1. The Problem of the Soul
a) Defining the problem. - The problem of the soul is one with the problem of life. Earliest man himself appears to have been occupied with it; indeed, it could hardly have failed to draw his attention. Man has always been struck by the fact that certain beings in nature distinguish themselves from others by an organization that is remarkably unified and by a behavior that is original and utterly unlike that of other beings. It was but natural to wonder whether these unique qualities displayed by such beings should be attributed to their having an intrinsic, invisible principle, a soul, whose appearance is simultaneous with the very moment of their begetting and whose disappearance coincides with the moment of their death. Closely connected with the problem of the soul, moreover, have always been religious and moral questions, with the result that belief in the soul has taken many and extremely varied forms. More than one scholar has attempted to retrace the history of this belief in one form or another.? Our present concern, however, lies along different lines.
To begin with, let us make it clear what we mean by soul. In general, the soul is seen as a principle of life. In saying this, we are using the word "soul" in its widest sense, according to which it means nothing more than the first and innermost principle of life. When searching for first and ultimate principles, moreover, one can focus one's attention on more immediately evident elements relating to the inquiry. For example, in studying the nature of life, one can concentrate on various organs of a living being, such as the heart, or on a particular faculty, such as the intellect. But these would not be ultimate considerations. It is only in taking up the study of the soul itself that we come to grips, as it were, with the ultimate, intrinsic explanation of the dynamic force and energy that characterize living things. As St. Thomas remarks: "To seek the nature of the soul, we must premise that the soul is defined as the first principle of life in I hose things which live." 3 To forestall every ambiguity, it should further be noted that in the present chapter we are speaking of the soul in general, as common to all living things in nature, to vegetables and animals as well as to man. The questions to be discussed, therefore, are those that concern the soul in general. Those that pertain specifically to the human soul as an immaterial form and the principle of that higher life which is in man, will be dealt with later.
b) The study of the soul in Aristotle and St. Thomas. - As we have previously said, Aristotle, on the basis of his own study and reflection, gradually abandoned his earlier view of the soul, which was much like the ultra-spiritualist doctrine of Plato, and in its place adopted what may be called an animist interpretation, making the soul the form of living beings. This is the view that emerged as the distinctive feature of his own thought on the nature of living things. It would be most interesting to review in detail the course of this intellectual evolution in Aristotle, revealing as it does the profound study and insight with which he pursued the subject. But here again we can only refer the reader to the work of specialists in the field.9 For our purpose we shall simply take his doctrine as it was in its state of full development, which is to say, as expounded in the De Anima.
Clearly, the essential core of this work is the definition of the soul. As he had done in Book A of the Metaphysics, when he was investigating the problem of causes, so in the De Anima Aristotle begins by setting forth and submitting to critical examination the theories of the soul held by others before him (Bk. II, chaps. 1-2). In the historical part of his exposition the Stagiritc, like his predecessors, first considers the soul as principle of movement, and then as principle of sensation. Most of the arguments making up the discussion are directed against various materialist interpretations of life and its manifestations, but the ultra-spiritualist dualism of Plato also comes in for criticism.
In the Commentary on the De Anima St. Thomas follows the text before him very closely. In some of his other writings, however, he treats this whole question of the soul in a more personal manner."' As a matter of fact, when St. Thomas is engaged in a theological work, the framework for the discussion of the soul is quite different, though even here his teaching in the matter, apart from the question of immortality, is basically the same as that of his master. In a theological setting the immortality of the soul and its creation by God are simply taken as revealed data, and the principal point at issue is the possibility and the manner of its union with a body. In St. Thomas, moreover, the discussion as a whole takes a more complex turn by the opinions of ancient and Arabian commentators being brought in, notably those of Alexander of Aphrodisias and Averroes.
As we shall see presently, in their treatment of the soul both Aristotle and his disciple address themselves primarily to two general streams of thought, one opposed to the other, namely, materialist mechanism and absolute dualism. Compelled to reject both as unsound, master and disciple brought forth their own solution in terms of hylomorphism, or more precisely, animism, declaring the soul the form of the body. Our next step, therefore, is to give a brief account of the criticism directed against mechanism on the one hand and Plato's dualism on the other.
2. The Criticism of Mechanism The materialist or mechanist view of the soul is not the exclusive hallmark of contemporary thought. In one form or another Aristotle himself, not to say his earlier as well as later followers, was confronted with this doctrine. This being so, one may legitimately ask what they thought about it.
a) For the answer to this question we may go to the first part of the Summa, question 75, where the matter is treated in terms that are very clear and to the point. The first article asks whether the soul is a body. The answer is no, because whatever it is that distinguishes a living from a nonliving body, it cannot be another body; else, all bodies would have to be deemed alive. As for the human soul in particular (art. 2), it must further be stated that the higher operation of this soul, the act of intellectual knowledge, cannot have its principle in a body or bodily organ. In other words, if the human soul were corporeal, possessing a determined, corporeal nature, the intellect would be corporeal, and it could not know other things of similar nature. Were this the case, it would not be true to say that the intellectual faculty is in potency to all intelligible objects.
Granted that the soul is not a body pure and simple, in the sense of a stark materiality, is it perhaps some sort of structural blend or arrangement, resulting from the various elements being reduced to a composite? St. Thomas knew this theory in two forms closely alike, one, attributed to Galen, viewing the soul as a "complexion," and the other, traceable to Empedocles, as a "harmony." 11 The gist of this theory is that living bodies as well as others are actually composed of nothing more than material elements; but in the former, it is said, there exists a certain proportional arrangement which, though not a true formal principle, being an effect rather than a principle, is nevertheless supposed to account for the organization and activity of the whole. St. Thomas makes it clear, however, that this concession will not save the situation. Neither mere corporeal structuring or texture ("complexion"), nor a harmony, can perform the function of a principle of movement, nor can it serve as an explanation why we sometimes act contrarily to the body's own inclinations. Also, it cannot account for such operations as knowledge, which plainly surpass the active and passive capacities inherent in material elements. All of which means that the principle of life has to be a reality of quite another cast.
b) The foregoing arguments are of a general nature. For the sake of illustration, therefore, let us see how St. Thomas deals with a specific point regarding the theory of Empedocles, namely, the phenomenon of augmentation or growth in living things.15 According to the theory this effect is sufficiently accounted for by the natural motion of light and heavy elements, without recourse to a soul. The downward thrust of the roots is due solely to the natural downward movement of the element of earth, which is heavy, while the upward growth, it is claimed, comes from the natural upward movement of the element of fire, which is light. But, says St. Thomas, this is an impossible explanation, and for several reasons. First, up and down, he believes, are not to be taken in the same sense for the world as a whole and for individual living beings (the upper part of a plant, for instance, being its roots, the lower parts its foliage). Furthermore, the interaction of such contrary forces would make for disrupting the living being, unless it were held together by the greater unifying power of the soul. And as for the assertion that fire alone is the active cause of growth as well as nutrition, St. Thomas answers, yes, fire is indeed a cause in this process, but simply as an instrument of a principal cause, which is none other than the soul. Purely physical energies would tend to produce indefinite increase, whereas growth that is limited and clearly defined presupposes a regulating principle, or measure, that is above and beyond the purely physical order.
So much for St. Thomas' handling of the materialist and mechanist interpretation of the phenomenon of growth. Doubtless, his arguments, in part at least, appeal to certain physical theories now outmoded. For all that, however, the substance of his proofs is not without real value or interest for us. Among other things, his procedure makes it clear that the phenomenon in question is a living process displaying original and distinctive qualities. The explanation proposed by the materialist is refuted by the characteristic behavior of vital transformations being brought into careful and accurate contrast with mere physical operations. Beyond this, a serious attempt is made to give an authentic account of vital activities by putting forward the existence of a governing principle that is not of the purely material order. On the whole, even though scientific facts are now better controlled and more accurately observed, a demonstration of this kind, carefully applied, could still have real value.
c) With reference to what we have just said, it is worth noting that in our day biological mechanism has again become the target of criticism, this time from some recognized scientists, whose views are commonly known as "vitalism." This label, it must be confessed, includes a rather wide assortment of theories that are not without differences of their own. Nevertheless, all agree in seeking to explain vital phenomena by some force or power that goes beyond the mere modifications of matter, the inference being, quite correctly, that purely material alterations are not enough to account for the unique character of such phenomena. Among this school of thought is a group called "neo-vitalists," which includes such acknowledged scientists as Driesch, Remy Collin, and Cuenot. These, among others, frankly assert the need of a vital principle in terms that are strikingly reminiscent of the Aristotelian entelechy.