Commons

Shared resources that are rivalrous but non-excludable — where one person’s use diminishes availability for others, yet access cannot easily be restricted.

Classic examples: fisheries, pastures, aquifers, atmosphere. The “tragedy of the commons” (Hardin) describes overexploitation when individual incentives conflict with collective sustainability. Ostrom showed commons can be sustainably managed through appropriate institutions.

Systems Connection

A commons is a system where components (users) draw from shared state (the resource stock). Without governance, feedback is delayed — individual benefit is immediate while collective cost is distributed. Sustainable commons management requires institutional structures that internalize externalities.

Ostrom’s Design Principles

• Clear boundaries — who can access
• Proportional feedback — rules match local conditions
• Polycentric monitoring and enforcement

See Also

• Political Economy — parent domain
• Collective Action — the underlying problem
• Public Goods — related resource type
• Polycentric Governance — Ostrom’s solution