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Tragedy of the commons is a game theory concept highlighting the conflict between individual and collective rationality.

The idea of the tragedy of the commons was made popular by the American ecologist Garrett Hardin, who used the analogy of ranchers grazing their animals on a common field. When the field is not over capacity, ranchers may graze their animals with few limitations. However, the „rational“ rancher will seek to add livestock, thereby increasing profits. Thinking logically but not collectively, the benefits of adding animals adhere to the rancher alone, while the costs are shared. The tragedy is that ultimately no rancher will be able to graze the field, due to overconsumption. This scenario is played out on a daily basis in numerous instances, having grave consequences for the world’s resources.