Pure Public Goods versus Commons: Benefit-Cost Duality

This paper utilizes benefit-cost duality to differentiate the problems associated with a pure public good from the problems associated with a commons. For the public good scenario, contributorsʹ benefits are public or available to all, while provision costs impact only the contributor. In a commons, crowding costs are public, while benefits affect only the user. Although both problems possess the same game form for their canonical representations, collective-action implications differ: for example, the relative positions of the Nash equilibrium and Pareto optimum, the form of the exploitation hypothesis, and the need for selective incentives or punishments.