Sylos Labini’s essay is devoted to the analysis of price determination under condition of monopoly and monopsony. The problem of price indeterminacy in case of bilateral monopoly (associated with monopsony) is thoroughly discussed in relation to the market for goods and factors of production. The various cases are examined by assuming the hypothesis of ‘contracting parties’ ignorance
of each other’s price elasticities. In the last two sections of the paper, the A. make use of his analysis of monopoly and monopsony to dismiss the ‘Classical’ argument that a perfect wage flexibility can bring about a full employment equilibrium and offers his own interpretation of Keynes’s underemployment equilibrium grounded not on monetary factors but upon market structures. Sylos Labini offers a fresh perspective on the issues he was about to present in his major work Oligopolio e Progresso Tecnico (1956).