Il concetto di sostanza nelle Categorie e nella Metafisica di Aristotele

This paper examines the concept of substance (ousia) in Aristotle’s Categories and Metaphysics through a critical and comparative analysis of the interpretations proposed by J. L. Ackrill and S. Menn. The study first addresses the longstanding debate concerning the status, function, and philosophical scope of the Categories, questioning whether they should be understood primarily as a logical–dialectical handbook or as an ontologically significant treatise. According to S. Menn, the Categories serve as a dialectical encheiridion, providing methodological tools for classification and argumentation without engaging in causal or metaphysical inquiry. By contrast, J. L. Ackrill maintains that the logical distinctions developed in the Categories reflect the real structure of being and thus constitute an initial sketch of Aristotle’s ontology. The paper then focuses on the notion of substance as articulated in the Categories, especially the distinction between primary and secondary substances and the criteria that establish the priority of primary substances. It highlights how Menn interprets these criteria as purely dialectical rules for classification, while Ackrill reads them as expressing genuine ontological commitments. Finally, the relationship between the Categories and Metaphysics is examined, showing how Aristotle moves from a non-causal, classificatory account of substance to a causal and explanatory investigation of substance in Metaphysics Ζ. The paper argues that, while significant methodological differences exist between the two works, the Metaphysics presupposes and develops the conceptual framework established in the Categories, revealing a fundamental continuity in Aristotle’s philosophical project.