1. The Object of Psychology
The object, perhaps the twofold object (or precise scope of inquiry), that one will assign to psychology depends, of course, on the general tendency of one's philosophy. If, for example, we lean to the spiritualist view of St. Augustine or Descartes, we shall naturally incline to the position that the object of this science is the activity of the soul considered in itself, apart from any reference to the body. If, on the other hand, we are committed to the preconceptions of materialism, we shall be disposed to reduce the domain of psychology to the physiological, or even to the physical level. But if we adopt a middle ground, such as the moderate spiritualism of Aristotle, the object of psychology will include something of each of these divergent determinations.
Our approach, it need hardly be said, is that of Aristotle. But even here two choices are possible.
a) Mental life and life in general. - In the view of Aristotle all manifestations of life can be called psychological facts; psychology would then be defined by life itself, and all living beings, including those below man, namely, animals and plants, would belong to the science of the soul. Following this view, one can say that the object of psychology is:
the living being in so far as it is the principle of vital activities.
The justification for this position lies in the basic Aristotelian classification of all activity into two main types: transitive and immanent. Transitive activity produces a change upon something other than the subject; whereas immanent activity originates in and works for the perfection of the subject. On the basis of this division, beings are nonliving if they have only transitive activities, and living if they are endowed with immanent activities, or can move themselves. Accordingly, a more precise determination of the object of psychology would be to define it as:
those beings endowed with immanent activity or the power to move themselves, considered as such.
With this, the scope of psychology is clearly marked off; only it leaves the difficulty, in some cases, of deciding whether a given operation is a vital activity or not.
b) Psychology and consciousness. - According to some schools somewhat different terms, namely, in terms of consciousness. As they see it, the proper scope of psychology is the realm of consciousness, or whatever is accessible to consciousness. It will be readily seen that in this conception one whole area of vital activity, the whole infraconscious realm, is eliminated from the scope of this science. Excluded, therefore, is the life of plants as well as certain aspects of animal and human life. In short, the object of psychology would be considerably restricted.
For our part we have no intention to deny that the fact of being conscious and self-reflective is one of the most striking characteristics on certain levels of vital activity. Nevertheless, with St. Thomas we believe that psychology should be defined with respect to vital activity as a whole, because the distinction of living and nonliving is more basic than that of conscious and nonconscious. Doing so, moreover, we are following in the footsteps of authentic Aristotelianism.
2. The Methods of Psychology
Since considerations of method are of little value previous to and apart from practical application, we shall limit ourselves to briefly clarifying two points.
a) Introspection and the objective method. - Like every science, psychology must be founded on the knowledge of facts. On this point the philosophy of Aristotle is in perfect agreement with the demands of modern science. But the facts of psychology, at least those occurring on a higher level, are unusual in that they can be obtained by two different methods: objectively, in so far as they are of a piece with the world perceived by the senses; and subjectively, in so far as they are conscious experiences. To this twofold approach to psychological facts correspond two methods, called objective and subjective.
The subjective method, also referred to as introspection, is peculiar to psychology. The ancients themselves used it, though not so systematically as the moderns. Among the latter two contrary views regarding introspection have prevailed. Some deem it the only means of creating a genuine science of psychology; whereas others, more mindful of its rather elusive and subjective character, feel that it has little scientific value.
There is something to be said for each of these opinions, and the truth would seem to lie in between. Certainly, introspection must be acknowledged as a normal and reliable source of information for psychology, indeed as the chief means of investigating the whole field of higher activities. But because of the evanescent nature of conscious states, and the impossibility of submitting them to direct and exact measurement, the method of introspection carries with it a degree of uncertainty. In any event, it has always to be controlled and completed by objective information.
The objective methods include all those procedures by means of which life and its activities can be studied from the outside, as it were. Since mind is linked to matter and the mental to the physical, the life of the soul is reflected in actions and reactions of the body. I knee, there is no reason why the soul should not be studied through the medium of bodily activities. As for Aristotle himself, we may note that he would be the last to scorn this procedure. We shall, in fact, see that his initial approach to living things is precisely from the viewpoint that they are bodies, forming part of the physical universe, even as the material elements; his inner analysis of their specifically vital functions comes later. In this respect at least, Aristotelian psychology is abreast of the most up-to-date conceptions of that science. Doubtless, modern techniques leave the former far behind, but this is only a difference of degree. Methods are more refined, not basically different.
The truth of the matter is that psychology can employ both methods, both introspection and objective gathering of data, using - there is no reason why not - the most modem techniques of experimentation. Nor is there any reason why, under proper conditions, it should not have recourse to the comparative or differential methods that have been made available, for example, by animal psychology, pathological psychology, and genetic psychology. The point we wish to make is simply that every source or method of information is legitimate, provided that it does not pretend to be the only one, and does not impose unfounded or unverifiable preconceptions.
b) Philosophical method and theological method. - In the philosophy of St. Thomas we face an additional question of method. Aristotle, as was but natural, developed his ideas within a purely philosophical framework. In his commentaries St. Thomas adopts the same point of view, but in his theological works the Angelic Doctor takes another line. To see the difference we have only to compare the procedure followed by Aristotle in the De Anima with the order followed, for example, in the great psychological treatise embodied in the Prima Pars, questions 75 to 89. The former work begins with the physical world, in which some bodies are found to have the remarkable property of being able to move themselves. These are living bodies, whose activities are then studied, beginning with the lowest to the highest, until we come to an activity that is absolutely independent of matter. With this activity, which is thought, we stand at the threshold of another world, the world of spirit. Such is the purely philosophical procedure, which normally goes from the less abstract to the more abstract, or from the sensible to the intelligible. In the Summa Theologiae, however, man is immediately introduced, not as a body among other bodies, but as a created being, composed of body and soul, which latter is directly produced by God and forms the principal object of inquiry. Here the order of the questions and the importance attached to each are, clearly, quite different.
Consequently, Thomistic psychology admits of two different yet authentic presentations. One may follow the plan and view point of the De Anima, or take the position adopted in the psychological portions of the theological works. The latter course has the advantage of giving a more orderly account of St. Thomas' own views. But the De Anima also has its advantages. Among other things, it takes us to the very source of St. Thomas' doctrine. What is more - and this is of capital importance - it stays within the bounds of purely philosophical speculation, which, as Thomism rightfully teaches, must come to the spiritual by way of the material.
Therefore, without neglecting the rich psychological contributions of the Summa, we shall follow the step-by-step upward treatment observed in Aristotle's De Anima, going from the general to the particular, from the lowest degree of life to the highest. Thus, we shall begin with the study of the soul, first considering it in general as the principle of life, and then its faculties. Next we take up in order the three basic degrees of life that have always been attributed to man, namely, vegetative, sensitive, and intellectual life. Lastly, in the concluding portion, we come back to the particular problem of the human soul, a problem that naturally presents itself at the point where the soul's higher activities are discussed. Accordingly, the present work may be divided into the following main headings: