Market forms and effective demand: Keynesian results with perfect competition

Abstract

In recent years there has been a flourishing of models with microfoundations based on imperfect (or monopolistic) competition that claim to yield Keynesian results which, it is held, are incompatible with perfect competi-tion. The paper shows that Keynes’s results do not depend on market forms but are contingent on his treatment of investment. In Keynes’s analysis, the existence of underemployment equilibria is demonstrated regardless of the assumed market form. Far from taking into account the importance of investment, recent models with ‘Keynesian results’ ignore investment altogether. The article argues that if the investment demand function, with its distinctive characteristics, is removed, involuntary unemployment can be explained only by imperfections or rigidities that prevent producers from pushing their supply up to the level of full employment. A conclusion that Keynes wanted to avoid. The introduction of a hypothesis of market forms different from imperfect competition may be useful in order to...