The Tragedy of the Commons

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The Tragedy of the Commons takes the prisoner’s dilemma a step closer to how societies interact with their world(s). The concept was introduced in a lecture given by William Foster Lloyd at Oxford University in 1833. Intellectuals like Lloyd and Thomas Malthus (1766–1834) were alarmed at the likely outcome of unrestricted human population growth. In particular they contended that, if unchecked, global human population would increase geometrically (e.g., 2, 4, 8, 16…), whereas food supply would only grow arithmetically. Malthus predicted that food resources per capita would begin to diminish about the middle of the 19th Century. He failed however, to predict the effects of technological advances in agriculture.

In the application of the concept provided here, the world is an isolated island that can expect no assistance from outside. This parable allows us to envisage what may happen in a situation where individuals have free and unlimited access to limited resources.

The goat herder[edit | edit source]

A broad open pasture, suitable for goat grazing, is the only area of fertile ground on a small, isolated, but inhabited island. Over a period of several centuries, there is a gradual increase in the number of goats and the island families that they support. At one point in time, the carrying capacity of the land is reached, such that the addition of any further goats would lead to overgrazing. Jana, a herdsman, contemplates the situation and, after deliberation, decides to increase his own herd by one goat. Jana rationalises this, in terms of positive and negative elements, in the following way: The extra goat is good for him (and his family), as it increases his income by the proceeds that he will receive after sale of the animal. This can be viewed in broad terms as a ‘+ 1’ for him. Conversely, the effect of overgrazing by just one extra goat would be spread over all the goatherds, resulting in only a very small fraction of a ‘– 1’ being debited against him. The following year, Jana again decides to increase his herd by just one more goat, but this time, unbeknown to him, two of his cousins decide to do the same.

Considerations[edit | edit source]

  • What are the likely outcomes of Jana’s action?
  • Can Jana’s actions be justified from either a deontological or utilitarian approach?
  • The above scenario is termed the ‘Tragedy of the Commons’. What relevance (if any) does it have to developed nations?
  • Can logic (and history) allow us to predict that technological advances will always allow humans to keep ahead of Malthus’ point of diminishing returns?
  • If he had adhered to contractarian ethics, what would Jana have done in the above exemplar, and what would have been the likely outcomes?

Article taken with permission from: Buckeridge, J.St,J.S., 2008. 4 E's: Ethics, Engineering, Economics and Environment. RMIT University Press, Melbourne, Australia, pp 61-63.