[The medical rationale category and a new epistemology in health].

This article is an analytical report on the 20-year trajectory of the 'medical rationale' category that emerged in the early 1990s in the area of Social and Human Sciences in Health in the field of Public Health. Its objective was to study complex and therapeutic medical systems and traditional, complementary and alternative medicines. Based on a critical review of the literature, it presents some aspects of the cultural, political, institutional and social context of its emergence, as well as its main contributions and developments on a theoretical level and on social policies and practices in health. The southern epistemology concept of Boaventura de Sousa Santos is used to reflect upon the contribution of the 'medical rationale' category to the critique of the post-modern scientific rationale and to the creation of a new epistemology in health.