Per Caritatem

Wolters notes that Scotus (in his initial questions on book IX of the Metaphysics) clarifies a number of ambiguities with regard to act and potency.  As Wolter points out, concerning potency, Scotus makes the important distinction between “potency as principle and potency as a mode of being” (Wolter: 167).  Here Scotus takes principle as a sort of cause-viz., an efficient or material cause-or originative source.  Passive potency is correlated with matter broadly speaking, and active potency with some kind of efficiency.  With a number of other scholastics, Scotus expands the “notion of an active potency or principle beyond that of an agent that imparts motion to include that which gives being or existence as such to its effect” (Ibid., p. 167).  Though Scotus makes further distinctions (he is the subtle doctor after all), for our purposes the following rough sketch suffices to describe an active potency, viz., that which gives existence to something (Ibid., p. 168).  Wolter then adds that describing an active potency in this way has the added bonus of

stressing that cause is cotemporal with its effect, and that the causal action is a continuous creative and sustaining productivity, as opposed to the Humean notion that views all causality as a necessary temporal relationship between an antecedent and a subsequent event. Scotus needs this type of relationship if he is to clarify how the will as an active potency can create or elicit an action of volition or nolition, or how it can not only initiate but sustain a voluntary action such as singing or walking (p. 168). 

Here I take Wolter to be pointing out the insufficiency of a mechanistic or external view of causality with regard to free will as understood by Scotus.  For Scotus the will is self-determined (not externally determined) and at every instant (hence,Wolter’s stress on causal action as “continous creative and sustaining productivity”) has a potency to do its opposite and can refrain from acting.  However, with regard to Hume’s view, my understanding is that since he considers causality, necessity etc. to be supplied by the mind via habit or custom, free will is in a sense guaranteed because we as free agents are not part of the (supposed) causal nexus.  If I understand Hume correctly, then am I correct to see Wolter’s main point to be contrasting a mechanistic view of causality with Scotus’ understanding of the will as self-determined (and hence, by definition not externally caused)-if so, what am I missing with regard to Hume’s view to make everything that I have said above harmonize?

*A. Wolter, “Duns Scotus on the Will as Rational Potency,” as found in The Philosophical Theology of John Duns Scotus. (Ithaca:  Cornell Univ. Press, 1990), pp. 163-180.