What Is Garrett Hardin's Simple Mathematical Argument for the Inevitability of “Tragedy of the Commons"?
According to the commons theory, each individual gains much more than he or she loses by overusing a commonly held resource, so its destruction is simply an inevitable consequence of normal and rational behavior. In the study of economics, this idea is known as the free rider problem. Human population growth is the issue in which the commons idea is most often applied: each individual gains personal security and wealth by producing many children. Even though each additional child taxes the global community's food, water, energy, and material resources, each family theoretically gains more than it loses for each additional child produced. Although the theory was first published in the nineteenth century, Garrett Hardin introduced it to modern discussions of population growth in a 1968 article published in the journal Science. Since that time, the idea of the tragedy of the commons has been a central part of population theory. Many people insist that the logic of the commons is irrefutable; others argue that the logic is flawed and the premises questionable. Despite debates over its validity, the theory of the commons has become an important part of modern efforts to understand and project population growth.
The straightforward application of the "herdsman" analogy to world population is that each couple expects to experience a large benefit from having another child, but only a little of the full social and ecological cost. Both Hardin's solutions, and their weaknesses, stem from things assumed in this model. His basic solution is that we must abandon the commons system in breeding (as we have already in food production and pollution - instances where we have used privatization and laws to achieve this). People must no longer be free to add unlimited numbers of offspring to the total load on the earth's ecosystems. This sounds simple enough, but the key question is how this restriction is to be achieved. Hardin's rejection of some solutions stems from the individualistic assumptions of his metaphor. Particularly, he rejects appeals to conscience, because they would "select for" those without scruples over having more children. It is doubtful however that conscience is entirely genetic, nor perfectly transmitted by learning in families. Further, his assumption that were it not for "welfare," over-breeders would have to pay for their profligacy, runs in the face of evidence that parents whose infants die are paradoxically both more inclined to get pregnant again, and less likely to emotionally invest in their young. Welfare may indeed be part of solving the population problem. This is just one example where Hardin fails to differentiate reproductive behavior according to socio-economic conditions.
Fishes that aggregate to spawn in highly predictable parts of the environment are most susceptible, and regulations to protect spawning fishes can be useful.
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