Finite Horizon, Externalities, and Growth

This paper investigates the impact of externalities on economic growth in an AK model. In contrast to the existing literature, the paper considers finitely-lived agents along the continuous time, overlapping generations literature. A series of new results, not holding for infinitely-lived agent economies, emerge. Consumption externalities generally introduce a distortion (inefficiency), even when labor supply is exogenous and there is no concurrent production externality. A negative consumption externality implies overconsumption, and growth is lower than optimal. Transition paths are considered. The model employed encompasses the infinitely-lived agent economy as a special case, thus helps understanding the differences in results between finite-horizon overlapping-generations and infinitely-lived agents economies.