The escape from conjectural variations: the consistency condition in duopoly theory from Bowley to Fellner

The paper covers the 1924--1949 debate on the conjectural variations approach to duopoly theory and focuses on the evolution of economists' views about the imposition of a consistency condition on the firms' conjectures. The main point is that, although the consistency condition entailed a notion of interactive equilibrium that resembled the modern correct conjectures equilibrium, most neoclassical economists of the time refused to apply it because of the excessive requirements it imposed upon the firms' forecasting abilities, and because of its failure to encompass an explanation of the equilibrating process. Copyright 2005, Oxford University Press.