Consumption externalities, production externalities, and long-run macroeconomic efficiency

We analyze the effects of consumption and production externalities on capital accumulation. We show that the importance of consumption externalities depends upon the elasticity of labor supply. If the labor supply is inelastic, consumption externalities cause no long-run distortions. Whether there are distortions along the transitional path depends upon consumer preferences. The effects of production externalities are more pervasive; they exert long-run distortionary effects irrespective of labor supply. The optimal taxation to correct for the distortions created by the externalities is characterized. We analyze both stationary and endogenously growing economies, and while there are many parallels in how externalities impact, there are also important differences.