Sine qua non causality and the context of Durand’s early theory of cognition

This paper explores the origins of the term "causa sine qua non" used by Durand de Saint-Pourçain to describe the role of material things in knowledge. I show that its technical meaning comes from the Stoics and was transmitted to the Middle Ages by Boethius' commentary on Cicero's Topics. The expression "sine qua non" here does not have the ordinary and restricted meaning of "indispensable", "necessary condition", which can also apply to direct, per se causes of an effect. In the present context, sine qua non causes do not act on the effect in question, either as concomitant, secondary, or instrumental causes, or as remote causes. They act only on that which hinders the actualization of a potentiality, in order to remove that obstacle. For example, the removal of a support that prevented something from falling does not act on that thing, nor does it add anything to its tendency to fall; it simply enables that thing to exercise its own actualization. Similarly, in cognitive processes, external things do not impose anything on the soul, but simply give it the opportunity to actualize its faculties of its own accord. I situate Durand's use of this form of causality in the context of late 13th/early 14th century theories of cognition, among several other attempts to find an alternative theory to the standard Aristotelian model and to maintain the pure activity of the soul with respect to the body.