Scale Economies, Product Differentiation, and the Pattern of Trade

For some time now there has been considerable skepticism about the ability of comparative cost theory to explain the actual pattern of international trade. Neither the extensive trade among the industrial countries, nor the prevalence in this trade of two-way exchanges of differentiated products, make much sense in terms of standard theory. As a result, many people have concluded that a new framework for analyzing trade is needed.' The main elements of such a framework-economies of scale, the possibility of product differentiation, and imperfect competition-have been discussed by such authors as Bela Balassa, Herbert Grubel (1967,1970), and Irving Kravis, and have been "in the air" for many years. In this paper I present a simple formal analysis which incorporates these elements, and show how it can be used to shed some light on some issues which cannot be handled in more conventional models. These include, in particular, the causes of trade between economies with similar factor endowments, and the role of a large domestic market in encouraging exports. The basic model of this paper is one in which there are economies of scale in production and firms can costlessly differentiate their products. In this model, which is derived from recent work by Avinash Dixit and Joseph Stiglitz, equilibrium takes the form of Chamberlinian monopolistic competition: each firm has some monopoly power, but entry drives monopoly profits to zero. When two imperfectly competitive economies of this kind are allowed to trade, increasing returns produce trade and gains from trade even if the economies have identical tastes, technology, and factor endowments. This basic model of trade is presented in Section I. It is closely related to a model I have developed elsewhere; in this paper a somewhat more restrictive formulation of demand is used to make the analysis in later sections easier. The rest of the paper is concerned with two extensions of the basic model. In Section II, I examine the effect of transportation costs, and show that countries with larger domestic markets will, other things equal, have higher wage rates. Section III then deals with "home market" effects on trade patterns. It provides a formal justification for the commonly made argument that countries will tend to export those goods for which they have relatively large domestic markets. This paper makes no pretense of generality. The models presented rely on extremely restrictive assumptions about cost and utility. Nonetheless, it is to be hoped that the paper provides some useful insights into those aspects of international trade which simply cannot be treated in our usual models.