Basic definitions

• Commons: shared stuff that requires social agreement (whether tacit or explicit) for its sustainable management.

• social dilemma: a collective action situation in which there is a conflict between individual and collective interest. It is a situation in which individuals could do better if they either changed their strategies or changed the rules of the game.

• resource system/units: a resource system generates a flow of resource units over time. Resource systems are things like lakes, groundwater basins, forests, and pasturelands, and their corresponding resource units include fish, water, trees, and fodder. Some resource systems are called Commons.