>[W]hat prevents someone from starting a new PPL which
>protects you from local crime, and makes the appropriate agreements
>with other PPLs, but doesn't contribute to this defense "pool".
Three comments, in brief, appropos this old problem:
1) Excludability does not represent an essential quality; rather, it bears an
inverse relationship to cost. In other words, public goods change in the
face of changing technologies, with historical trends toward the
internalization of positive externalities. See, eg, broadcast-to-cable
transmissions. I'm unwilling to claim that noone can whup the "national"
defense problem.
2) Among the probable social technologies for internalizing the benefits of
"national" defense in a polycentric legal order, I would count social
sanctions, with voluntary donations to defense efficiently tracked and tied
to a variety of services. See, eg, the United Way's devices. Another
appealling device, especially to large legal systems paying for defense:
Peace. (Permit me, if you will, a "duh.")
3) Robin rightly doubts predictions about the end-state of the end of States.
Better to advocate jurisdiction based on express consent and let
entrepreneurs take a crack at such problems as national defense and
cross-jurisdictional conflicts. See, Why Respect the Law? The Polycentric
Justification of Jurisdiction</EM>, in EXTRO 1: Proceedings of the First
Extropy Institute Conference on Transhumanist Thought, at 46 (1994).
T.0. Morrow