BODY AND MIND, in philosophy, the problems of the reality of mind and body, and of the relations conceived to exist between them. Mind and body, positing temporarily their reality, may first be regarded from the point of view of correlated action. Generally experience reveals indisputably the intimate re lation which exists between the constitution and modifications of bodily functions and the char acter and alterations of consciousness. Con sider the following: the dependence of certain forms of consciousness upon the functioning of the senses; modifications due to injury by a blow, on lesion in the cerebral cortex; effect of loss of sleep upon attention; effect of the use of certain drugs; pleasures and pains re sulting from functioning of sense; feeling of effort which accompanies bodily work; the phe nomena of sleep; diseases of memory and will, double personality; phenomena of hypnotism, hallucination, etc.; the evidence from heredity, sexual differences and other allied phenomena. All these, as facts, afford an indisputable con clusion concerning the correlated action of mind and body.
But difficulties arise as soon as we undertake to state the nature of the relations which exist between them. The general truth which the phenomena referred to appear to establish, that every psychosis has its concomitant neurosis and every neurosis a concomitant psychosis, is not entirely borne out in fact. The former part of the statement is indubitable; the latter by no means so. Mental activity always involves nervous activity, but the nervous system does work other than that connected with mind. Moreover, the precise interconnections of men tal fact with cerebral fact, and vice-versa, is not only not known, but the specific character of the neurosis concomitant with the psychosis is perhaps impossible of final analysis. But until these phenomena are understood, the na ture of the relations of body and mind cannot be finally determined. However, physiological psychology has successfully established certain general conclusions concerning the existence of uniform relations between concomitant psy chical and neural processes. The most obvious of these is the time-order or synchronous occur rence of the two series of events. The remain der are concerned, in the main, with variations of intensity, quality, combination and complex ity. .Qualitative psychical differences, however, are not accompanied by corresponding differ ences of molecular movement. These are quite different from the corresponding sensational differences.
Philosophical systems, from the days of Greek thought (See ANAXAGORAS ; ARISTOTLE) down to the present, have taken up the lem where psychology leaves off. These tems may be divided into dualism and monism.
According to dualism, the first and crudest theory of which was promulgated by Descartes, both mind and body are real existences, and their relations must accordingly be determined. The problem assumes two forms, the epistemo logical and the genetic. According to the for mer of these a knowledge of both body and mind is posited. Various theories concerning .their interaction then arise, such as the causal relation, parallelism, pre-established harmony, and occasionalism. The first of these is not only the most important but the philosophical conceptions concerning it may be said to strike at the inmost heart of the problem and their assumption determine the acceptance or rejec tion of general theories. Physiological psychol ogy has demonstrated the temporal concomi tance of the psychosis with the intermediate central portion of the neurosis. But we have certain neuroses revealing physiological proc esses devoid of conscious concomitant. Now, the question arises: How may this partial parallelism be accounted for? Is there a causal relation such as our initial phenomena seemed to indicate, or have we only the appearance of it in a general parallelism? Science has failed to afford precise answers to these questions. According to it the series of nervous events is complete in itself and self-sufficient. Hence, since antecedent events fully account for con sequent ones, consciousness can have no causal action upon the neural series. Consciousness, then, is a mere accident and without determin ing power in any series. This gives us the doc trine of human automatism, according to which all our nervous actions are determined, and con sciousness is an unnecessary attachment. On the other hand, others regard psychical phe nomena as having a reality equal to that of physiological phenomena. They acknowledge generally the conditioning effect of nervous processes upon mental ones, but they divide again on the question of the reality of causal connection. Finally the genetic view traces its distinction of mind and body upon the dualism which a development theory in general appears to demand; or it accepts it as an hypothesis, uncritically examined, but convenient for prac tical purposes.