Ramsey's theory of National Saving: A Mathematician in Cambridge

Abstract

In the December 1928 issue of the Economic Journal, Frank Ramsey asked the question “how much of its income should a nation save?” Few of the Cambridge economists of the 1930s were convinced by his highly formalized answer. His contribution sank quickly into oblivion, remaining there for about thirty-five years. In the 1960s, the success of the Hamiltonian formalism and the increasing interest for optimal growth led on the contrary to a quasi “natural” use of Ramsey's former intuitions. These mathematical tools became so widespread that, a few years later, new classical macroeconomics uses a new interpretation of the “à la Ramsey” models, within the setting of representative agent models, in order to bypass the Arrow and Sonnenschein-Mantel-Debreu “impossibility results.” The “à la Ramsey” model is the backbone of modern new classical macroeconomics. It is thus not surprising that these successive moves in macro-economic theory came to foster a slanted interpretation of Ramsey's 1928 article. In this respect, Roger E. A. Farmer's point of view is representative of the retrospective tribute sometimes paid to Ramsey's article:F. Ramsey was one of the first economists to study how an infinitely lived agent should allocate his resources over time. His work was at the forefront of mathematical economics at the time it was written but his approach has now become a standard part of graduate macroeconomic courses. Many applications of Ramsey's work assume that there is only one agent in the economy and that this representative agent can be thought of as a stand-in for the workings of the market mechanism (Farmer 1993, p. 77).