When Ricardo Meets Chamberlin : A Simple Dynamic Model of Monopolistic Competition

We develop a dynamic model of monopolistic competition which sheds light on how the interplay between the degree of product differentiation and intertemporal elasticity of substitution affects the steady-state equilibrium. Consumers love variety and split their labor endowment between wage labor, which brings immediate income, and producing capital, which yields a rent in the future. The impact of the elasticity of substitution across varieties on the market outcome depends crucially on whether consumption today and consumption tomorrow are gross substitutes or gross complements. The case of Cobb-Douglas intertemporal utility is a borderline situation, when the market outcome is invariant to the degree of product differentiation. We also fully characterize the unique steady-state equilibrium path and show that the key dynamic properties of the model, such as local stability and determinacy of equilibrium, also hinge mainly on the interplay between the intra- and intertemporal elasticities of substitution