Hardin's "Tragedy of the Commons" (1968): shared resources are overexploited because each user captures the full benefit of their use while sharing the costs with everyone.

The paper was influential and partly wrong. Elinor Ostrom (Nobel 2009) documented dozens of cases where communities successfully managed commons without privatization or central regulation — through local norms, monitoring, and graduated sanctions.

The tragedy occurs when communities lack the ability to communicate, monitor, and exclude. It's not an inevitable property of shared resources.

Related: [[coordination-problems]]