Gerard Debreu

In 1945 Gerard Debreu married Françoise Bled. They had two daughters, Chantal and Florence, born in August 1946 and February 1950 respectively.

He breathed his last on 31 December 2004 in Paris, France, at the age of 83.

Gerard Debreu was born to Camille Debreu and Fernande Debreu, in Calais, France on 4 July 1921. At an early age his father committed suicide and his mother died of natural causes, which left him as an orphan.

He did most of his schooling in his native town and completed high school prior to the start of the Second World War. After that, he went to Ambert to prepare for his university entrance examinations.

Because of the war, he could not take his final examinations, and instead, had to enlist himself in the French army, after which he was transferred for training to Algeria. Then he served in the occupying French forces in Germany until July 1945.

After the war ended Debreu passed his Agrégation de Mathématiques exams. By this time he had also started developing an interest in economics, particularly in the general equilibrium theory of Leon Walras.

He served as an assistant in ‘The French National Centre for Scientific Research’ from 1946 to 1948. It was during these two and a half years that he made the transition from mathematics to economics.

Gerard Debreu began his career by working as a Research Associate. He joined the Cowles Commission at the University of Chicago in 1950. Though he remained there for five years, he visited Paris from time to time.

Debreu had to devote all of his time and focus on his research, as the Cowles Commission was beyond all his expectations and provided him with a rich intellectual atmosphere. Debates, discussions, and research on mathematical economics helped him progress in his work on Pareto Optima, on utility, as well as on his research on the existence of a general economic equilibrium.

Together with economist, writer, and political theorist Kenneth Arrow, he published a paper ‘Existence of Equilibrium for a Competitive Economy’ in 1954. In this work they managed to prove the existence of a general equilibrium, using topological rather than Calculus based methods.

He published a classic monograph ‘Theory of Value: An Axiomatic Analysis of Economic Equilibrium’, which was published in 1959. Here, he provided the mathematical underpinnings for the phenomenon of equilibrium in supply and demand that was first articulated by Adam Smith almost two centuries ago, in 1776. Debreu managed to develop methods by which to analyze factors influencing equilibrium.

In 1960-61, he worked at the Center for Advanced Study in the Behavioral Sciences at Stanford. Here, Debreu spent most of his time researching for the proof of a general theorem on the existence of an economic equilibrium.

His first work was ‘Existence of an Equilibrium for a Competitive Economy’, which he wrote together with Kenneth Arrow. It was Leon Walras, who had first formulated the state of the economic system at any point of time as the solution of a system of simultaneous equations that represent the demand for goods by consumers, along with the supply of goods by producers, along with the equilibrium condition that supply equal demand on each market. But Walras couldn’t give any conclusive arguments to prove his theory, according to which, every consumer acted so as to maximize their utility and each producer acted so as to maximize their profit. However, Gerard Debreu and Kenneth Arrow were able to prove the theory in this work, using calculus-based methods.

Theory of Value: An Axiomatic Analysis of Economic Equilibrium’, which Gerard Debreu published in 1959, is regarded as one of the most important works in mathematical economics. In this work, the mathematical underpinnings for the phenomenon of equilibrium in the theory of supply and demand are provided and explained. It was first articulated by Adam Smith in 1776. Its logical consistency is proved and its efficiency properties are investigated as well.

Mathematical Economics: Twenty Papers of Gerard Debreu’ was published in 1986. The twenty papers related to mathematical economics in this work were selected by the author himself. This book also has a brief introduction by German economist and mathematician, Werner Hildenbrand, who not only assesses Professor Debreu's contribution to economic theory but also explains the important part these papers played in the development of the subject.

Landmark Papers in General Equilibrium Theory, Social Choice and Welfare’ was another one of Debreu’s and Arrow’s most important works, which was published in 2001. Here, those papers, which in their views have made the most important contributions, are collected, for the benefit of students and researchers of economics.