To further explore the tragedy of the commons and collective action, we turn to the topic of boundaries. Boundaries are critical for understanding what commons are and how collective action works. In the beginning of his depiction of the pasture and its herdsmen, Hardin (1968: 1244) asks the reader to “picture a pasture open to all”. “Open to all” means an absence of boundaries that would limit access to the pasture. In Governing the Commons, Ostrom (1990) argued for the feasibility of community-based resource management by presenting a set of design principles that can help communities overcome collective action problems involved in managing shared resources. These principles are Ostrom's most famous theoretical contribution to the study of environmental policy and governance. I refer to these throughout this book and a version of them based on my own work (Cox, Arnold & Villamayor-Tomas 2010) is included in the Appendix. Ostrom's first principle (which is divided into two in the Appendix) calls for clear social boundaries around legitimate users to distinguish them from non-users, and for biophysical boundaries around community-owned resources. The combination of social boundaries that define who is in and who is out, and biophysical boundaries indicating which parts of the environment are accessible by those who are “in”, is one way to define environmental property rights.

This chapter explores the importance of social boundaries as a key factor in promoting collective action by looking at the relationship between cooperation within groups and cooperation and conflict between groups. We will see that boundaries play the same role within the context of environmental property as they do in the context of collective action theory. The later parts of the chapter explore different types of boundaries and the roles they play. Here we first explore the difference between rigid and contextual boundaries, and we conclude the chapter with a discussion of general purpose versus special purpose boundaries as a way to understand the concept of common property, or the collective ownership of a resource by a group.