Turning Potentialities into Possibilities: Early Medieval Approaches to the Metaphysics of Modality

Early medieval reflections on modalities are deeply indebted to the modal theories developed by Aristotle in his De Interpretatione, to which scholars were acquainted through the mediation of Boethius’ translations and commentaries. Although Aristotle’s modal system was considerably enriched in the early Middle Ages with a more sophisticated syntax and a more expressive logic, the general framework in which modal language was analyzed remained essentially Aristotelian in spirit. However, Aristotle’s modal views were also loaded with metaphysical assumptions that some early medieval authors felt uncomfortable carrying along. This metaphysical background was connected to the Aristotelian interpretation of possibilities as ontologically grounded in the potencies or potentialities of things, that is in the powers, tendencies or capacities that certain substances have of being otherwise than they actually are (See e.g. Simo Knuuttila, Modalities in Medieval Philosophy, London, 2003, New York: Routledge, pp. 19–31; 46–48). The potency-based account of possibility, further reinforced by Boethius in his commentaries, was questioned by some logicians in the early twelfth century. These authors were driven by a special interest in unactualized possibilities and in the modalities of non-things, an interest that ultimately led them to detect a number of problems related to the Aristotelian modal paradigm. In opposition to it, they developed a modal theory according to which the term “possible” has no such ontological correlate, and does not denote any modal property or intrinsic feature possessed by substances.