The logical distinction, which practically amounts to a separation between imagery and meaning, is the counterpart of the psychological distinction between stimulus and response, between the two poles of sensori-motor activity, where the stimulus is defined in consciousness in the form of imagery, in the form of sense-qualities centrally excited, and where the response is directed and controlled _via_ this imagery, so as to function in bringing some end, project, purpose, or ideal, nearer to realization, some problem nearer to solution.
Psychologically, there is no break between image and response, between thought and action. The stimulus is a condition of action, in both senses of the ambiguity of the word "condition." (1) It _is_ action; it is a state or condition of action. (2) It is also an initiation of action. _If_ the appropriate stimulus, then the desired action. The response to an image is the meaning of the image. Or, the response to any stimulus _via_ an image--mediated, controlled or directed by an image--is the meaning of that image. The less imagery involved in any response, the greater the presumption in favor of the belief that the response is either an instinctive impulse or else has become a habit of mind, an adequate idea. The reduction and loss of sense-content which an image may undergo--the wearing away of an image, it is sometimes called--is not a sign that this sense-content has no logical function; but rather that it has fulfilled a logical function so well that it has made part of itself useless. The husk, to recall one of Mr. Bradley's comparisons, that useless husk, tends to fall away, to lapse from consciousness, after it has served the purpose of helping to bring the kernel of truth to fruition.
This raises again the original question as to whether the sense-content, the quality, the existential quality, of an image has a logical function. I will ask first whether it has a function from the standpoint of psychology. We will agree with the empiricist that the content of an image is representative, that it is a return, a revival, of a sense-content previously experienced through the activity of sense-organs stimulated from the periphery. What is the function, then, of the representative image? Sensation, quality, as we have implied above, is the stimulus come to consciousness. To explain how a stimulus can "come" to consciousness is a problem I will not attempt to go into here. I assume as a fact that there are times when we know what we are about; when we are conscious of the stimuli, or conditions of action, which are tending in this direction or in that, and when through this consciousness we exercise a controlling influence over action by selecting and reinforcing certain stimuli and suppressing or inhibiting others. It is true that we do not always realize to how great an extent our actions are controlled by stimuli which do not come to consciousness, by reflexes, instincts, and habits which do not rise above the threshold of imagery. And when this vast complex of hidden machinery is partly revealed to us, it may either cause the beholder to take a materialistic, mechanical, or fatalistic view of existence, to say that we are the victims of our own machinery, or else it may induce the other extreme of more or less mystic pronouncements regarding the province of the subconscious, of the subliminal self; thus out of partial views, out of half-truths, metaphysical problems arise and arm for mutual conflict. Nevertheless, there is a presumption, amounting in most minds to a conviction, that we do at times consciously control some of our actions. And it is only making this conviction a little more explicit to say that we consciously control our actions through becoming aware of the stimuli, or conditions of action, and through selecting and reinforcing them.