Private provision of public goods can be efficient

Economists have long believed that private provision of public goods will be inefficient, though recently some have argued that altruism may mitigate the inefficiencies. Without altruism, agents contribute to the point where marginal cost equals their private marginal benefits. With altruism, they contribute more and hence are closer to the point where marginal cost and total marginal benefits are equated. In an earlier paper (Bagnoli and Lipman, 1989), we showed that private provision need not be inefficient. In a very natural model of private provision without altruism, we showed that the set of (undominated perfect) equilibrium outcomes is identical to the core. Here we consider the effect of altruism on private provision. Altruism essentially creates more public goods because the well-being of others becomes a public good. We show that our model of private provision still has efficient equilibria under a wide variety of circumstances. Interestingly, the equilibria may be inefficient when agents are concerned about the effect of private provision on the distribution of wealth. Intuitively, the game we consider is a very powerful instrument for efficient private provision, but must be supported by other instruments if the set of public goods is expanded too far.We wish to thank Jim Andreoni, Ted Bergstrom, and an anonymous referee for helpful comments and to acknowledge financial support from the National Science Foundation through NSF Grant SES-8520296. Of course, any remaining errors are our responsibility.