include pollution, carbon emissions, and traffic accidents. Every time Person A gets in a car, it becomes more likely for Person Z to suffer in each of those areas. Economists often urge the government to adopt policies that "internalize" an externality.Jaeger, William. Environmental Economics for Tree Huggers and Other Skeptics, p. 80 (Island Press 2012): "Economists often say that externalities need to be 'internalized,' meaning that some action needs to be taken to correct this kind of market failure."
The tragedy of the commons can also refer to the idea of open data. Anonymised data are crucial for useful social research and represent therefore a public resource better said, a common good that is liable to exhaustion. Some feel that the law should provide a safe haven for the dissemination of research data, since it can be argued that current data protection policies overburden valuable research without mitigating realistic risks.