§ 3. Associationism.—Faculty Psychology is valuable, if at all, only as a scheme of classification. But the ultimate aim of science is to explain and not merely to classify. Hence, when once explanatory principles came to be clearly conceived and expounded the Faculty Psychology tended to disappear. Its greatest enemy in modern times has been the theory of reproduction as determined by Association. This theory, when pushed to an extreme, so as to exclude all other modes of explanation, becomes what is called "Associationism." Such writers as James Mill in England, and in a very different way Herbart in Germany, may be taken as types of it. The assumption which lies at the basis of Associationism is that mental conditions can only give rise to a mental product, if and so far as they reappear in the product as its components. From this point of view, to explain the origin of a state of consciousness is to enumerate its constituent parts and show how they came to cohere with each other by association. As all words are put together out of the letters of the alphabet, so all derivative mental states and processes are put together out of primary and simple modes of consciousness, arising from the stimulation of sensitive surfaces either outside or inside the body. In ordinary human consciousness these elementary sensations rarely if ever occur in their purity. They have all acquired associations, so that they now appear embedded in a cluster of revived residua of previous experiences. Thus, when an orange is perceived, what is immediately given in the way of sensation may be only yellow colour. According to the theory we are considering, the perception of the orange wholly consists in the more or less complete reinstatement of past sensations by the present sensation. The present sensation forms the nucleus of a cluster of revivals. The immediate ocular experience reproduces the visual appearance of the orange from other points of view. It reproduces the smell, and the taste, and the character of the pulpy contents as presented to sight and touch.

It is admitted that for the most part the simple components of such a psychical complex can only be ascertained by laborious investigation; that the ordinary states of consciousness which common sense regards as ultimate are really not ultimate, but have an origin and development due to psychological conditions. The essential point is that these conditions are held to operate only in one special manner; they combine, and their combination is the effect which they produce. On this theory, causation and composition coincide.