Résumé
This article reconstructs Jacques Rueff's discourse on method. After demonstrating that "all sciences [including moral sciences] are rational" (Rueff, 1922, 4), Rueff argues that the "scientific" method of physical sciences applies in "moral sciences". He therefore considers that all sciences have a common methodology and he disagrees with traditional conceptions which distinguish visions and methods by the type of sciences.
However, what is meant by "scientific" deserves to be specified. Furthermore, the idea of a single methodology between physical and moral sciences can be considered only by revealing commonalities between them. To illustrate moral sciences, Rueff takes political economy as an example. Applied to economics, his method implies the development of statistics, which allows implementing the functions attributed to this method while strengthening the rational and empirical characters of this science. Indeed, whereas "the dispute of methods" pitted rationalism against empiricism, Rueff tries to reconcile both. Considering "moral sciences can improve only by staying in touch of real world" (Rueff, 1969, 66), Rueff's priority is to put the theoretical and empirical dimensions of sciences on equals terms.