Starting with a distinction of two types of discourse analysis-the analysis of a discourse and discursive analysis-the article discusses an analytical genealogy of truth and knowledge production, that can fulfill both empirical and archival requirements. The model's main purpose lies in understanding diagnostic and therapeutic decision-making in doctor-patient interactions. Historically, diagnostic and therapeutic discourses, in particular in "experimental medicine and medical theory", used to be part of natural philosophy in the 18th and 19th century in the form of dietetics, respectively, psychosomatic medicine and medical semiotics, as well as proto-semiotic philosophy and proto-pragmatism did belong to the same discourses. Subsequently, pragmatic and semiotic social sciences should be enabled to invoke this conceptual legacy to build a bridge between contemporary medical practice and semiotic theories. In discussing the genealogical model in light of the discourse of Norbert Wiley and Margaret Archer, it will be made clear that the model, combined with a deeper understanding of the history of ideas, and a combination of archival and empirical attitude in research, is an effective tool for sociologists of knowledge and medicine.