French Engineers and the Machinery of Society: X-Crise and the Development of the first Macroeconomic Models in the Nineteen Thirties

The purpose of this article is to highlight the originality of X-Crise, an Ecole Polytechnique association formed in nineteen thirties' France. Firstly il analyses the factors leading the French engineers to look collectively, for the first time of their history, at the big politicoeconomic problems of their epoch. Two factors seem particularly relevant on this matter : their epistemology and value system on one hand, and their perception of the theoretical and political impotence at that time on the other hand.Secondly this paper presents the main original theoretical elements that arose from the group's deliberations. Among them, it exposes the Guillaume brothers' macroeconomic model [1932], one of the very first macroeconomic model produced in France, and Potron's first application to economics of Perron-Frobenius's theorem (Potron [1911] and [1935]).