Medicine is struggling with the constantly rising incidence of breast cancer. The key in this fight is to be able to speed up diagnosis, as rapid diagnosis reduces the number of aggressive or advanced cases. For this process to be effective, it is necessary to have the right attitude towards diagnosis as a research practice. Our critical analysis of diagnosis, as a methodology of medical science, reflects on it as a research practice that is regulated in a socio-subjective way by a methodological culture. This position allows us to contrast critical methodological culture with the habitual-practical, or methodical, culture of practising diagnosis. We point to the interpretative status of medical analyses performed by medical historians by referring to Italian Renaissance painting and historical-artistic interpretations. In this field, analysing disputes between researchers as a clash of methodologies in the ways interpretation transforms signs into meanings, is a critical methodological reflection. Medicine is a diverse scientific discourse with a paradigmatic structure in which new ways of conducting diagnostic tests may appear. It is only possible to see this from the methodological level. In addition, passive respect for existing patterns of conduct hinders an exchange of views between researchers, what limits the possibility of correcting research procedures. The ultimate consequence of such passivity is an inabili/ty to improve diagnosis, which in turn, harms the interests of patients. In this regard, it is worth remembering that the paramount objective of diagnosis is not the disease, but the patient.