Personalist polymath Arnaud Dandieu (1897-1933) and Bourbaki group mathematician Claude Chevalley (1906-1984) jointly analysed the creative act of extracting from a subject’s lived experience the artificial generality of scientific language. Their collaboration was an early instance of French phenomenology, along with Eugène Minkowski’s psychopathology, which they drew on in taking the scientist rather than science as their first object, and articulating the respective domains of a phenomenology of concrete experience and scientific activity, which abstracts from it both the lesser concrete of measurement and the axioms of higher mathematics. They thus appear as forerunners of a recent phenomenological approach to quantum mechanics, known as QBism, which resorts to a Bayesian statistical anticipation of betting results, as a kind of ‘personalist’ learning curve, to dispel epistemological paradoxes, by shifting the focus from a third-person experimental investigation of ‘outer’ states to a first-person focus on the scientist within whose experience they co-emerge.