This article argues that historical epistemology offers the history of philosophy and science more than a mere tool to write the history of concepts. It does this, first of all, by rereading historical epistemology through Michel Foucault's “techniques of the self.” Second, it turns to the work of Léon Brunschvicg and Gaston Bachelard. In their work we see a proposal for what the subjectivity of scientists and philosophers should be. The article thus argues that their work is driven by a (...) normative psychology: a set of prescriptions for which mental constitution a scholarly self has to have. In the Conclusion, it returns to existing analyses of “open‐mindedness” as a virtue and explores in what way these cases challenge these analyses, as well as to what extent Foucault's “techniques of the self” can be applied to other cases in the history of French philosophy. (shrink)