Chapter IV -- 5
St Thomas next denies the position of Averroës (1126–98), the Muslim philosopher, that all men share in a single ‘active intellect’, a position based by Averroës on his own interpretation of a passage of Aristotle which concerns the ‘active mind (nous)’, a passage of Aristotle which has always been in dispute. That is, St Thomas’ position is that each man has his own ‘active intellect’ and does not merely share in a universal ‘active intellect’. While today we might take this position to be obvious, it is well to remark that Averroës, for example, did not.
Moreover, the significance of
We here see an important point: The doctrine that men do not participate in a collective mind or even in a collective unconscious has today in the West by and large come to be the dominant model of man, even in everyday life. One could conceive of a different historical trend in a different cultural milieu which would have left a legacy of a different view of man. These anthropological positions of St Thomas Aquinas, whether they are the source or an intermediary or merely a manifestation of an underlying tendency in Western thought, have come to be so deeply rooted in the Western conception of man that today we take them for granted without serious examination.
St Thomas next makes a very important assertion: each man has only one soul. Now this may also seem gratuitously obvious to us, but the discussion of it is very important. For we saw in Chapter II, above, that St Macrina, following Aristotle, described the vegetative, animal and human souls as forming, in creation, a hierarchy. The reader will recall that St Macrina adapted that aspect of Aristotle’s psychology to the Genesis account of creation in order to explain the origin of the passions, stating clearly that each man had the functions of the animal soul in him and that this presence of the functions of the animal soul in him was the origin of the passions in man.
St Thomas is addressing the same notions and discussing what it means for a human being to have vegetative and animal functions in himself in addition to the distinctively human function of, for St Thomas, intellectual understanding. For, St Thomas says, this cannot mean that the human has a vegetative soul and an animal soul and a human or intellectual soul—three souls. That, he says, would be absurd. The mature man has only one soul, the intellectual soul, but that intellectual soul possesses all the functions (or, powers) of the vegetative and animal souls, just as the animal soul—of a tiger, say—also possesses all the functions of the vegetative soul. Moreover, St Thomas says, the human soul possesses, as do the animal and vegetative souls, all the lower functions required by Aristotelian metaphysics for a complete account of an existent being.
The reason St Thomas adduces for his position is that an argument for multiple souls would work under the Platonic conception of the soul, which views the soul as a separate substance which moves the body, but not under the Aristotelian conception of the soul as the form of the body. Indeed, St Thomas asserts that Plato taught that a man had a multitude of souls of different kinds.
It must be understood here what form means to Aristotle and to St Thomas. The classic metaphor, due to Aristotle himself, is that the form is like the form of the man that will be placed in the marble or bronze to make the statue: the marble or bronze is the matter of the statue. The actual subsistent being is the statue of the man, made up of form—the shape of the man—and matter—the marble or the bronze. The completed statue is the actual substance, the thing that actually exists: the form, although real, can be separated from the matter only in thought, not in act. That is, it is the complete statue of the man that exists and we can separate the form of the statue, the shape of the man, from the matter of the statue, the marble or bronze, only in our thought and not in our actions, although the shape of the man is real and not fictitious. This is evident: the shape of the man is there, but we cannot abstract it from the marble or bronze except in our thought. This of course is Aristotelian realism. The relation of form and matter between the soul and the body is a much closer relation between soul and body than the relation posited, according to St Thomas, by the Platonic conception of the soul as a separate substance that moves the body. The Platonic conception of the soul is much closer, we ourselves might say, to the ‘ghost in the machine’ that has been attacked by materialistic philosophers even in our own time than is the Aristotelian conception of the soul.
Now the matter is somewhat complicated by the nature, according to St Thomas, of the human intellectual soul in relation to the vegetative and animal souls. For the vegetative and animal souls are strictly forms in the sense that they have no autonomous or subsistent existence apart from the matter of the body of the plant or animal whose form they are: they are separated from the matter of the plant or animal only in our thought, in our consideration of the living plant or living animal, and when the plant or animal dies, then its form or soul ceases to be. But the human intellectual soul is subsistent: it continues to exist after the death of the man.
Both Aristotle, and, following him,
St Thomas formally asserts that there is only one substantial form in a man, his intellectual soul; that that soul contains ‘by virtue’—by its operations, by its faculties—the nutritive (vegetative) and sensitive (animal) souls and also all the other inferior forms required by Aristotelian metaphysics; and that that soul, by itself only, does all that the inferior forms do in other earthly creatures. What St Thomas means is this: the human intellectual soul is distinctive in that it is a substantial form which possesses the power of ratiocination, and it is the only soul that a mature man has; but that substantial form also possesses the functions of the vegetative and animal souls, and indeed all the functions of all the inferior forms. St Thomas needs to say this for the following reason: The characteristic of the human soul is that it is intellectual, and explicitly in St Thomas’ thought this has nothing to do with the vegetative or animal functions, nor, as we have seen, does the human intellect have any dependence on the body. Hence, it is necessary for St Thomas to assert that that intellectual soul possesses the lower functions or powers also, in order to account for the vegetative and animal functions that are connected to the body and that men obviously have (for example, nutrition and sense-perception), and for all the other inferior functions that would be needed to give an account of a whole living man composed of soul and body and dwelling on the face of the earth—but without for all that conceding that the human being has more than one soul. This doctrine was challenged by later Scholastics working in the Augustinian tradition.
This doctrine of St Thomas is important for an understanding of the concept of brain death. For since there is only one soul in a man, which accounts for all aspects of his being alive—and indeed, for all aspects of his being—, St Thomas’ doctrine does not allow for the conceptual separation of the higher intellectual or personal functions of the man from the lower vegetative or animal functions, which is what is done by the doctor in defining the concept of brain death. For the doctor proposes to measure electrically the higher brain centres, thereby to ascertain whether the patient has these higher centres in operation. The doctor assumes that the lower brain functions are functioning, those that account, in St Thomas’ and Aristotle’s terminology, for the vegetative functions of the patient: pulse and respiration and such-like. The doctor then proposes to declare the person dead when he establishes that the higher brain functions are no longer present, although the lower brain functions are. But St Thomas’ doctrine of the unity of the human soul does not permit this: if the lower functions of the brain are in operation, that is only possible, on his account of the human soul, if the human soul is present in its entirety: the human soul accounts for all the lively functions of the patient and that soul is one. Hence, the soul of the patient is either present, in which case the higher functions are merely hidden by the damage to the body—a position taken by Aristotle himself with respect to the sight of man in cases of damage to the eye, and by St Thomas himself with respect to the functioning of the intellect in cases of damage to the body—or the soul of the patient is absent and the person is dead: all lively functions, whether intellectual, animal or vegetative, have stopped, including pulse and respiration. But this is certainly not the position of the doctor enunciating the doctrine of brain death. Moreover, since St Thomas explicitly asserts that the higher intellectual functions of man do not depend on the body, on his account of the human soul the presence or absence of those higher functions cannot be determined by a measurement of the electrical activity of the cerebral cortex or, indeed, of any other part of the body.
In his view of the unity of the human soul, St Thomas is quite similar in intent to St Gregory of Nyssa in On the Making of Man. The difference is one of emphasis and philosophical orientation. For St Gregory of Nyssa clearly takes the position that the soul is one and that it is present even in cases where damage to the body prevents expression of the powers of the soul. St Augustine also takes the position that the human soul is one.
St Thomas makes the very important assertion, one that in Chapter III we already saw St Gregory of Nyssa to make in On the Making of Man, that a man’s soul is completely contained in every part of the man’s body. The similarity of the two doctrines might seem striking to the reader but the fact that St Thomas quotes St Augustine in expounding his own position should alert us that St Thomas’ position is derived from St Augustine. For St Gregory of Nyssa and St Augustine are both considered to be Neoplatonists: the close similarities between the doctrines of St Gregory of Nyssa and St Augustine seem to arise on the one hand from the common doctrine of the Church—St Gregory of Nyssa and St Augustine were roughly contemporary—and on the other hand from the reliance of each on Neoplatonism. One might say that the close similarities between the anthropological doctrines of St Thomas Aquinas and St Gregory of Nyssa arise from the reception by St Thomas Aquinas of positions of St Augustine, which positions have the relation to those of St Gregory of Nyssa that we have just stated; and that many of the differences between the anthropological doctrines of St Thomas Aquinas and the anthropological doctrines of the Orthodox Church arise from St Thomas Aquinas’ modifications of Augustinian positions in order to adapt them to Aristotelianism as he understands it.
St Thomas then turns to a general discussion of the powers of the human soul. For the most part, this discussion is quite theoretical. However, St Thomas formally asserts that the soul has many powers. These powers might be considered to be faculties. Here, it is well to remark that for St Thomas the soul is simple and not complex, just as it was for St Macrina, and just as is was for St Augustine. Hence, these powers cannot be considered to be different compartments of the intelligible soul in the way that the body has different organs located in different spatial positions: they are powers of the soul in the sense that they are things that the soul can do.
Since these powers are discovered by St Thomas by logical analysis—following Aristotle surely—it might be thought that these powers are really without objective reality, that they are nothing more than the fruit of a logical analysis of human actions and behaviour, or even of a logical analysis of the way we speak about human actions and behaviour. However, St Thomas clearly intends us to understand that these powers are objectively real. This of course is his Aristotelian realism. In no way would he wish us to understand that his analysis was conventional or arbitrary, nor would he consider that he was merely providing an analysis of how we talk about human actions in ordinary language: he believes that he is providing an objective analysis of the real powers, or capacities, or capabilities, or modes of operation, of the human soul. Moreover, St Thomas not only takes his realism for granted, but he also assumes that by logical analysis, sometimes of a very minute kind, he can determine the objectively real relations of these powers of the soul the one to the other and to other objects in his Aristotelian metaphysical speculation. The result is an extremely detailed analysis of human action based on these powers, on their mutual relations and on their relations to other objects in Thomist metaphysics.
St Thomas asserts that these powers are distinguished the one from the other both in terms of their objects (what things they work on) and in terms of their actual operations (what they actually do).
Moreover, St Thomas asserts that these powers have an order among themselves. Here we see an aspect of St Thomas’ thinking which gives it its particular or peculiar character: this very detailed analysis and ranking of abstract objects such as the powers of the human soul.
St Thomas asserts that the subject (Latin: subjectum) of the powers of the soul is not the soul, but the whole composite of body and soul. Here it might be remarked that in Chapter II, we ourselves, following the analysis of St Macrina and her brother St Gregory of Nyssa, developed the doctrine that the person was to be identified with the mind (nous). This is a more Platonic doctrine. St Augustine also has this orientation: much of his thought would be unintelligible without such an identification of the person with the person’s conscious experience of his own mind (mens). St Thomas, however, asserts that the subject—we ourselves take this to be equivalent to person—is the composite of body and soul. That the distinctive part of the human soul is the mind (nous) is not in issue here; St Gregory of Nyssa, St Augustine and St Thomas are in agreement on that point; what is in issue is how we are to identify the person. The concept of the person has implications both in bioethics and in the doctrine of prayer.
When we discuss St Thomas’ theory of action, we shall see that this doctrine that the subject (subjectum) is the composite of body and soul creates an ambiguity in his analysis of the mutual relations of the intellect and the will in a human action. For St Thomas analyses very minutely, in the way we have just mentioned, the mutual interactions of the intellect and the will when a person is coming to do a human action. But the question arises: in these mutual interactions of the intellect and the will, where is the humanly free person?
St Thomas asserts that when the soul departs at death from the body, then the soul loses those powers which depend on the body—that is, all those powers, other than the intellectual ones, that have been referred to above. The importance of St Thomas’ previous assertion that the intellectual functions of man in no way depend on the body can be seen here, for according to St Thomas’ own argumentation, if the intellectual functions of the soul depended necessarily on any part of the body, then they too would cease operation when the soul departed from the body, something that would be contrary to his doctrine of the survival after death of the soul in a conscious condition.
The reader may recall from Chapter I that St Macrina attacked a notion, evidently due to Epicurus, that when a man died, then his soul dissipated. Of course, Epicurus viewed the human soul as something material, something that would dissipate like a gas, whereas St Thomas, following Aristotle, has a more sophisticated conception of the vegetative or animal soul as the form of the plant or animal. And, of course, St Thomas is preserving the survival of the human soul after death: he is merely asserting that the human soul loses those vegetative, animal and other inferior functions that depend on the body even though it retains the essentially human function of the intellect, which function, of course, does not in his view depend in any way on the body.
Recall that St Thomas has already remarked that when the human soul departs from the body, then it understands intuitively in an angel-like manner. This can now be seen to be necessary for St Thomas to assert, since, by his own admission, the soul after death no longer has the possibility of understanding by means of the sense-perceptions that it had when it was in the body, those powers related to sense-perception having been lost along with all the other powers that it had which depended on the body. This doctrine did not receive universal approbation from later Scholastics.
However, St Thomas goes on to say that the human soul, when it departs from the body, bears with it ‘by virtue’ those lower powers that it has lost. That is to say, since the soul no longer is united to the body, these powers can no longer be exercised, but, were the soul once again to be united to the body, then these powers would once again be able to operate. His comment on this point is very brief.
It is well to recall from Chapter III, that, in Chapter 15 of On the Making of Man, St Gregory of Nyssa asserts that the mind (nous) is the true soul and that the lower powers of the soul—the functions which correspond in man to the vegetative and animal souls—are ‘but a certain enlivening operation which has been honoured together with the name of the soul’. Now, strange as it may seem, a Platonically-oriented Cappadocian of the Fourth Century and a mediæval Scholastic Italian of the Thirteenth Century rigorously following Aristotle and working largely at the University of Paris are largely in agreement on the matter. For if we except the different modes of expression, then both St Gregory of Nyssa and St Thomas are saying the same thing: for both, what is essentially human is the mind (Latin: mens; = Greek: nous); however, the human soul also possesses the vegetative and animal functions associated with the Aristotelian typology of the vegetative, animal and human souls. Both St Gregory of Nyssa and St Thomas want to assert, however, that these lower functions are not intrinsic to the human identity of the human soul. This is but one of the places where we see the striking resemblance that we have already noted between the anthropology of St Thomas and that of St Gregory of Nyssa, a resemblance that we have taken to be due to St Thomas’ dogmatic dependence on St Augustine.
 ST Ia, 76, 2.
 Arist–Soul III, 5, 430a24–8.
 ST Ia, 76, 3.
 ST Ia, 76, 4.
 ST Ia, 84, 4.
 See Chapter III.
 ST Ia, 76, 8.
 ST Ia, 77.
 ST Ia, 77, 2.
 ST Ia, 77, 3.
 ST Ia, 77, 4.
 ST Ia, 77, 5.
 ST Ia, 77, 8.
 ST Ia, 77, 8, ad 1.
 See Section 13 of Chapter III for the full quotation.