Lewis, Sir Arthur (Sir William Arthur Lewis), 1915-91, British economist, b. St. Lucia. A graduate (1940) of the London School of Economics, he was later a professor of economics at the Univ. of Manchester (1948-58) and at Princeton Univ. (1963-83). A specialist in the economic theory of developing countries, he shared the 1979 Nobel Memorial Prize in Economic Sciences with American Theodore W. Schultz. Among his most important books are The Theory of Economic Growth (1955), Development Planning (1966), and Growth and Fluctuations, 1870-1913 (1978).