function of the median descending part of the temporal lobes, that taste is probably correlated with the processes of the lower temporal regions, that tactual sensibility is intimately connected with the physiological processes of the motor zone; and the recent researches of Bianchi and Flechsig tend to correlate the highest psychic activity of man with the function of definite areas in the cortex.
Should we care to look for more proofs as to the validity of correlation of psychic with neural, or physical processes, we can also find it in another branch of experimental physiology, namely, physiological psychology. Thus Doctor Lombard by placing sensitive thermometers and electric piles against the scalp noted a rise in temperature during intellectual effort, such as calculation, recitation, composition. The temperature showed a marked rise exceeding 1° F. during an intense emotion. When intellectual activity rose in intensity there was also a parallel rise in temperature, thus the temperature was found to be higher, when poetry was recited silently than when the same was done aloud. Similar results were arrived at by Schiff in his experiments on dogs. He placed thermo-electric needles on the scalps of dogs; the sensations of the animals were then tested with different kinds of stimuli. It was found that whenever the stimulus was given and the sensation experienced, that a change was at once manifested in the cerebral and motor processes which was indicated by the deflection of the galvanometer. When the dog was lying motionless and a rolled up piece of paper was given to him, the galvanic deflection was small, when, however, a piece of meat was brought near the dog, the deflection became considerable. Galvanometric deflections concomitant with psychomotor activities have also been shown in the case of human subjects.
The ponograph is well adapted to demonstrate in a striking way to the doubting layman the intimate relation of physical and mental phenomena. The subject is put on a table, which is so delicately balanced that at the slightest alteration in the distribution of the weight of the subject, it tilts. Now it is found that when the subject is spoken to, or when making some intellectual effort, the table at once tilts possibly because of the increased blood supply to the brain and more especially on account of the motor reactions. Pneumographic, plethysmographic, carotido-graphic, cardiographic, automatographic, ponographic, and ergographic tracings show physiological changes concomitant with the slightest modification of psychic processes. As simple an instrument as the sphygmo-graph can demonstrate the same truth. A sphygmogram taken under mental activity differs from the one taken under mental repose.
All these facts, and many more could be adduced to establish on a firm basis the psycho-physiological hypothesis that psychic phenomena are accompanied with physiological or physical processes. The whole of recent psycho-physiological research work is based on the hypothesis that there is no psychosis without neurosis. The two are concomitant. Psychic and physical phenomena go hand in hand, the two processes run parallel to each other. Thus we find that psycho-physiological parallelism is a strictly scientific hypothesis.
The psychic and physiological series of changes are concomitant, parallel, but they do not stand to each other in relation of antecedent and consequent, they are not causally related. I take here the opportunity of emphasizing the non-causal relation of mental and physiological processes. It is usually taken for granted by many medical men, and even by some scientists, neurologists, physiologists, biologists, who do not happen to think out clearly the more theoretical aspects of their investigations, that brain processes are the direct cause of mental phenomena and that psychology therefore is nothing but a chapter in physiology. Study the brain and you will know all about psychic life. This view is certainly fallacious. A psychic fact as we have pointed out is radically different, different in kind from a physical, mechanical fact. One cannot, therefore, give rise to the other.
The reason why it is thought that physical processes give rise to mental, lies in the fallacious analogy taken from the law of convertibility and equivalence of energy in the activity of physical processes. Heat, it is reasoned, can be converted into electricity, electricity into magnetism, magnetism into motion, motion into sound or light, and the same may be done in reverse order; the energy of physiological processes therefore is converted into mental, or psychic energy. The whole reasoning is wrong. We must remember that what underlies all these different physical phenomena is various forms of molecular and molar motion, and when one order of physical phenomena passes into another, it is after all only the transformation of one form of motion into another form. Quite different is it in the case of the phenomena of consciousness. The activity of consciousness is not a form of motion, and the two therefore, cannot be converted into each other. Mental activity is but figuratively termed energy, just as a well reasoned argument may be characterized as clear and lucid, but it does not mean that one can see a candle shining through it. The energy of mental phenomena is as much the energy of physical and physiological sciences as the idea of a brick is a brick itself and made up of clay.
Furthermore, were it possible that a physiological process should be converted into a mental process, the law of conservation of energy would have to be given up, and along with it the whole edifice of modern science would tumble to the ground. For according to the law of conservation of energy no physical energy can possibly be lost. One form of energy may pass into another, but the physical energy which is some form of motion, molar, molecular, atomic, ionic or electronic cannot be lost, that is, there must always be so much motion, no matter under what form it may appear. Now on the one hand, were it possible that a physiological process, which is nothing but a form of physical energy, could pass into a psychic state, which is no motion at all, we would really have a loss of energy. Were it on the other hand possible that a mental or psychic process should pass into a physiological process, we would have had new energy generated, energy that is not a transformation of some previous existing energy, or physical activity.
If mental and physiological processes were to stand to each other in relation of antecedent and consequent, in relation of cause and effect, we would have had with each beat of consciousness a new creation of physical energy and a loss of it with each cerebral process. This would be sufficient to undermine the basis of science, and .practically we might have had good hopes that in the near future our steam engines would be run by good intentions and windmills by aesthetic feelings.
Psychic and physiological series are no doubt intimately related, but their relation is not causal, they do not stand to each other in relation of invariable succession characteristic of cause and effect, but in that of co-existence. The two series of processes are concomitant, they run parallel to each other, but neither is the cause of the other. A change in the one means also a simultaneous, concomitant modification in the other. In other words, every psychic change must have its physiological concomitant, and vice versa, every physiological process may have its psychic accompaniment. This hypothesis of psycho-physical parallelism is at the basis of all modern psycho-physiological, neurological, and psycho-pathological investigation, inasmuch as it is taken for granted that for every manifested sensori-motor or ideo-motor "symptom" there must be present term for term some physiological process. Psychology takes the same view and accepts the same hypothesis; it does not trouble itself in the least with the philosophical problem as to whether the two series of phenomena, the mental and the physical, have behind them separate substances, or whether they are but two different aspects of the same thing. This belongs to metaphysics. The psycho-physiological theory like all other scientific hypotheses has nothing to do with metaphysical substrata, but deals only with facts and their relations.
XIII The Deductive Basis of the Positive Psychological Hypothesis
The concept of causality cannot be worked in psychology in the same way as it can be done in the physical science. The circle of physical processes is complete in itself. A physical process without ceasing to be physical can be traced endlessly in the past or future, all the links of the endless process must all be physical in their nature. For if we permit in the endless chain of links of the physical process any other but physical links to be interpolated, all the
