§ 4. What, then, is the logical justification for that elaborate transformation of experience which is necessary to bring it into the form presupposed by psychological science? In principle the question is not hard to answer. The “ideas,” “mental states,” and so forth, of Psychology are, as we have seen, symbols which we substitute for certain concrete actualities, and, like all symbols,[[169]] they only partially correspond to the material they symbolise. But, like other symbols, they are admissible as substitutes for the things symbolised on two conditions: (1) that the individual symbol corresponds to that which it symbolises according to a definite and unambiguous scheme, and (2) that the substitution of the symbol for the thing symbolised is required in order to make the latter amenable to such manipulation as is necessary for the solution of some particular class of problem. Now, there can be no doubt that the first of these conditions is fulfilled by the translation of our actual experience into the introjectionist symbols of Psychology. For in the external or “physical” events which correspond to a “mental state,” I possess an unambiguous means of recognising the actual experience for which the mental state in question stands in the symbolism of Psychology. If the various physical “conditions” and forms of “expression” of the mental state are indicated with sufficient fulness and accuracy, they enable me to identify the corresponding actual experience when it occurs in my own life, or even to produce it experimentally for the express purpose of interpreting the Psychologist’s symbolism. The only question, then, that can reasonably be raised as to the legitimacy of psychological symbolism, is the question whether such a transformation of the actualities of immediate experience is demanded for the attainment of some specific purpose or interest.
It seems, I think, that the transformation is really required for more purposes than one. In the first place, one obvious use of psychological hypotheses is that, like the hypotheses of physical science, they assist us to calculate the course of events, in so far as it is independent of purposive interference of our own, and thus to form prudential rules for our own guidance in so interfering. This seems to be the principal use of those parts of Psychology which deal with the more mechanical aspects of mental life, e.g., the laws of the formation of fixed habits and associations by repetition, the gradual passing of voluntary into involuntary attention, and so forth. We are interested in studying the laws of habit and association, just as we are in formulating mechanical laws of physical nature, because we require to guide ourselves by such knowledge whenever we directly and intentionally interfere in the life of our fellows for educational, punitive, or general social purposes. Unless we can forecast the way in which our fellow will continue to act, so far as his behaviour is not modified by fresh purposive initiative, we shall be helpless to decide how we must intervene in his life to produce a given desired effect. Similarly, the direct moulding of our own future in a desired direction would be impossible apart from such knowledge of what that future is likely to be without intentional direction.
It may be said, of course, with justice, that, so far as Psychology presents us with such routine uniformities of succession, it is a mere supplementary device for making good the defects in our anatomical and physiological knowledge. If our physiological science were only sufficiently extensive and minute, we might reasonably expect to be able to describe the whole course of human action, so far as it is amenable to mechanical law, and exhibits routine uniformity in purely physiological terms. Instead of talking about the “association” of “ideas” or the production of a “habit” by repetition, we should then, for instance, be able to describe in physiological terminology the changes effected in a cerebral tract by the simultaneous excitement of two nervous centres, and to write the complete history of the process by which a permanent “conduction-path” arises from the reiteration of the excitement. Such a definite substitution of physiological for psychological hypotheses is pretty evidently the goal which the modern “experimental Psychology” has set before itself, and which it is constantly trying to persuade itself it has reached, in respect of some parts at least of its subject.
Nor does there seem any reason to doubt that, since the physiological counterpart of a routine uniformity of mental sequence must itself clearly be a routine uniformity, all psychological laws of uniform mechanical sequence might be ultimately replaced by their physiological equivalents, if only our knowledge of the structure and functions of the nervous system were sufficiently advanced. Hence Professor Münsterberg is perfectly self-consistent in arguing from the premisses that the sole function of psychological science is to provide us with mechanical uniformities of sequence by the aid whereof to calculate the future behaviour of our fellows, in so far as it is not modified by fresh purposive initiative, to the conclusion that the whole of Psychology is a temporary stop-gap by which we eke out our defective Physiology, but which must sooner or later cease to be of use, and therefore cease to exist as Physiology advances.[[170]]
It would, of course, remain true, even if we were to accept this view of the case without reservation, that Psychology is, in the present state of our knowledge, an indispensable adjunct to Physiology. For, while our knowledge of the physiology of the nervous system is at present too fragmentary and vague to be of much practical use in enabling us to forecast even the simplest sequences in the behaviour of our fellows, Psychology is, temporarily at least, in many respects in a more advanced condition. Thus, if it were necessary, before we could infer the probable effects of exposure to a particular stimulus on a man’s behaviour, to frame a workable hypothesis as to the physiological occurrences in the nervous system between the first reception of the stimulus and the issuing of the ultimate bodily reaction, we should still be waiting helplessly for the means of framing the simplest general judgments as to the probable effects of our actions on our social circle. This is because the nervous changes intervening between the reception of the stimulus and the reaction can only be rendered accessible to observation by devices which postulate for their invention an extremely advanced condition of physical science in general and of Physiology in particular. There is no direct method of translating the actual processes which we experience into an unambiguous physiological symbolism, or, vice versâ, of testing a physiological hypothesis by retranslating it into facts of direct living experience. On the other hand, when we have given the assumed conditions of the occurrence of the stimulus, it is comparatively easy to observe what follows on them in actual life, and to translate it into the introjectionist Psychology, or, vice versâ, to test a theory couched in terms of that Psychology by comparison with the actualities of experience.
For this reason psychological hypotheses are, in the present state of knowledge, an indispensable mediating link between actual experience and physiological theory, and if ever they should come to be finally superseded by purely physiological descriptions of human conduct, we may be sure that the triumphant physiological theories will themselves first have been won by the process of establishing psychological formulæ and then seeking their physiological analogues. This is illustrated in the actual history of contemporary science by the extent to which the cerebral physiologists are dependent for their conception of the structure of the nervous system on the previous results of purely psychological investigation. We might present the mutual relations of concrete experience, Psychology and nervous Physiology, in an epigrammatic form, by saying that the connecting link between the subject of experience and the brain of Physiology is the “mind” or “consciousness” of Psychology.
§ 5. It is, I think, questionable whether such a view as Professor Münsterberg’s does full justice to the interests which prompt us to the construction of the psychological symbolism. On his theory, Psychology, it will be seen, is essentially a science of routine or mechanical uniformities of sequence, just like the various branches of mechanical Physics. According to him, teleology must be ruthlessly banished from scientific Psychology. In other words, though all the actual processes of direct experience are pervaded by teleological unity of interest or purpose, yet in substituting our psychological symbols for the actualities we must deprive them of every vestige of this teleological character. Nor is this demand that Psychology shall translate experience into a series of non-purposive routine sequences an arbitrary one on Professor Münsterberg’s[Münsterberg’s] part. If the sole function of Psychology is to facilitate calculation and prediction of the course of events, so far as it is not controlled by purposive interference, Psychology must, of course, either follow rigidly mechanical lines in its descriptions, or fail of its object. But I would suggest that over and above this function of facilitating calculation and prediction at present fulfilled by Psychology as locum tenens for a perfected Physiology, Psychology has another and an entirely distinct function, in which it would be impossible for it to be replaced by Physiology or by any other branch of study. This function is that of affording a set of symbols suitable for the description, in abstract general terms, of the teleological processes of real life, and thus providing Ethics and History and their kindred studies with an appropriate terminology.
It is manifest enough that neither the ethical appreciation of human conduct by comparison with an ideal standard, nor the historical interpretation of it in the light of the actual ends and ideals which pervade it and give it its individuality, would be possible unless we could first of all describe the events with which Ethics and History are conceived in teleological language. Apart from the presence throughout those events of more or less conscious striving towards an ideal end, there would be nothing in them for the moralist to applaud or blame, or for the historian to interpret. Thus, if Ethics and History are to have their subject-matter, there must be some science which describes the processes of human life and conduct in terms of teleological relation to an end. Now, to what science can we go for such descriptions? From our previous examination of the postulates of physical science, it is clear that the requisite material cannot be afforded by any branch of physical science which remains rigidly consistent with its own postulates. The nature of the interests in response to which the concept of the physical order was constructed[constructed], as we saw, required that the physical order should be thought of and described in terms of rigid mechanism. Hence no science which describes the processes of human life in purely physical terminology can indicate their purposive or teleological character in its descriptions. The purposive character of human conduct, if recognised at all in our descriptions, must find its recognition in that science which describes the aspect of human experience that is in principle excluded from the physical order. In other words, it is Psychology to which we have to go for such a general abstract conception of teleological unity as is necessary for the purposes of the more concrete sciences of Ethics and History.
This function of Psychology is indeed quite familiar to the student of the moral and historical sciences. In Ethics, as Professor Sidgwick has observed, the whole vocabulary used to characterise human conduct, apart from the specially ethical predicates of worth, is purely psychological. All the material which Ethics pronounces “good” or “bad,” “right” or “wrong”—“acts,” “feelings,” “tempers,” “desire,” etc.,—it has taken over bodily from Psychology. And so, too, History would have nothing left to appreciate if a record of merely physical movements were substituted for accounts of events which imply at every turn the psychological categories of “desire,” “purpose,” “intention,” “temptation,” and the rest. Universally, we may say all the teleological categories of human thought on examination prove to be either avowedly the property of Psychology, or, as is the case with the concepts of biological evolutionism, thinly disguised borrowings from it.
If this is so, we seem to be justified in drawing certain important inferences. (1) It will follow that of the two distinct offices which Psychology at present fulfils, one belongs to it, so to say, in its own right and inalienably, while the other is exercised by it temporarily, pending the majority of Cerebral Physiology. While, as we have seen, those parts of psychological doctrine which are concerned with the more mechanical aspects of conduct may ultimately be replaced by Physiology, the parts which deal with the initiation of fresh purposive adjustments, such as the psychology of attention and of feeling, are in principle irreducible to Physiology, and must retain a permanent value so long as mankind continues to be interested in the ethical and historical appreciation of human life.[[171]]