Nonuniqueness of solutions in applied general equilibrium models with scale economies and imperfect competition

Applied general equilibrium models with imperfect competition and economies of scale have been extensively used for analyzing international trade and development policy issues. They offer a natural framework for testing the empirical relevance of propositions from the industrial organization and new trade theoretical literature. This paper warns model builders and users that considerable caution is needed in interpreting the results and deriving strong policy conclusions from these models: in this generation of applied general equilibrium models, nonuniqueness of equilibria is not a theoretical curiosum, but a potentially serious problem. Disregarding this may lead to dramatically wrong policy appraisals.