We explain a counterintuitive empirical finding: Firms facing more import competition do more innovation. In our model, factors are trapped inside a firm. An increase in import competition encourages a firm to innovate by reducing the opportunity cost of inputs. Without trapped factors, trade...

There is substantial research about cross section and time series correlations between economic growth and various economic, social, demographic and political variables. After analyzing these correlations, the paper makes the following conclusions. Exogenous increases do not seem to cause...

We characterize equilibria of general equilibrium models with externalities and taxes as solutions to optimization problems. This characterization is similar to Negishi’s characterization of equilibria of economies without externalities or taxes as solutions to social planning problems. It is...

This paper describes two strands of work that converged under the heading of 'endogenous growth.' One strand, which is primarily empirical, asks whether there is a general tendency for poor countries to catch up with rich countries. The other strand, which is primarily theoretical, asks what...