Aquinas on the Act of Thought

In a few very dense pages, Alain de Libera summarizes a number of key theses extracted from the works of Thomas Aquinas pertaining to the act of thought (see also “The Subject” In Medieval Times; Origins of a Subject-Agent). According to de Libera, these principles — which represented a significant departure from Augustine’s insistence that the human soul should not be viewed as a “subject” in the sense of something standing under something else — attained a wide currency in Latin scholasticism. They laid the groundwork for the modern notion of “the subject” as active mind and ego.

“Thought is an action (actio) or an operation (operatio) called ‘intellectual’ (intellectualis) or ‘intelligible’ (intelligibilis) because it is the deed of intellect and treats of the intelligible, and unites these two dimensions in its proper actuality. Intellectual has two senses: subjective and causal. Contemplation, also called theoretical thought, the knowledge of the intelligible, is intellectual because it takes place in the intellect itself, which is to say that, relative to the body, it is atopical or utopical [without place], because the intellect itself is not located in the body; the other actions called intellectual are so in a causal sense; they are called such because they are directed or imposed, that is to say commanded, by the intellect and executed by means of a bodily instrument — with respect to which, in distinction from the act of thought — they are localizable and localized: this is the case, for example, with walking and riding, two actions called imposed.”

“…There are two kinds of actions: one remains internal to the agent, begins and ends in it (it is called: manens [remaining] or consistens [consisting] or quiescens in agente [resting in the agent]); the other is exercised on another thing or an exterior matter (it is called: exiens [coming out] or progrediens [moving forward] or tendens [tending] or transiens in alterum [passing into another] or in materiam exteriorem [into the matter of exteriors]). This duality prolongs the Aristotelian distinction between immanent action and transitive action…. The distinction, massively utilized to theorize the difference between the psychic (where immanent causality reigns) and the physical (where the transitive reigns), is also applied within the physical sphere, notably to light….”

“…Only that which is in act acts (Nihil agit nisi secundum quod est actu). This fundamental thesis, which lays the foundation of the articulation between actio and actus [action and act], introduces itself in diverse other formulations, such as: Omne agens agit, inquantum actu est [every agent acts, insofar as it actually is], or Unumquodque agit secundum quod est actu [each one acts according to what it actually is]. We will call it ‘the principle of the actuality of the agent’.”

“Numerous principles arise from this or assume its validity. This is the case with [the principle that] that by which something first operates is the form of the operator; the principle of the subjection of action in the power of the agent… and the subjective principle of action [actions belong to something standing under them]” (Archéologie du sujet vol. 3 part 1, pp. 53-56, my translation). De Libera goes on to mention additional principles such as “attribution of action to the principal agent” (pp. 56-57); “action is a function of the being of the agent” (p. 57); “determination of action by the nature of the agent” (ibid); “determination of action by act” (ibid); and “actuality is a determination of the act of an agent” (ibid).

The bottom line of all of this seems to be that thought is the action of an agent. Neither Aristotle nor Augustine treated thought in this way or had this kind of view of action and agency, but a long medieval and modern heritage makes it seem like common sense to many people. Aristotle spoke of intellect as coming to us “from outside”. He was certainly very interested in practical doings, in process, and in being-at-work, but did not reduce these to the discrete “actions” of discrete “agents”. Activity, I want to say, is something different and broader than this. (See also Not Power and Action; Aristotelian Actualization; Aristotelian Subjectivity Revisited).

Suarez on Agents and Action

Among the greatest of the Latin scholastics, Francisco Suárez (1548-1617) was a profoundly original and highly sophisticated theologian-philosopher who significantly influenced early modern thought, and also produced monumental summaries of several centuries of Latin scholastic argument. A full third of his gigantic Metaphysical Disputations was devoted to an extremely detailed and systematic discussion of causality. A large volume entirely dedicated to efficient causes has been translated to English, and a web search popped up several secondary discussions. My comments here will be very high-level, mostly based on those.

In this scholastic context, traditional Aristotelian terms like cause, being, and substance are all given very different explanations from the nonstandard but hopefully both more historical and more useful ones I have been giving them. Latin scholastics tended to have a somewhat neoplatonizing, substantialized notion of Aristotelian causes. A common view was that any cause must be a substantial entity of some sort, whereas causes in the common modern sense are events, and I read Aristotle himself as identifying causes with “reasons why”.

Suárez held to the view of causes as substantial entities, and apparently went on to argue that all causes give Thomistic being (esse) either to a substance or to an accident in a substance. This influx or “influence” is described as a kind of immaterial flowing of being that makes or produces, without diminishing the agent. In the case of an efficient cause, this influence occurs through action, and the substantial efficient cause is called an agent. (By contrast, in the above-linked article, which has brief additional remarks on Suárez, I quoted Aristotle saying in effect that an agent’s action is more properly an efficient cause than the agent, and that something like a technique used in an action is more properly an efficient cause than the action.)

Suárez’s metaphysical emphasis on actions producing being in things has been characterized as transitional to a modern, event-based view of causality. While Suárez himself held to the idea that causes were substantial agents, early modern mechanism indeed seems to have kept his emphasis on action but moved to an event-based view.

It seems to me to have been a historical accident that mathematical natural science arose on the basis of an event-based view. While mathematics certainly can be used to develop precise descriptions of events, any mathematical analysis relevant to this can also be construed as a “reason why” rather than a mere description. On the frontier of analytic philosophy, Brandom is again suggesting that a consideration of reasons actually circumscribes — and is necessary to underwrite — consideration of events and descriptions. This suggests a new motivation for recovering Aristotle’s original reason-based view.