1.. The view that psychology is an empirical science which deals, not with a limited group of specific contents of experience, but with the immediate contents of all experience, is of recent origin. It encounters even in the science of today hostile views, which are to be looked upon, in general, as the survivals of earlier stages of development, and which are in turn arrayed against one another according to their attitudes on the question of the relations of psychology to philosophy and to the other sciences.
On the basis of the two definitions mentioned above (sec.1, 1) as being the most widely accepted, two chief forms of psychology may be distinguished: metaphysical psychology and empirical psychology . Each is further divided into a number of special tendencies.
Metaphysical psychology generally values very little the empirical analysis and causal interpretation of psychical processes. Regarding psychology as a part of philosophical metaphysics, the chief effort of such psychology is directed toward the discovery of a definition of the "nature of mind" which shall be in accord with the metaphysical system to which the particular form of psychology belongs. After a metaphysical concept of mind has thus been established, the attempt is made to deduce from it the actual content of psychical experience. The characteristic which distinguishes metaphysical psychology from empirical psychology, then, is its attempt to deduce psychical processes, not from other psychical processes, but from some substratum entirely unlike these processes themselves: either from the manifestations of a special mindsubstance, or from the attributes and processes of matter. At this point metaphysical psychology branches off in two directions. Spiritualistic psychology considers psychical the manifestations of a specific mindsubstance, which is regarded either as essentially different form matter (dualism), or as related in nature to matter ( monism or monadalogy ). The fundamental metaphysical doctrine of spiritualistic psychology is the assumption of the supersensible nature of mind, and in connection with this, the assumption of its immortality. Sometimes the further notion of preexistence is also added. Materialistic psychology, on the other hand refers psychical processes to the same material substratum as that which natural science employs for the hypothetical explanation of natural phenomena.
According to this view, psychical processes, like physical vital processes, are connected with certain organizations of material particles which are formed during the life of the individual and broken up at the end of that life. The metaphysical character of this form of psychology is determined by its denial that the mind is supersensible in its nature as is asserted by spiritualistic psychology. Both theories have this in common, that they seek not to interpret psychical experience from experience itself, but to derive it from presuppositions about hypothetical processes in a metaphysical substratum.
2. From the strife that followed these attempts at metaphysical explanation, empirical psychology arose. Wherever empirical psychology is consistently carried out, it strives either to arrange psychical processes under general concepts derived directly from the interconnection of these processes themselves, or it begins with certain, as a rule simpler processes, and then explains the more complicated as the result of the interaction of those with which it started. There may be various fun-damental principles for such an empirical interpretation, and thus it becomes possible to distinguish several varieties of empirical psychology. In general, these may be classified according to two principles of division. The first has reference to the relation of inner and outer experience and to the attitude which the two empirical sciences, natural science and psychology, take toward each other. The second had reference to the facts or concepts derived from these facts, which are used for the interpretation of psychical processes.
Every system of empirical psychology takes its place under both of these principles of classification.
3. On the general question as to the nature of psychical experience the two views already mentioned. (sec. 1) on account of their decisive significance in determining the problem of psychology: psychology of hte inner sense, and psychology as the science of immediate experience .
The first treats psychical processes as contents of a sphere of experience coordinate with the sphere of experiences which, derived through the outer senses, is assigned as the province of the natural sciences, but though coordinate is totally different from it. The second recognizes no real difference between inner and outer experience, but finds the distinction only in the different points of view from which unitary experience is considered in the two cases.
The first of these two varieties of empirical psychology is the older.
It arose primarily through the effort to establish the independence of psychical observation in opposition to the encroachments of natural philosophy.
In thus coordinating natural science and psychology, it sees the justification for the equal recognition of both spheres of science in the fact that they have entirely different objects and modes of perceiving these objects.