It is necessary that we should clearly understand what is meant by the psychological conception of mental disorder, the relation it bears to the physiological conception, and the nature of its aims and methods. The consideration of these problems involves some preliminary acquaintance with the fundamental propositions upon which modern science is based, and inevitably leads to questions which are, strictly speaking, beyond the limits of our subject. But as no clear thinking in psychology is possible unless precise notions about these elementary matters have been previously acquired, we may perhaps be pardoned for temporarily trespassing upon the domain of philosophy.

It has been pointed out that modern science is attacking the problem of mental disorder along two different routes. The psychological conception treats the phenomena as states of mind, whereas the physiological conception treats them merely as manifestations of changes occurring in the brain. Now in this statement we are confronted with certain terms which, although loosely and erroneously used in ordinary language, have nevertheless a precise and definite signification. These terms are ‘science’, ‘mind’, ‘brain’, ‘physiology’, and ‘psychology’.

Everybody is aware that science is a method of acquiring knowledge, but everybody is not aware that this method is always one and the same, whatever the subject may be to which it is being applied. The scientist who devotes himself to psychology proceeds in exactly the same manner as the scientist who devotes himself to chemistry.

This introduction seeks to put before the reader a general sketch of the history of psychopathology from its beginnings to the position which it held in 1912, in order that he may be able to appreciate the place in the subject of the principles described in this book. It therefore attempts to cover a wider field than is proper to an introduction, and for this reason the uninstructed layman will probably find it more intelligible and useful if it is read after rather than before the book.

DEVELOPMENT OF PSYGHOPATHOLOGY PRIOR TO JANET

Psychopathology, the science which attempts to explain the problems of mental disorder by psychological principles and laws, is of comparatively recent growth, and can hardly be said to have existed before the last quarter of the nineteenth century. The remarkable phenomena produced by Mesmer and the other ‘magnetisers’ had aroused a widespread interest a hundred years earlier, and later investigators had demonstrated that these phenomena were due, not to the magnets, but to the suggestions communicated by the operator. These ‘suggestions’ were clearly causes of a psychological order, and it was therefore known that psychological causes were capable of bringing about definite changes in mind and body. Until the time of Gharcot (1825–93), however, this conception had not been applied to the problem of disease, and we owe to that investigator the first formulation of the view that certain disorders were due simply to the action of ‘ideas’.

This book lays no claim to be a comprehensive treatise upon the psychology of insanity. The number of independent schools of thought existing at the present day, and the fundamental divergence in their methods of investigation, make it obviously impossible to compress such a treatise into the limits of a small volume. All that has been attempted here is the presentation of certain recent developments in abnormal psychology which have already yielded results of fundamental importance, and which seem to offer an exceptionally promising field for further investigation.

An endeavour has been made to develop the subject-matter of the book in a systematic manner, so that the general principles which it is sought to establish may appear in as clear a light as possible. The adoption of the systematic method in a work of this size, however, renders a somewhat dogmatic mode of presentation inevitable. It is necessary, therefore, to warn the reader that many of the theories to which he will be introduced have not as yet been firmly established, and that they are to be regarded rather as suggestive hypotheses which will ultimately require considerable alteration and improvement.

It must be clearly understood, moreover, that no attempt has been made to cover the whole field of insanity. On the contrary, certain sections of that field have been more or less arbitrarily selected, mainly on the ground that they yield fruitful results to psychological methods of investigation.

In the preceding chapter the phenomena produced by the repression of a complex were divided into two groups, those due to the indirect expression of the complex itself, and those due to the presence of a resistance or censure which prevents the complex exercising its normal direct effect. In all the examples hitherto considered the symptoms present could without much difficulty be assigned to one or other of these two groups. It will nevertheless be obvious that this distinction is largely artificial, and that in the formation of each symptom the factors of indirect expression and resistance both take part. The symptoms may be regarded, in fact, as a compromise between the two factors in question. The complex struggles to express itself, while the resistance endeavours to prevent it achieving its end. The symptom is finally evolved as a compromise between the two opposing forces. In each of the examples cited in the last chapter, however, one of the two components seemed to play a preponderating part in the compromise produced, so that the symptom could be classified as belonging to the corresponding group.

The group of symptoms to which we must now direct our attention, those due to the mechanism of ‘projection’, exhibit this preponderance of one component to a less marked degree, and the phenomena belonging to it are best regarded as instances of compromise formation in which the parts played by the two opposing forces are approximately equal.

In the preceding chapter we have collected together certain of the more prominent phenomena of mental disorder. To the uninitiated eye they appear as a chaos of disconnected facts, each seemingly independent of all the rest. A careful examination will show, however, that there are certain general attributes common to many of the symptoms displayed by our patients. With the aid of these general attributes it is possible to classify the phenomena into groups, and thereby to reduce the confusion to some sort of order.

Firstly, the conditions described as mental deficiency and dementia may be placed in a separate group. They depend, as we have seen, upon an absolute quantitative defect of mental capacity, and are in this respect fundamentally different from all the other phenomena dealt with in chapter III. These conditions are generally accompanied by a correlated defect in the structure of the brain, and it must be frankly confessed that, in the present state of knowledge, the psychological conception is of relatively little value in the study of their causation, and that the physiological conception is a far more profitable instrument of investigation. It is true, of course, that psychology is compelled to take account of such quantitative defects of mental capacity, and that it is able to explain the relation which they bear to many of the other phenomena of insanity, but the questions involved are complicated and difficult, and cannot be satisfactorily considered without presupposing a considerable practical acquaintance with the subject.

In chapter III we have described some of the phenomena to be observed in various morbid states of mind, and in chapter IV we have endeavoured to arrange these phenomena into groups. This process of classification has enabled us to reduce the original chaos into some sort of order, and to obtain a comprehensive view of the facts of our subject. We have discovered, for example, that many of the manifestations of mental disorder are to be regarded as cases of dissociation of consciousness—the stream of consciousness is divided into independent currents no longer combined into one harmonious whole. So far, however, no attempt has been made to explain why these phenomena occur. We have seen that the imaginary voices which torture the hallucinated patient are nothing but split-off portions of his own consciousness, but we have assigned no reason to account for a portion of consciousness being split off in this abnormal manner, nor have we explained why the hallucinatory voice should make remarks of one character rather than another. We have found, in fact, that certain events occur, but we are still altogether in the dark as to why they occur.

The reader who has clearly understood the general principles enunciated in chapter II will at once perceive that we have carried out the first two steps of the method of science, but have as yet made no attempt to proceed to the third step.