Page:Philosophical Review Volume 1.djvu/396

380 to act in response to feelings or desires, there is also the power to inhibit or restrain action, notwithstanding the tendency of feelings or desires to manifest themselves in active motor outbursts." The significance of this statement lies in the admission of an additional power of the mind besides the type of reflex action, and one which is opposed to it. This characteristic of it is conceded by Spencer, Bain, Ribot, and most writers who have discussed it. Special illustrations of inhibition are found in such cases as the delay or stoppage of the heart-beat by disturbances in the vagus nerve of the heart, or in the restraint by the brain of certain muscular movements mediated by the spinal cord. These are instances familiar to the special student of physiology. More common instances are such as modifying one's movements by some unexpected or additional impression, mitigating pain by some new sensory stimulus, suppressing one motive to act by another and opposing motive. If a child be engaged in active muscular exertion and be suddenly disturbed by a new object in the field of consciousness, it may cease at once from its exercise. The new impression is said to inhibit the motor action going on at the time.

Some of these forms of inhibition, into a detailed description of which we cannot enter, are peculiar to the nervous system and take place without any reference to consciousness. This is only to say with most writers that an inhibitive as well as impulsive power is a characteristic of nervous organisms. The phenomenon will perhaps be explained in several ways which leave no room for supposing the relevancy of the fact in regard to the problem of freedom. For instance it may be said that the amount of force which the system is capable of expending is a fixed sum, and that when it is occupied in any given direction a disturbance from any other direction will naturally absorb enough interest or energy to make the sum of both activities equal to the total of the fixed possible force or equal to that which was inhibited. This is probably the case. But the fact has no bearing upon the point which we are raising. It is that an action, which ought to be the same according to all mechanical laws, is modified or even prevented by an influence which,