Suppositiones pro istis dubiis solvendis. Futuri contingenti e profezie nel Tractatus de praedestinatione et de praescientia Dei respectu futurorum contingentium di Guglielmo di Ockham

Abstract

In the Tractatus de praedestinatione et de praescientia Dei respectu futurorum contingentium, Wil-liam of Ockham uses the term suppositio – which in the Summa Logicae was the referential property allowing terms to stand in place of the res – as a translation of Aristotle’s ὑπόθεσις. In the Posterior Analytics, a hypothesis is the necessary premise to the scientific reasoning, assumed without demon-stration but later confirmed by the correctness of the conclusions. In the case of future contingents and prophecies, in the Tractatus, suppositiones are both indemonstrable, as they come from an act of belief, and necessary, since they found the possibility of a logical-demonstrative reasoning about objects that present themselves to the grasp of intellect only ficte. Ockham thus applies the method of propositional logic to a theological context, providing scientific status to the knowledge of future contingents. In this framework, the crucial distinction between present-tensed propositions secun-dum rem and secundum vocem is not a merely linguistic ad hoc solution to the problem of future contingents’ and prophecies’, knowability. Rather, the vocaliter nature of future contingents must be understood as a fictio or a suppositio needed to cut short the causal chain connecting the plane of resto that of cognitive acts, in coherence with Ockham’s theological and ontological parsimony.