While the performance of peer-to-peer (p2p) systems largely depend on the cooperation of the member nodes, there is an inherent conflict between the individuals’ self interest and the communal social welfare. In this regard, many interesting parallels between p2p systems and cooperation in human societies can be drawn. On the one hand, human societies are organized around a certain level of altruistic behavior. Whilst, on the other hand, individuals tend to overuse public goods, if they are free to do so. This paper proposes a new incentive scheme that extracts and modifies sociological incentive patterns, based on the Tragedy of Commons analogy, to work efficiently in a p2p environment. It is shown through simulations that this scheme encourages honest peers whilst successfully blocking non-contributors.