Keynes and the Marshall-Walras Divide

This paper is a sequel to De Vroey (1998d) and (1998e). In these papers, I pondered upon the relationship between the Marshallian and the Walrasian research programs and defended the view that a divide should be drawn between them, contrary to the opinion of the majority of economists who see no need for such. I argued that these research programs differ on two scores. First, they are based on different conceptions of equilibrium. Second, they differ on the way in which they broach the issue of the working of the decentralized economy. The hallmark of the Marshallian approach is that it proceeds in two steps. The working of particular markets is analyzed in a first stage whereas the issue of their coordination is assigned to the second stage of the inquiry. Contrarily, the hallmark of the Walrasian approach is to immediately start the analysis at the level of the economy as a whole. Put differently, in the Marshallian approach, partial equilibrium analysis is seen as a first preliminary step to general equilibrium analysis, whereas in the Walrasian approach one immediately proceeds with the latter. The aim of the present paper is to show the incidence of this twofold difference on the interpretation of Keynesian theory.