Abstract
Cournot's economics was deeply rooted in French mathematics in the nineteenth century. The main stream was Laplace-Lagrange's physico-mathematics. But in examining what drove Cournot to economics, we must not dismiss another stream, that is the tradition of social mathematics. It was probability theory which supported social mathematics as a principal tool of analysis. However, the mathematical machinery which Cournot used in economics was not probability theory but mathematical analysis while he succeeded the tradition of social mathematics. The transformation of mathematical methodology of economics due to Cournot was made possible by his peculiar grasp of the law of large numbers.
