Lately I’ve repeatedly mentioned Thomas Aquinas (1225-1274), and I feel some additional due diligence is in order. Though I have browsed his major works, I am assuredly no Aquinas scholar, so I want to tread carefully. This is an exploration, and conclusions may be revised.
My currently interrupted arc treating Alain de Libera’s Archaeology of the Subject has brought to light some unfamiliar suggestions regarding Aquinas’ role in the formation of the modern concept of action as a central explanatory term. Act, action, and actuality are three distinct things in Aristotle, and they seem to be three different distinct things in Aquinas. We have to be careful that all these distinctions are not confused. So, I am embarking on a little detour to get a clearer sense of what they specifically mean in Aquinas.
The most famous theologian of the Catholic church, Aquinas is a very substantial figure whose work has given rise to diverse interpretations. His principal concern was what is called revealed theology, which properly speaking is outside my scope here, but he was perhaps best known (and initially controversial) for his philosophical theology, and for fusing discourses of theology and philosophy. Without ever losing sight of things he considered to be known by faith, he gave an unprecedented place to philosophical arguments in his theological works, and also developed a highly original purely philosophical theology, which he held to independently point in the same direction as his revealed theology.
Contrary to the myth that the Latin middle ages were dogmatically Aristotelian, the place of Aristotelian learning and the social status of philosophy in Aquinas’ lifetime were actually quite precarious, encountering widespread opposition from religious conservatives. Were it not for the conciliatory work of Aquinas and its eventual acceptance by the Church, conservatives might have succeeded in rolling back the great cultural advances that began in the 12th and 13th centuries with the influx of Arabic, Hebrew, and Greek learning into the hitherto rather barbarous world of Latin-speaking Europe. If I often sound critical of Aquinas and disagree with his extraordinarily original redeployment of some key Aristotelian terms, that should be taken in the context of this larger historical debt.
On the question of the soul, Thomist scholar Ralph McInerny explains in the Stanford Encyclopedia of Philosophy that Aquinas in questions 75 and 76 of the first part of Summa Theologica distinguishes between a substance and a “subsistent”. He also develops a concept of a being’s actus essendi or “act of existence”. Both of these details — which have no precedent in Aristotle — are new to me. This is the same part of Summa Theologica that de Libera was focusing on.
The human soul for Aquinas is not an independent spiritual substance as an angel would be; rather it is the subsistent substantial form and formal principle of an embodied human being. It makes the human what she is, but is not complete in itself. As a principle of a nature, it has no nature of its own, and is not a substance in its own right. Its nature is to be the formal element of a complete (embodied) substance.
According to McInerny, Aquinas stresses that “the soul exists in a living being as the substantial form of an animal”. Socrates as a human has all the vital activities of a living animal. For Aquinas none of these are distinctive activities of the soul itself, because they are involved with bodily functions. On the other hand, the intellect of Socrates is said by Aquinas to be a distinctive activity or “operation” of Socrates’ soul itself that involves no corporeal organ, and this operation is said to be able to exist independent of the body.
Aquinas acknowledges this to be an unnatural state, since the soul is not complete in itself. But he holds that it is enough to establish that the human soul has an operation that does not depend on a bodily organ, in order to show that the human soul is an incorporeal subsistent that can exist independent of the body. Souls of nonhuman animals have no nonbodily operation, and therefore are not immaterial subsistents. At the same time, the intellectual soul of a human is distinguished from an angel precisely because it is the substantial form of an animal.
Taking it as established that Socrates as an embodied human being is not the same as the soul of Socrates, Aquinas according to McInerny argues that Socrates and his soul nonetheless are both “subjects” of one identical activity or operation. Intellect is an activity of Socrates’ soul that is equally an activity of Socrates the complete human. Aquinas holds that for an animal with an intellectual operation, the intellectual soul and the animal (and vegetable) soul are one and the same.
McInerny summarizes, “In the case of other animals it is the animal itself, the living substance, that is the subject of the act of existence, and both soul and body have existence through the substance. Here in the human case, the soul is said to be the subject of the act of existence because it has its own operation.”
Rationality — or acting knowingly and willingly — “is the distinctive form that intelligence takes in human beings as animals. Rationality involves the back and forth of argument moving from one thing known to another, and advancing in knowledge by such movement. Thus, for Thomas, while angels and God can be said to be intelligent, they are not rational.”
“Reason does not distinguish us from animals; it distinguishes us as animals. So according to Aquinas, while it is true that the activities of intellect and will are not the actualities of any physical organs, they are nonetheless the activities of the living human animal. It is Socrates the animal who knows and wills, not his mind interacting with his body.”
If acting knowingly and willingly has the plain ordinary meaning it does in the discussions of responsibility in Aristotle’s Nicomachean Ethics, I could fully subscribe to each individual statement in the last two paragraphs. This has no fancy metaphysical prerequisites. But a premise about acting knowingly and willingly does not seem to me to justify a conclusion about the activities of knowing and willing as such. Nor do I think that knowing and willing is the proper activity of Aristotelian nous or “intellect”.
(I think even Averroes would agree that it is Socrates the animal who “knows and wills”, in the sense that those terms have in Aristotle’s ethics. I think he would like the distinction between intellect and the reason of the rational animal. But I think Averroes would go on to specify that knowing and willing and rationality attach to the animal by way of a development of the animal’s “imagination”. I would myself also emphasize the role of language and ethos.)
I am not sure about calling intellect an operation “of the soul itself”, or indeed an “operation” at all. But I truly have no idea what an “act of existence” would be in Aristotelian terms. Plotinus spoke of the natural act of a being as its good. But “act of existence” to my ear suggests something more like Spinoza’s conatus or effort to exist, which seems at least in part to have a Stoic heritage. Neither of these meanings seems applicable to God. But then, neither is it yet clear to me how the “act of existence” of a created being is related to Aquinas’ notion of the pure act of pure Being, which I have understood as conferring the existence of beings.