depends on the corporeal individual and can only be known from physical, bodily manifestations. Each living being manifests some activity in its reactions to the stimuli of the external environment. Now what are the reactions characteristic of consciousness? Where are the distinctive marks that stamp a physical manifestation with the impress of psychic states? The only sure way to tell is by purposive activity. We know that our neighbor is conscious, because , of his active purposive life. When a fly is on his nose, he raises his hand and brushes it away; he knows how to walk and preserve equilibrium; avoids obstacles; lives in a house for protection from the changes of weather and from harmful intruders; seeks shelter from rain; dresses himself warmly on a frosty winter day; a thousand other movements all of them expressive of purposive activity tell us of our neighbor's consciousness, intelligence. The stone on the road changes its place according to the influences of incident forces; the grain of dust is blown hither and thither by the wind; they do not show a more or less definite purposive activity under changing circumstances. The disturbance of their equilibrium does not stimulate them to induce changes in the external environment, changes that would tend to restore that lost equilibrium: They, therefore, have no purpose. (For a purpose is the tendency to realize some external action which is useful or indispensable to the life-existence of the particular individual being. The tendency to the maintenance of a definite activity in opposition to the onset of disturbing forces of the environment in order to restore the lost equilibrium, may be considered as the universal formula for purposive life in general.
This formula holds true of all animal life. The man in running after the car has purpose, so has the cat in chasing the mouse, so has the deer in fleeing from the hunter. The very amoeba, that lump of protoplasm, in extending its pseudopodia to draw in the bit of nutriment, possesses the germ of purposive activity, and some primitive psychic state must therefore be ascribed to it. Life is essentially purposive in its nature. Wherever, therefore, we meet with life, there some form of psychic state, however primitive and elementary, must be present. Psychic states stand in the most intimate relationship to life activity. The two in fact cannot be separated. Psychosis is concomitant with biosis. Psychologists as well as physiologists all agree thus far, that there is no psychosis without neurosis; some go further and affirm that there is no neurosis without psychosis; I think, we are closer to the truth, if we advance still further and assume, that there is no biosis without psychosis. Psychic states must be predicated not only of highly organized animals, possessed of a nervous system, but also of the most elementary monocellular organisms.
The evolutionist especially must accept our last conclusion, for he will agree that consciousness did not come into existence per saltum, he will acknowledge that the germs of conscious life characteristic of the highest organized being must already be present in the lowest types of life, out of which developed the higher, the more complex organisms.
We are now in a position to define the scope of psychology.
Psychology is the science of psychic states both as to content and form, regarded from an objective standpoint, and brought in relation to the living corporeal individual.
VI The Sources of Psychology
Facts of consciousness, we pointed out, are the subject matter of psychology. The question arises as to the sources of the facts. The botanist, when he wishes to carry out a series of experiments, goes into the herbarium or into the field to gather the material for his study. The entomologist collects his specimens on the street, field, and forest. The same holds true in the case of all other sciences. The external world is infinitely rich, it is an inexhaustible mine from which physical science draws its facts. Now what are the sources of the psychologist? The psychologist cannot possibly go out into the forest, catch his specimens, dry them, and pin them for his observation and study.
This question as to the sources of psychology comes to us with greater force, when we realize that psychological facts are not o! the same order with those of the rest of natural physical sciences. It is, of course, evident that we must draw our material from consciousness, but where shall we turn to find the facts? Where are the particular localities from which we can work out and bring to light mental facts? Such is the difficult question that arises before the mind of the scientist, who has been trained in the school of concrete natural science. He finds himself helpless. The neurologist to whom a psychological training is truly invaluable, finds himself ill at ease when in his investigations he strikes a problem which has to be studied mainly from a psychological point of view. A piece of tissue, a lump of protoplasm, a nerve cell with its dendrons and axons can be stained, mounted, observed, and experimented upon, but who can get hold of a fact of consciousness, of an elementary psychic state, of a sensation, of a feeling, of an idea, stain them, put them under the microscope for scientific investigation? The facts of consciousness are so peculiar, so different in kind from those which form the subject matter of other sciences that they who are trained exclusively in concrete natural sciences are at a loss where to look for "real" psychological facts.
Some even go so far as to doubt whether facts of consciousness are "real" facts at all. Frequently I have heard from people with a good medical education, people who were far from being unintelligent, that they doubted the reality of psychic facts: "they are not anything! nothing substantial!" Comical as this last assertion may appear, one can understand its reason; one can understand the consternation and bewilderment of him who for the first time puts his foot on the threshold of psychology. What they meant to express was the strange experience of having been confronted with facts of a nature totally different from the ones with which they usually dealt. The facts with which they are conversant are of a tangible nature, but the facts of consciousness are not tangible, they cannot be seen, nor tasted, nor smelled, nor weighed by pounds and ounces, nor measured by rulers and compasses. In short, psychological facts cannot be reached by any of the sense organs; that is why they are such a puzzle, that is why some arrive at the conclusion that facts of consciousness can hardly be considered as facts, that they are not anything substantial. Still on further reflection any of these sceptics will admit that the phenomena of consciousness exist, and as such they must be facts. In fact, if one wants to be a thorough sceptic, he may doubt the reality of the external material world. All that might be nothing but a dream, nothing but an illusion, a hallucination. We have no sure criterion of the truth of the external material reality, but one thing remains perfectly clear In all this destructive scepticism and that is the reality of the doubting thought, the existence of the sceptic consciousness. That is why Descartes, the father of modern philosophy, beginning with profound scepticism as to the reality of things finally found his criterion of the truth of real existence in his very doubting thought, and he expressed it in his famous "Cogito ergo sum." Thought, therefore, is even more real than the objects of the material world, we know of the latter only through thought, through consciousness. In short, consciousness is a stern reality, and the phenomena of consciousness are real facts.
We may refer here to the behavior hypothesis recently advanced by Watson. The psychological knowledge of animals can only be obtained from the observation of their action, of their behavior, or of their adaptations to their environment. The same holds true in the case of human psychology. Man does not differ from other animals and should be studied in the same way. This, if I understand Watson aright, is essentially his position. Watson goes to the extent of denying the very existence of "centrally initiated processes," he reduces all psychology to peripherally induced processes, sensory and motor. He contests the presence or the very existence of images and denies the presence of any affective elements. Perhaps it may be best to quote Watson's own words:
"Having thus summarily dismissed the image and the affective elements, I crave permission to restate the essential contention of the behaviorist. It is this: the world of the physicist, the biologist, and the psychologist is the same, a world consisting of objects―their interests center around different objects,
