How Would David Ricardo Have Taught the Principle of Comparative Advantage?

Abstract

If David Ricardo had lived beyond the age of 51, how might he have delivered a lecture on comparative advantage? I argue that Ricardo infers the direction of comparative advantage and the size of the gains from trade by interpreting the four numbers in his Principles of Political Economy and Taxation for cloth and wine traded between England and Portugal as amounts of labor embodied in the quantities actually traded. He illustrates diagrammatically the gains from trade as the overall labor that England would save if it were to liberalize wheat imports by repealing the Corn Laws. Postulating a concave production function for wheat, Ricardo also depicts the concomitant rise in the profit rate, describing it as an equally important contemporary gain from trade for England. His interpretation differs radically from the textbook versions of the “Ricardian trade model,” and suggests a more authentic way of presenting the principle of comparative advantage.