Now if there is one feature which is essentially characteristic of the popular conception of the influence of mind in the conduct of affairs it is that consciousness, as controlling, stands in some way apart from the organic happenings over which its control is exercised. How far, we may ask, and in what sense is this popular conception valid? Take any simple case of accomodation to circumstances as the result of the teachings of previous experience let us say the avoidance of nauseous insects by young birds. Naturalism contends that the experience is the concomitant or accompaniment of certain physiological processes in nerve-tissue. Assume, then, that this conscious experience is the concomitant of the nervous processes involved in the instinctive procedure as such. How can that which is a mere accompaniment in any way augment, inhibit, or modify that which it accompanies? How can it be more than an epiphenomenon? It seems to me that, on this assumption, intelligent guidance through the teachings of experience is, for naturalism, simply incomprehensible. But there is an alternative hypothesis open to naturalism. Still holding firmly to its doctrine that mental states and physiological processes in nerve-tissue are concomitant, it may contend that the organ of experience is differentiated from the organ primarily concerned in instinctive behaviour. It is true that biologically we have to deal with what appears to be a single and continuous organ—the brain and spinal cord. But there are no established facts in physiology which prevent our accepting the doctrine that within that organ a control system, which is the physiological embodiment of what for the student of mental science is experience, has been differentiated from the centres concerned in instinctive behaviour, and thus, in a sense, stands apart from the organic happenings over which its guidance is exercised. For naturalism this differentiation is, I conceive, the essential condition of the rise and growth of intelligence as a factor in the upward progress of animal life.
It is not necessary to enter in any detail into the more distinctively biological aspect of the study of instinct. From our present point of view the distinguishing feature of instinctive procedure lies in the fact that the behaviour thus characterised is, on its initial occurrence, prior to and independent of individual experience. It wholly depends, as such, upon how the automatic centres have been built through heredity, and this in turn depends upon what I have spoken of as "survival value" under natural selection. But the automatic centres are in closest possible touch with the differentiated control system which is the organ of experience. And the performance of an instinctive act so stimulates the centres of intelligent control as to afford the primary data of experience. In this sense instinctive behaviour is probably accompanied by vivid consciousness. And from the standpoint of genetic psychology it appears to me that the really important contribution which the study of instinct offers for our consideration is this: that in any given case of hereditary behaviour what we may term an instinctive situation is presented to consciousness, as, for the individual, a primary unit-complex of experience, and that, as such, it is developed independently of any guidance in terms of experience. By the situation as presented to the environing consciousness I understand the whole of the initial stimulation, including both external and internal factors, such as the sight of food on the one hand, and hunger on the other hand; the net results of the behaviour as the situation develops; for example, the seizing and swallowing of food, and the satisfaction or dissatisfaction which is attached thereto. Psychologists analyse the instinctive situation. But I conceive that it is presented to consciousness as one developing whole. And the mode of its development is an organic legacy; it is essentially a flow of physiological process in the automatic centres; but it entails a flow of consciousness in the differentiated centres of intelligent control; and this flow of consciousness in its entirety, within a given situation, I am disposed to regard as a primary datum in individual development.
One of the most perplexing and refractory problems which the earlier psychology essayed to solve is by what process of coalescence and elaboration isolated sensations could build themselves up into the complex wholes of perception, and how these could relate themselves with the similarly-built complex wholes presented to consciousness when active movements were carried out. It assumed that the several sensations which may be distinguished through the application of a difficult and prolonged process of analysis and abstraction, were independent psychological units separately given, and sought to render an account of the manner in which these mental elements threaded themselves on the strands of association. A biological treatment has more and more clearly tended to emphasise the fact that the individual organism comes into the world as a going concern, the recipient of groups of stimuli giving psychological net results on the one hand, and capable on the other hand, on purely organic grounds, of complex modes of behaviour which supply also their net results, the two sets of net results coalescing so as to constitute felt unity-wholes. It has thus tended to relegate many of the problems of mental development to biology, and has come to regard association itself as in large degree dependent on factors which are primarily organic and physiological On this view, then, instinctive procedure—using this phrase in a broad sense to cover all more or less complex hereditary and automatic responses—presents to experience, embodied in the centres of intelligent control, ready-made situations. That is the first act of the mental drama in individual life. Later acts may be more or less under the guidance of experience; for on the subsequent occurrence of like situations, under substantially similar circumstances, these are dealt with in accordance with the meaning which their predecessors had acquired.