Endogenous Growth, Temporary Equilibrium, and the Direction of Change

This article studies the long-run direction of technological change in an endogenous growth model. Development is modeled as a sequence of temporary equilibria in an overlapping generations framework. We introduce a concept of `long-run efficient development' which excludes persistent inefficiencies. The concept is much weaker than short-run or long-run Pareto-efficiency and does not depend on our particular model. The main theorem of the article gives conditions on agents' expectations and preferences and on the evolution of innovation possibilities under which equilibrium development, guided by current prices and profit expectations, is long-run efficient.