of science is remodeled more quickly and completely than the map of Asia.
Psychology has never had a well-defined territory. As states of consciousness appear to be less stable and definite than the objects of the material world, so the science of psychology is more shifting in its contents and more uncertain in its methods than any physical science. "We are told indeed in our introductory text-books that psychology is the science of mind and that mind and matter are the most diverse things in the world. It is said further that psychology is a positive science and is thus clearly distinguished from the normative disciplines, such as logic and ethics. Words are also used to set psychology off from sociology, history, philology and the rest. But while all these verbal definitions may satisfy the college sophomore, they must be perplexing to the candidate for the doctor's degree.
The distinction between mind and matter is one of the last words of a philosophy which does not yet exist, rather than an axiom of every-day experience on which preliminary definitions may be based. We can not rest satisfied with an empirical psychology in which the distinction is self-evident, an epistemology in which it is explained and a metaphysics in which it disappears. It may be that we follow Descartes rather than Aristotle in our psychology, not so much from the needs of the science itself as from the demands of the church, on the one hand, and of physical science, on the other. The church required souls that might be saved or damned; physics wanted a world independent of individual perception, and as the methods of exact science were extended to the human body it became a part of the physical system.
To us who have been brought up in the orthodox tradition, the views of some of those who have passed from natural science to metaphysics seem decidedly naive. Thus Mach entitles the concluding section of his Science of Mechanics 'The Relations of Mechanics to Physiology,' when he is discussing not the question as to whether vital phenomena may be reduced to the laws of matter in motion, but the relations between sensations and the physical stimulus. Pearson tells us in his Grammar of Science that if the cortex of one brain were connected with another by a commissure of nerve substance, there would be 'physical verification of other consciousness.' Ostwald lets energy do hermaphroditic service in the physical and the extra-physical households.
But it is not certain that such ingenuous commingling of the mental and the physical worlds is more repugnant to common sense or natural science than the logical subtleties of the schools, which undertake to define, relate or obliterate them. It is generally assumed that a psychologist must be either an interactionist or a parallelist. Ac-