Still pursuing roots of the modern “subject” in medieval Latin scholasticism by way of Alain de Libera’s Archéologie du sujet, I’ve reached the point where de Libera reviews Bernard Lonergan’s detailed account of act, action, and related terms in Aquinas. The most noteworthy conclusion is that Aquinas distinguishes “act” from “action” in opposite ways in different texts, when he combines it with his other distinction between cases of immanent and transient action. This confusion appears not to have originated with Aquinas himself, but rather with the Latin translations of Greek texts that he used.
In any event, the way these distinctions are deployed by Aquinas is to say the least highly fluid, which is to say that any attempt to interpret them univocally would result in contradictions. (Burrell, who considers the analogy of being a later development attributable to Cajetan, nonetheless suggests that there is an analogy of action in Aquinas.)
De Libera constructs a table of Latin terms (vol. 3 part 1, p. 325) used by Aquinas for the Greek energeia (literally “in-actness”, for which I’ve been using the conventional translation of “actuality”) in the agent and in an external product, respectively. Energeia may be actus in the agent and actio in the product, or vice versa. It may be operatio in the agent and either actio or factio in the product. It may be actio in the agent and factio in the product.
“What it is necessary to understand in this context is that for Aristotle it is one and the same principle that accounts for act, whether in the agent or the product. That principle is form” (ibid, my translation, emphasis added). According to de Libera, for Aquinas too form is the principle of both the act that remains in the agent, and that which passes to the product. (Burrell reads Aquinas in a relational way that avoids de Libera’s suggestion of something passing between agent and product. The idea of something passing between agent and product suggests Suarez’s later explanation of efficient causation by “influence”.)
De Libera takes note (pp. 327-332) of the Latin translation of the influential definition of praxis (ethical action or practice) in the treatise On the Nature of Man by the 4th century CE Syrian bishop Nemesius of Emesa used by Aquinas. In Greek, Nemesius says “praxis is energeia logiké“. The Latin translation by Burgundio of Pisa says “gestio is actus rationalis“. But the same translator rendered the same Greek sentence in The Orthodox Faith by the 7th century monk John of Damascus as “actio is operatio rationalis“.
This might seem like a complete muddle. But if we take act as form as the guiding thread as de Libera suggests, it may be possible to get something coherent out of it. On the other hand, some adjustment would still be required if we also accepted the identification of act with action and of action with an efficient cause. If act is supposed to be understood as form and end and action as the efficient cause or means by which an end is accomplished, then act cannot be identified with action.
It is one thing to recognize the limits of attempting to apply univocity and formalism in logic to the real world, and quite another to affirm a contradiction. But this is a quite delicate area, and sometimes there are arguments whether there is truly a contradiction or merely an implicit distinction between cases. The answer to this depends on interpretation, and every interpretation is subject to dialogue.
De Libera says that Burgundio’s translation of John of Damascus “introduces nothing less than the ‘modern’ vocabulary of action” (p. 327). Thus it seems that Aquinas ends up with an unstable combination of Aristotelian and “modern” meanings for act and action, but the instability was already present in the sources he used.