A form of economic analysis which argues that the economic value of a product is determined by the price or rate of exchange of the last unit supplied on the market.
Marginalism was developed independently by W. S. Jevons (1835–82), C. Menger (1840–1921), and M. E. L. Walras (1834–1910). It broke with the classical definition of value as the quantity of labour embodied in a product, and was thus an important component in the development of neoclassical economics.
Early 20th century; earliest use found in Journal of Political Economy. From marginal + -ism.