Chapter IV -- 4
St Thomas then asserts that the human soul is both incorporeal and subsistent. As
Therefore, this intellectual principle called mind [Latin: mens; = Greek: nous] or intellect [Latin: intellectus; = Greek: dianoia] has an operation by itself which it does not share with the body. Now, nothing can operate by itself unless it subsists by itself. For, to operate is only characteristic of being in act, and, consequently, a thing operates in the same manner that it exists. For this reason, we do not say that heat heats but that a hot thing does. The conclusion remains, then, that the human soul which we call intellect or mind is something incorporeal and subsistent.
This means that the soul is intelligible, on the one hand, and, on the other hand, that its existence does not depend on any other created object: it exists in and of itself. The significance of this can be taken from the fact that this is, in St Thomas’ philosophy, a necessary precondition for the soul to survive death.
St Thomas remarks that, to speak rigorously, it is the man composed of body and soul who understands by means of the soul, even though we say, loosely, that the soul understands.
St Thomas then denies that the souls of irrational animals are subsistent. That is, the soul of an irrational animal cannot survive the dissolution of the matter of the animal’s body.
So far, St Thomas has said nothing different from what St Macrina has said, except, perhaps, for the notion that the man composed of body and soul understands, not the soul alone.
As we noted above, St Thomas considers the human soul to be subsistent. This means, for St Thomas, that when a man dies, his soul continues to exist. As we have seen, this is connected in St Thomas’ thought not only to the data of Christian revelation, which he is surely following on the matter, but also to the doctrine that the intellectual part of the human soul functions without the use of the body even when the man is alive: the intellectual functions of the human soul are utterly free of the body, although, as we shall see, the intellect makes use of ‘sense data’ from the lower, animal part of the soul, which functions in and through the body. If the intellectual part of the soul, in St Thomas reasoning, were dependent on the body in the same way that the vegetative soul of a plant is dependent on the body of the plant or the animal soul of an animal is dependent on the body of the animal, then the intellectual part of the soul would surely perish on the death of the person.
We would now like to clarify a certain point. St Thomas Aquinas takes the position that the intellectual part of the human soul, which we will describe in detail later, operates without the body. That is, humans reason without the aid of the body, although they reason, according to St Thomas, on the basis of sense-perceptions which necessarily come to them by means of their bodily sense organs. St Thomas is quite clear on this: the intellectual functions occur without the aid of the body, but the sensitive (the perceptual and other animal) functions that humans share with the animals depend on the body, as, indeed, the vegetative functions that men share with the plants.
This is a position of Aristotle. The doctrine of the independence of the mind (nous) from the body can be found in On the Soul III, 4. The doctrine that the mind (nous) survives the body is found in remarks, undeveloped by Aristotle, that are scattered throughout On the Soul. In its final form, where only the active mind (nous) is immortal and eternal, whereas the passive mind (nous) is corruptible, this doctrine is found in On the Soul III, 5.
St Thomas goes so far as willingly to remark that a certain function of the sensitive or animal soul in man related to perceptual judgement (the ‘particular reason’) is said by the doctors of his time to be a function of the mid-part of the head. This is quite shrewd, for that part of the brain does exercise perceptual judgement. However, the question arises: since we now know—to the extent that we know anything—that the brain is implicated in reasoning, how can St Thomas assert that the intellectual part of the soul is completely independent of the body? For the assertion enters strongly into his argumentation for the subsistent nature of the human soul and thence for the survival of that soul outside the body after death.
This is how Fr Copleston addresses the matter:
It is clear, therefore, that the crucial point in Aquinas’ argument in favour of immortality [of the human soul] is his argument in favour of the incorporeality or spirituality of the soul. For if it is spiritual in the sense that its existence is not tied to the existence of the bodily organism or to any corporeal organ, its persistence after death seems to follow.…
Aquinas’ argument in favour of the human soul’s spiritual character is based, as we have seen, on the contention that man exercises psychical activities which are not intrinsically dependent on a corporeal organ. He then argues that this fact shows that the ‘form’ which exercises these activities is itself spiritual. His position would not involve him in denying that intellectual activity has a physical aspect, in the sense that it is accompanied by movements in the brain. It would, however, commit him to denying not only that intellectual activity can be identified with movements of the brain but also that it is intrinsically dependent on these movements, in the sense that there cannot be intellectual activity of any kind without them. In other words, he is committed to denying not only the outdated form of materialism which is represented by Hobbe’s idea that thought is a motion in the head or by Cabanis’ dictum that the brain secretes thought as the liver secretes bile, but also the doctrine of epiphenomenalism according to which the mind, though not a corporeal thing, supervenes when the brain has reached a certain degree of development in the evolutionary process and cannot exist apart from it. He is also committed, of course, to denying the validity of the analysis according to which the word ‘mind’ is no more than a collective name for psychical events. But by denying the truth of such views, Aquinas would deny the truth of the interpretations of the empirical data, not the empirical data themselves. For example, it is doubtless true that intellectual activities [in the embryo, fœtus, etc.] are found only when a corporeal organ has attained a certain degree of development. But to say that mind is a kind of epiphenomenon or efflorescence of the brain is to enunciate a theory about the facts, an interpretation of the facts, the meaning of which is by no means altogether clear and which is in any case open to dispute. Again, the statement that ‘mind’ is no more than a collective term for psychical events expresses a theory or interpretation, the validity of which is open to question. True, Aquinas’ account of the nature of the soul also involves interpretation and theory; for on his own admission we have no direct intuition of the soul as a spiritual ‘substance’. But my point is simply that his interpretation cannot be ruled out simply because it is an interpretation. The question is which is the most adequate interpretation.…
Let us make some remarks here. We are not experts on St Thomas Aquinas. However, it seems to us from reading the relevant passages of the Summa that Fr Copleston is minimizing the radical nature of St Thomas’ assertion that the intellectual part of the soul does not depend (essentially) on the body. True, there might, in Aristotelian categories of thought, be an accidental concomitance of brain function with the operations of the intellectual part of the soul without any damage being done to St Thomas’ position, but, it seems to us, they would have to remain accidental for St Thomas’ position to be valid. Fr Copleston, it seems to us, is minimizing this ‘essential – accidental’ distinction when he says: ‘His position would not involve him in denying that intellectual activity has a physical aspect, in the sense that it is accompanied by movements in the brain.’ It seems to us that this is one area in which the Thomist needs to consider the data of modern science.
Next, the reader may recall our brief discussion in Chapter I of Le hasard et la nécessité, written by the Nobel laureate, Jacques Monod. There we remarked that Monod taught a doctrine of epiphenomenalism with regard to the nature of the human mind. Here we see a clear description of that doctrine, one which agrees quite closely with Monod’s own doctrine of the development in evolution of the mind of man.
To continue with St Thomas, St Thomas next asserts, quoting St Augustine, that a man is not merely his soul but his body and soul taken together. This is also a position of St Gregory of Nyssa, as we saw in Chapter III, above, in discussing St Gregory’s remarks in On the Making of Man concerning the conception of each individual man. However, St Thomas takes the unity of body and soul much further than St Augustine or St Gregory.
It might be remarked, moreover, that St Thomas insists on the unity of body and soul on account of his Aristotelian metaphysic. For we see that
It is sometimes taught in Orthodoxy, for example among Elders with clairvoyance and in the Spiritual Homilies of St Makarios, that the soul has the same appearance as the body of the person whose soul it is.
St Thomas goes on to say that only if the intellectual part of the soul were immaterial could it cognize the intelligible nature or essence of, say, a stone, something it manifestly can do.
St Thomas addresses the difference between animals and men. He remarks that as concerns their bodies, both animals and men are taken from ‘the dust of the earth’ (Gen. 2, 7). However, the soul of the animal is but the result of a certain ‘corporeal virtue’, whereas the soul of man is ‘from God’. In support of this distinction, St Thomas adduces the passage, Gen. 1, 24, ‘Let the earth bring forth [every] living soul,’ as referring to the animals, and the passage, Gen. 2, 7, ‘He blew into his face a breath of life,’ as referring to man. It should be noted that St Thomas later states clearly that the soul of man is created and not of the same substance as God.
St Thomas remarks that when the soul is out of the body (after death), then it possesses an angel-like mode of comprehension.
St Thomas goes on to say that the human soul is incorruptible. This is an Augustinian position.
However, he denies that the soul and the angel are of the same species. In ordinary language, this means that there is an essential difference between the human soul and the angel.
This is clearly of great importance to us in the theory of asceticism, for the program of Evagrius Pontikos and, following him, St Hesychios, and indeed the Egyptian Fathers, as a reading of the homilies of Abba Isaiah will convince the reader, is the divestiture by the ascetic of the data of sense-perception in order for the ascetic directly or intuitively to cognize intelligible realities. This is also the import of St Gregory of Nyssa’s own doctrine of mystical ascent.
St Thomas then refers by author, title and chapters to Origen’s Peri Archon, to the places where Origen develops his doctrine that human souls and angels are of the same species. This is the cosmological doctrine that men and angels are minds (noes) of the same kind, a doctrine that in Chapter III, above, we saw to be expounded by Evagrius Pontikos in the Kephalaia Gnostica; this is a doctrine that was condemned by the Fifth Ecumenical Synod.
It should be noted, however, that the Fifth Ecumenical Synod nowhere addressed or condemned the notion that the human being could in this life attain to an intuitive cognition of intelligible realities; that is an issue different from the cosmological issue of the supposed identity of human souls and angels. It seems to us that the denial of the possibility of a natural intuitive cognition of intelligible realities by humans in this life is St Thomas’ personal Aristotelian position, one in which he departs from the older tradition of the Roman Catholic Church as represented by St Augustine. That is, this is St Thomas’ Aristotelianism as applied to human cognitive psychology.
The question whether man can know God directly is somewhat more complex: St Augustine certainly taught that the mystical experience or sight of God himself was possible in this life, but he certainly also reserved the fullness of it for the next life.
St Thomas then discusses the nature of the union of the soul with the body. Here his analysis is very detailed and depends on Aristotle’s psychology and metaphysics; we cannot hope to present his analysis in detail. His first position is that the intellectual part of man is united to the body as form to matter. The significance of this can be seen in the fact that this position entails a rejection of the Platonic doctrine that the soul uses the body as a tool, that the soul dwells in the body as in a house, that the soul merely puts the body into motion. For St Thomas, following the metaphysic of Aristotle, the connection between the soul and the body is quite importantly different. Unfortunately, it is impossible to convey the nuances of St Thomas’ thought on this matter without a thorough introduction to Aristotelian metaphysics. Suffice it to say that in one of the passages of On the Making of Man that we quoted in Chapter III, above, St Gregory of Nyssa clearly stated that the soul used the body just as a flutist uses the flute. Moreover, St Augustine very clearly teaches a Platonic doctrine of the relation of the soul to the body, insisting that the soul uses the body as a tool. And we have seen in Chapter III that Evagrius teaches that the soul dwells in the body as in a house.
There is in the authors a completely different orientation, the difference being precisely that between Plato (St Gregory of Nyssa, St Macrina, St Augustine and even Evagrius) and Aristotle (St Thomas Aquinas). However, it seems to us that, if it be possible, St Augustine is on this matter even more Platonically oriented than the Orthodox Church. However, it would take us far afield of our goal to pursue the matter of St Augustine’s dependence on Plotinus, the Neoplatonist.
However let us here present a summary of St Augustine’s anthropology: Man is composed of body, soul and spirit. The body is material. The soul itself is an autonomous, immaterial substance. It is immortal and incorruptible. Without the body and soul, there is not man. The soul contains the vivificatory function; it is the vital principle in man. The soul is in every part of the body taken as a whole and in every part of the body taken in particular. Man has only one soul, which is an intelligible substance made to rule the body: ‘Therefore man, as he appears to man, is a rational soul using a mortal and earthen body.’ The soul is a rational and intelligent substance from the beginning of its existence, although its reason and intelligence are dormant. St Augustine treats the nature of the union of the substantial soul with the body which it animates as a profound mystery. However, the relation of the soul to the body is that of the artisan to his tool. St Augustine is quite explicitly Platonic on this point, even more so, in our view, than St Gregory of Nyssa. As Gilson says: ‘This definition of man, where the emphasis is placed with such insistence on the hierarchical transcendence of the soul with respect to the body, accords with the profound tendencies of Augustinianism.’ The spirit, in the sense that interests us here, is the rational part of man.
In discussing his own point of view, St Thomas observes that the nature of any object whatsoever is manifested by that object’s operation. But, he says, the proper operation of man, insofar as he is man, is to understand, through which thing he transcends all the other animals. This is very important to grasp: it is the mind (Latin: mens; = Greek: nous) which makes man different from the other animals. In this, both St Thomas and St Gregory of Nyssa agree. Moreover, one of the foundations of St Augustine’s Trinitarian theology is the notion that it is the mind (mens) of man which is the image of God in man: St Augustine takes this doctrine so far as to derive the mutual relations of the Persons of the Trinity from the triadic relations he discerns within the human mind (mens) and its operations, this approach being valid, in his view, precisely because the human mind (mens) is an image of the Holy Trinity. This identification by St Augustine of the image of God in man with the mind (mens) would not be possible if the mind (mens) were not the distinctively human part of man, for the image of God must reside in what is human in man. However, we shall see that the interpretation of what ‘mind’ is differs among the three theologians: St Thomas Aquinas, St Gregory of Nyssa and St Augustine.
St Thomas states that although by its nature the human soul is made to be united to the body, it can exist outside the body, even though that is not its natural state. Of course, St Thomas here wishes to preserve the survival of the human soul after death. In this he is departing from Aristotle’s psychology—although Aristotle himself is ambiguous on the matter—as he does whenever he wishes to preserve an aspect of his psychology which he considers to be demanded by Christian revelation but which is not to be found in Aristotle.
 ST Ia, 75. Let us make a brief remark on references to the Summa for those who are not familiar with the work. The Summa is divided into three parts. The second part is divided into two sub-parts. Each part or sub-part is divided into a numbered series of questions, and each question has a variable number of articles (or sub-questions), which are themselves numbered. Within each article, St Thomas follows a fixed form: He presents an assertion that something seems to be or not to be the case. This assertion is always the contrary of his own opinion. He then presents a numbered list of assertions from his philosophical or theological opponents or predecessors which support the opinion contrary to his own. These are called the objections. He then presents his own opinion in the contrary assertion, and proceeds to develop it in the body of the article. He then presents one by one his reasoned replies to the objections. Thus, references to the Summa have the form ST Ia, 85, 1 or ST Ia IIae 10, 2, ad 1, where, in the first example, the ST refers, or course, to the Summa Theologiae, the Ia refers to the first part (which has no sub-parts), the 85 refers to Question 85 and the 1 refers to Article 1 within the question (implicitly, to the body of the article); or, where, in the second example, the reference is to the first sub-part of the second part of the Summa, Question 10, Article 2, Reply to Objection 1. Reference to any edition of the Summa will make the matter clear.
 ST Ia, 75, 1.
 See Chapter I.
 ST Ia, 75, 2.
 From ST Ia, 75, 2; translated by V. J. Bourke: Bourke p. 111.
 ST Ia, 75, 2, ad 2.
 ST Ia, 75, 3.
 Arist–Soul 429a27–9.
 E.g. Arist–Soul II, 1, 413a4–10; III, 4, 429a34–429b6.
 Arist–Soul 430a24–8.
 ST Ia, 78, 4.
 Copleston A, pp. 170–1.
 ST Ia, 75, 4.
 In ST Ia, 75, 5.
 Migne 34 Homily 7, Questions 6 and 7, col. 528A.
 ST Ia, 77, 5, ad 1.
 ST Ia, 75, 5, ad 3.
 ST Ia, 75, 6.
 ST Ia, 75, 7.
 Volume II.
 Volume III.
 ST Ia, 75, 7.
 ST Ia, 76.
 ST Ia, 76, 1.
 De moribus ecclesiae, I, 27, 52, quoted by Gilson in Latin in Gilson Aug p. 58, fn. 2.
 Ibid. p. 58.
 ST Ia, 76, 1.
 ST Ia, 76, 1 ad 6.
 See fns. 24–6.