Common Property Externalities: Isolation, Assurance, and Resource Depletion in a Traditional Grazing Context
指出公地悲剧并非囚徒困境，而是保证问题，强调群体通过制度创新减少不确定性、协调预期，可解决过度开发问题，私有产权只是众多方案之一。
Abstract Institutional alternatives to common property externalities are wider than argued by private exclusive property rights advocates. The “tragedy of the commons” is not a prisoners' dilemma, characterized by the strict dominance of individual strategies. The nonseparable common property externality is an “assurance problem.” The assurance problem provides striking perspectives in analytical and policy terms. It redefines the problem of the commons as one of decision making under uncertainty. Institutional rules innovated by the group to reduce uncertainty and coordinate expectations can solve the problem of overexploitation. Rules come in many forms, and private property is only one.