FROM OPPOSITION TO COMPLEMENTARITY: EPISTEMOLOGICAL CRITERIA FOR THE CHOICE AND INTEGRATION OF QUALITATIVE AND QUANTITATIVE METHODS

Abstract

This theoretical essay examines the epistemological foundations of the opposition between qualitative and quantitative approaches in the human, social, and health sciences, emphasizing the conditions that legitimize their integration. It starts from the observation that the diagnosis of the artificiality of this dichotomy has been established in the international literature since the late 1980s and was formulated in Brazil by Minayo MCS and Sanches O (1993), without significantly changing research practice. It argues that this persistence results from the absence of decision-making criteria capable of translating the epistemological debate into concrete research design choices. The study reconstructs the genealogy of the dilemma, from the nineteenth-century controversy over method and the paradigm conflicts, distinguishes paradigm, method, technique, and research design, and adopts critical realism as the meta-theoretical position that legitimizes integration. As its main contribution, it proposes operational epistemological criteria organized into four decision-making stages, with a precedence rule and an application flowchart. Unlike existing instruments, which guide integration and assess its quality, the proposed framework operates prior to the methodological decision and acknowledges that, in certain cases, the correct choice is not to integrate. The criteria are demonstrated through two cases, including the essay itself. It concludes that the opposition is sustained only when incommensurable ontological referents are explicitly assumed and that, outside this restricted situation, the central issue should be the quality of inference.