Say, Jean Baptiste (zhäN bätēstˈ sā) [key], 1767–1832, French economist. In A Treatise on Political Economy (1803, tr. from the 4th ed. 1821) he effectively reorganized and popularized the theories of Adam Smith. Say also developed a noted theory of markets and the concept of the entrepreneur. Say's law of markets holds that supply creates its own demand. His works include Cours complet d'économie politique pratique (6 vol., 1828–29).
His grandson, Léon Say, 1826–96, was also an economist. As minister of finance under several governments he accomplished the payment of war debts to Germany ahead of schedule. He edited and wrote several works on finance.
See study of J. B. Say by T. Sowell (1972).