Wassily Leontief and Léon Walras: the Production as a Circular Flow

Leontief’s input-output models are usually viewed as simplified classical (neo-Ricardian) models. However, this interpretation hides two opposed views. On the one hand, the common interpretation, based on Koopmans and Samuelson’s works, considers the so-called “models of Leontief” as simplified Ricardian models, in the sense of Samuelson, which are shown to be special cases of general equilibrium theory. In their framework, general equilibrium theory might be interpreted as a generalized model of Leontief and, reversely, models of Leontief are simplified Walrasian general equilibrium models. According to this theoretical tradition, classical theory and Walrasian general equilibrium theory are intimately linked and Classical economics is an “archaic” general equilibrium theory. On the other hand, neo-Ricardians view models of Leontief as simplified classical models that are incompatible with Walras’ general equilibrium theory. Our paper examines in details the last argument: the incompatibility argument. Such a work will require to examine in details the definition of vague categories as "Walrasian", "Classical" and so forth. We show that incompatibility between models of Leontief and Walras’ general equilibrium theory is ultimately based on Sraffa’s worldview: “The connection of [my] work with the theories of the old classical economists has been alluded to in the preface... It is of course in Quesnay’s Tableau Economique that is found the original picture of the system of production and consumption as a circular process, and it stands in striking contrast to the view presented by modern theory of a one-way avenue that leads from ‘Factors of production’ to ‘Consumption goods’.” (Sraffa, 1960) Neo-Ricardian’s opposition between classical economics and Walrasian theory is based on the representation of production: classical economics refers to circular flow while Marginalist theory refers to a one-way avenue production process. As it makes a sharp distinction between the two theoretical traditions, we call this criterion "Sraffa’s Guillotine". Based on Leontief’s PhD dissertation (1928) and his early input-output model (1937), the main result of our inquiry is that this criterion is powerless to distinguish Leontief’s representation of production as a circular flow and Walras one. Indeed, while Leontief based his models on Marx’ reproduction scheme, his representation of production is the same than Walras’ complete one, in striking contrast with neo-Ricardian critical apparatus. Hence we argue in favor of a pluralist interpretation of the models of Leontief: both Classical and Walrasians.