Roger Guesnerie

Roger Guesnerie (17 February 1943 – 4 January 2026) was a French academic and economist. He was last the Chaired Professor of Economic Theory and Social Organization of the Collège de France, Director of Studies at the École des hautes études en sciences sociales, and the chairman of the board of directors of the Paris School of Economics.

Life and career Guesnerie was born in Sainte-Gemmes-le-Robert on 17 February 1943. He studied at École Polytechnique and the École Nationale des Ponts et Chaussées, and received his doctorate in economics from the University of Toulouse in 1982. He taught at the London School of Economics, the École Polytechnique, and at Harvard University. Guesnerie published widely in economics, including in public economics, in the theory of incentives and economic mechanisms, and in the theory of general economic equilibrium.

Guesnerie died in Paris on 4 January 2026, at the age of 82. "Assessing Rational Expectations 2: Eductive stability in economics", MIT Press, 2005, 453p. "Assessing Rational Expectations: Sunspot multiplicity and economic fluctuations", MIT Press, 2001, 319 p. "A contribution to the pure theory of taxation", Cambridge University Press, 1995, 301 pages

Papers

with Donald J. Brown credited Guesnerie's "seminal" paper with the "major methodological innovation in the general equilibrium analysis of firms with pricing rules", "the introduction of the methods of nonsmooth analysis, as a [synthesis] of global analysis (differential topology) and [of] convex analysis." This paper introduced cone of interior displacements of Dubovickii and Miljutin into economics.

"General equilibrium when Some firms follow special pricing rules", (with Egbert Dierker and W. Neuefeind), Econometrica, 53, 6, 1985 This paper stimulated a subfield of economics, devoted to pricing rules, as discussed by Jacques Drèze: "Starting with a paper in Econometrica by Dierker, Guesnerie and Neuefeind (1985), a theory of general equilibrium has developed for economies with non-convex production sets, where firms follow well-defined pricing rules. In particular, existence theorems of increasing generality cover (to some extent, because of various differences in assumptions) the case of Ramsey-Boiteux pricing. Those interested primarily in applications might express skepticism, perhaps even horrified skepticism, upon realizing that 90 pages of a serious economics journal—a 1988 issue of The Journal of Mathematical Economics—were devoted to existence proofs of equilibrium in non-convex economies, under alternative formulations of the assumption that entails bounded losses at normalized prices. Still, I think that economic research must cover the whole spectrum from concrete applications to that level of abstraction."