Piero Mattei-Gentili

La costumbre no es una reliquia ni una fuente menor que los sistemas contemporáneos hayan superado. Es, por el contrario, el suelo sobre el que todo derecho se asienta: aquello que lo constituye, lo sostiene y explica su identidad y su cambio a lo largo del tiempo. Este libro defiende esa tesis desde la filosofía analítica del derecho mediante tres movimientos articulados. El primero muestra cómo las normas consuetudinarias operan al interior de los sistemas jurídicos y por qué las normas últimas de cualquier sistema —aquellas que no pueden derivarse de ninguna otra— son necesariamente de naturaleza consuetudinaria. El segundo ofrece una teoría convencionalista de los fundamentos normativos del derecho, capaz de explicar tanto ese fundamento como el cambio jurídico no intencional que opera silenciosamente más allá de los textos. El tercero somete esta teoría a prueba en el terreno donde la costumbre resulta más visible y problemática: el razonamiento de jueces y abogados, y el derecho internacional. El resultado es un argumento a favor de tomarse la costumbre en serio —y con ella, el convencionalismo— como clave de bóveda de la teoría jurídica contemporánea.

This article addresses the epistemological and conceptual challenges involved in proving customary norms in international law. It argues that confusion surrounding usus and opinio jurisstems from a failure to distinguish between the ontology of customary norms and the determina-tion of their existence. Drawing on legal epistemology, social norm theory, and analytical legal phi-losophy, the article conceptualizes customary norms as products of socially constituted structures grounded in shared normative expectations. Proving opinio juris does not require showing that States regard their conduct as legally mandatory, but rather that second-order normative expecta-tions are manifested through patterns of practice. The article defends a dual inferential model — inductive reasoning to establish usus, complemented by abductive reasoning to infer opinio juris— and proposes a narrative coherence test as a qualitative supplement to the preponderance standard.

Este trabajo ha sido concebido como un homenaje para Rolando Tamayo y Salmorán por medio del examen de algunas de sus principales aportaciones a la filosofía del derecho. Con esto en mente, el texto parte de un planteamiento panorámico sobre el estado de la filosofía jurídica en México y el ambiente en el que se desarrolla Tamayo. Con posterioridad, se explica que el ensayo estará enfocado en explorar dos aspectos de su obra. Primero, la importancia de conocer el origen de la ciencia del derecho, la jurisprudentia, de la formación de sus conceptos, sus fundamentos romanos y los postulados epistémicos que tomaron de los griegos. Segundo, la definición del derecho como una técnica de reforzamiento de la conducta que es posible encontrar en todas las sociedades. De modo tangencial se explica el concepto de norma como herramienta primordial de la técnica jurídica.

This essay defends that Alchourrón and Bulygin were not mistaken in adopting the semantic (hyletic) conception of norms and in asserting that it is consistent with positivist legal theory. However, it is true that they do not provide arguments about how the semantic conception is related to the positivist thesis of the social facts. Therefore, this paper seeks to expose the reasons why the rival conceptions are not satisfactory, and, in addition, conventionalism is proposed as a means of explaining how it is possible to adopt the semantic conception in a manner consistent with an anti-realist ontology concordant with the social facts thesis.

The essay addresses the debates about the ontology of norms considering the case of accounting for customary norms. It undertakes and defends a stance in favor of a semantic ontology by developing a framework for the explanation of norms as abstract objects and their linking with social facts to be identified in categories like “customary”, “enacted”, “legal”, “grammatical”, and so on. Furthermore, the work addresses the rival conceptions (pragmatic and eclectic) by showing the specific impossibility that these face for giving a satisfactory account on customary norms. The inquiry concludes by exploring some possible insights from the philosophy of mind to explain the conceptual nature of norms as mental representations.

The present essay addresses the conceptual structure of customary law, understood as a set of customary rules. More specifically, it deals with the core question of what opinio juris entails as a constituent element of customary law. The work will begin with an analysis of samples of common strategies in contemporary legal theory that deal with opinio juris when analyzing the structure of customary law. Subsequently, following Hart’s notion about what constitutes social rules, and introducing explanatory features from Game Theory applied to social philosophy and some insights from Behavioral Economics, the goal of the present study is to propose a different conceptual path for analyzing and identifying customary law with what could be understood as “opinio juris”, given the conceptual necessity of finding the normative element that lies within the usus, or social practices.