Post-Keynesian Economics, Rationality, and Conventions

The role of conventions has been an area of increasing interest to writers in the post-Keynesian tradition, particularly over the last thirty years. This has arisen from the reexamination of John Maynard Keynes’s notion of convention in the context of radical uncertainty along with the status of rationality in the face of uncertainty. This chapter discusses some of the principal tenets of Henri Poincaré’s analysis of conventions and relates them to the post-Keynesian methodological agenda, more specifically to provide a Poincaréan defense of the role of conventions in rational decision-making. It argues that this provides an innovative and more adequate philosophical defense of nonergodicity in economic theory, which has become a central axiom of post-Keynesian economics. The chapter first provides an overview of the post-Keynesian literature on uncertainty and conventions arising from Keynes’s employment of the concept. It then outlines the emergence of conventions and conventionalism in philosophy, examines Poincaré’s conventionalism and its relationship with rationality, and considers the implications of Poincaré’s conventionalism for post-Keynesian economics.