Common Pool Resources (CPRs) v. Common Property Regimes (CPRs)

In the social science literature, the abbreviation CPR stands for two related, but distinct, phrases that are too often conflated: common-pool resources and common-property regimes. Yesterday, at a conference at NYU Law School on "Convening Cultural Commons" (about which I previously posted here), a small and short debate arose between two scholars I greatly admire, Lin Ostrom and Carol Rose, about the two types of CPRs. Carol, if I understood her correctly, suggested that the distinction is insignificant because common-pool resources inevitably are defined as such within an institutional context. Lin responded that resource attributes such as relative subtractability and excludability, are not institutionally determined and play a crucial role in determining whether or not a resource is a commons.

Because the exchange was brief and, basically, an aside to other issues being addressed at the time, I hesitate to make too much of it. But I must say I find Carol's position baffling. An institutional structure - whether common-property, individual private-property, or some other management system - obviously affects rates of  extraction/resource-depletion. But it does not affect subtractability which depends exclusively on ecological circumstances.* Ecological circumstances can/should affect the applicable institutions, for reasons explained by Hardin (1968), Demsetz (1967) and many others. But institutions don't alter the fundamental ecological conditions. Put differently, a subtractable resource remains subtractable whether the current rate of demand, under prevailing institutional structures, is either zero or very high. (This is why Ostrom's social-ecological systems framework quite rightly pays as much attention to ecological conditions as to institutions.)

*Institutions can affect excludability, if only indirectly, by affecting incentives to innovate technologies that, themselves, can enhance excludability, at least with respect to some resources. Thus, the invention of barbed wire in the mid-19th century enhanced excludability of lands in the western US, where lack of timber had previously made enclosure too expensive (Anderson and Hill 1975).