AN ANALYSIS OF THE RATIO DECIDENDI IN BRAZILIAN LAW: THE ROLE OF ARGUMENTATION IN THE SYSTEM OF JUDICIAL PRECEDENTS

Abstract

This article analyzes the construction and application of the ratio decidendi in Brazilian law, focusing on its role in the formation of precedents and in well-structured legal argumentation. Epistemic (factual) rationality is differentiated from normative (legal and axiological) rationality in legal reasoning, highlighting its importance in sound judgments. The text explores how the weighing of fundamental rights and the principle of proportionality instrumentalize the creation of ad hoc weighting norms, which, when reiterated, become precedents. Methods for identifying and applying precedents in the national scenario are also examined, with emphasis on the provisions of the CPC/2015 (articles 926 and 927). In this sense, it was emphasized that the success of a decision as a precedent depends on the clear identification of its determining basis (ratio decidendi). The article contributes in practice, guiding the various procedural actors in the formation and use of precedents, and theoretically, reinforcing the importance of a rigorous, dialogical legal argumentation committed to the integrity of the legal system. It seeks to contribute to a more structured debate on the future of Brazilian law, reconciling legal certainty, practical rationality and sensitivity to new social demands.