From his earliest publications, Cournot broke from tradition with his predecessors in applying mathematical modelling to the social sphere. Consequently, he was the first to affirm the mathematization of social phenomena as an essential principle. The fecundity of Cournot’s works stems not only from this departure, but also from a richness that irrigated the social sciences of the twentieth century. In this collection, the contributors – including two Nobel laureates in economics – highlight Cournot’s profound innovativeness and continued relevance in the areas of industrial economics, mathematical economics, market competition, game theory and epistemology of probability and statistics. Each of the seven authors reminds us of the force and modernity of Cournot’s thought as a mathematician, historian of the sciences, philosopher and, not least, as an economist.