Say, Jean-Baptiste (1767-1832)
A practical businessman, Say developed an interest in economics and began lecturing in the subject in 1816. In 1819 he was appointed to the Chair of Industrial Economy at the Conservatoire National des Arts et Metiers. In 1831 he was appointed Professor of Political Economy at the College de France. His most important published works are Traite d’economie politique, which appeared in 1803, and Cours complet d ‘economie politique pratique, which was published in 1829. Although he can claim some credit for the introduction of the concept of an entrepreneur into economic theory, and also the division of the fundamental factos of production into three – land, labour and capital – his farne and notoriety spring from his ‘loi des debouches’, or ‘law of markets’. It is probable that his ‘law’ would not figure so prominently in economics today had not J. M. Keynes accused the classical school of being gravely misled by accepting it as the pivot of their macroeconomic theory. According to Keynes, the law said that the sum of the values of all commodities produced was equivalent (always) to the sum of the values of all commodities bought. By definition, therefore, there could be no underutilization of resources; ‘supply created its own demand’. However, there is some considerable doubt about what Say actually meant. Several versions have been put forward; some are incontrovertible platitudes, such as in barter a seller must also be a buyer, and if a good is sold somebody must have bought it. Probably the most meaningful interpretation is that of Keynes, but only as a condition which must be satisfied for equilibrium to exist.
Reference: The Penguin Dictionary of Economics, 3rd edt.