SUBSTANTIAM REI MUTARE. FISICA ARISTOTELICA ED AZIONE MIRACOLOSA NELLA FONDAMENTAZIONE DUECENTESCA DELLA PLENITUDO POTESTATIS

The goal of the thesis is to investigate the thirteenth-century origins of the concept of "plenitudo potestatis" (plenitude of power) by utilising the tools provided by political theology and adopting a legal-ontological perspective. Following this path, after an introduction that outlines some concepts employed in the research, the first topic examined is the medieval reception of Aristotle's physical texts, analysing the parallels between the teaching prohibitions imposed on these texts and those affecting Roman law. Building on this ground, the analysis explores the potential influence of these new conceptual frameworks on the development of the notion of "miracle" within scholastic thought. Additionally, it examines how this understanding of divine action aligns with the dichotomy between ordained ("ordinata") and absolute power of God ("absoluta potentia Dei"), particularly as seen in the thoughts of Thomas Aquinas. With the philosophical and theological framework established, the thesis then delves into the evolution of the concept of "plenitudo potestatis", aiming to determine how it became associated with the idea of absolute divine power in the mid-thirteenth century. In the final section, the thesis focuses on the most significant claim tied to "plenitudo potestatis", namely, the Pontiff's power to "change the substance of a thing" ("substantiam rei mutare"). By studying thirteenth-century doctrine, the thesis ultimately reconstructs how these assertions of power were resolved through the interpretive faculties of power and the application of the "canonical" fiction of law ("fictio iuris").