AGENT

A transliteration of the scholastic Latin agens, in general having the same meaning as mover (movens ), efficient cause, or simply cause. St. thomas aquinas regularly uses agent and efficient cause indiscriminately, often combining them as causa agens or causa movens. In dependence on Aristotle, he defines an agent as "that whereby a change or state of rest is first produced" (a quo est principium motus vel quietis—In 2 phys. 5.5). In this St. Thomas differs in no significant respect from the general scholastic tradition. At least the older scholastic tradition is also in agreement that agents in the physical order are denominated such from the effect produced by their action in the "patient," or recipient (see action and passion).

Other aspects of the scholastic notion of agent can be seen in the various assertions commonly accepted with respect to agents: "Every agent acts for an end." "Every agent acts insofar as it is in act, and according to its form." "An agent, precisely as such, is more noble than its patient or effect." "Every agent produces an effect similar to itself." "Agent and patient must exist together," and "every physical agent acts by contact" (see scholastic terms and axioms).

The principal kinds of agent recognized by the scholastics include: (1) The perfecting (perficiens ), counseling (consilians ), and disposing agents—the last being subdivided into primary (praeparans ) and secondary (adjuvans ). (2) Equivocal (or analogical) and univocal agents, depending on whether or not the agent is on the same metaphysical level as the patient; this distinction is closely related to that between universal and particular agents and that between incorporeal and corporeal agents. (3) Principal or instrumental and primary or secondary (sometimes "first" and "second") agents. (4) Natural and nonnatural agents, the latter including many other types, such as violent, chance, artificial, and voluntary; a related distinction contains necessary, chance, and free agents. (5) Finally, agents that are causes of being or causes merely of becoming, according as the effect continues to depend on the cause after it is produced or not.

Intellectual agents are included in this list, especially under artificial and voluntary nonnatural agents, but the "agent intellect" (intellectus agens ) is not. The latter is the intellectual faculty rendering abstract knowledge possible, and it is treated under intellect.

See Also: causality; efficient causality.

Bibliography: r. j. deferrari et al., A Lexicon of St. Thomas Aquinas (Washington 1948–53). l. schÜtz, Thomas-Lexikon (New York 1957).

[p. r. durbin]