A Survey of the Theory of International Trade: Part 3, The Modern Theory

THE CELEBRATED factor price equalization theorem has a curious history. Ohlin (1933) introduced to English-speaking readers an important modification to international trade theory, replacing the classical simplification, of constant costs but differing production functions among countries, with the alternative simplification of identical production functions but differing factor endowments. While many economists have remarked on the unrealism of Ohlin's simplification, an important aspect of it has not, it would seem, always been sufficiently appreciated. This is the fact that the classical model assumed that production relations in different countries differed in a quite arbitrary fashion; no satisfactory way had been provided for explaining how such production relations differed. In the Ohlin model, on the other hand, an element of continuity was introduced, since continuous variation of factor endowments would yield continuous (rather than arbitrary) variation in production relations. Even if differences in production relations (specifically, in transformation functions) cannot be completely explained in terms of differences in factor endowments, the Ohlin model is nevertheless susceptible to amendments that preserve meaningful relationships between different countries' production functions. Ohlin's writings were greatly influenced by Heckscher (1919), whose work was not made available in English until 1949. Heckscher, in turn, acknowledged the influence on his thought of Wicksell (1919).' Ohlin asserted that there was a tendency towards factor price equalization as a result of free trade, but he tempered his argument with many qualifications, even to the point of asserting that equalization would never be complete. The partial equalization argument was taken up and made rigorous by Stolper and Samuelson (1941), and later Samuelson (1948,