The Foundations of Normal and Abnormal Psychology/Part 1/I
We assume that the reader regards psychology as a science. It is however one thing to label a subject as a science and another thing to understand clearly in what sense the term science is used in the case of psychology. A clear understanding of the nature of science is here of special importance on account of the peculiar position psychology occupies in the hierarchy of human knowledge. It is therefore desirable to define the meaning of science before we proceed to discuss the subject matter of psychology.
Science is the description of phenomena and the formulation of their relations. Science describes facts and formulates their relations in laws. The task of science is first to formulate facts belonging to the same type, and then to generalize them, that is to express their general relationship by one comprehensive formula, in spite of the many individual variations in the phenomena. Thus in geometry, possibly the most ancient of all sciences, many isolated and important facts were already known to the semi-civilized nations of antiquity, but it required the rationalizing spirit of the Greek mind to classify and generalize the facts into theorems, the laws of space. Many important properties of the right-angled triangle, for instance, were already known to the ancient Chaldeans and Egyptians. They knew that if in a right-angled triangle the two sides are respectively three and four, the hypotenuse must be five and so on; that is, they knew only concrete facts, but what they lacked was just the scientific side. It required a Pythagoras to discover that in all right-angled triangles the sum of the squares of the two sides is equal to the square of the third. No matter what the size of the triangle be, no matter how different in length its sides are, once the triangle be of the same type, namely right-angular, the same general relationship must obtain.
To take an illustration from physics. Falling bodies form one type of movement. Now the bodies themselves may be different in kind, in nature, may be of various material, may differ widely in structure, weight, and shape, and still, since they all belong to the same type of motion, they are, in spite of their manifold diversity, expressed in one general formula, in one law, namely, that the spaces traversed are proportional to the square of times.
In other less exact sciences the facts are exhaustively described and a general statement is formulated as to their relationship. In physiology, for instance, we find mainly descriptions of facts classified into types, the relationships of which are expressed in general formulae, or laws. Thus in the cerebro-spinal nervous system, each part and its functions are described as fully as possible, and then all the facts are brought under one comprehensive formula such as the reflex arc. In embryology the different changes of the embryo are minutely described, classified into types, into a certain number of definite stages, and then all the changes, in the infinite wealth of their variety, are expressed in the general proposition that the embryo in the short period of its development traverses in an abbreviated form all the stages that the species has passed through in the many ages of its existence; all the changes are generalized in the formula that the ontogenetic series is an epitome of phylogenetic evolution. We may, therefore, say that science is a description of types of facts, the relationships of which are expressed in general comprehensive formulae, or laws. It is in this sense that we understand psychology to be a science; it classifies phenomena into types and searches for the general expression of their relations, or for what is termed psychological laws.
We must come to something more precise and definite. We said that psychology deals with classification and generalizations of phenomena; but what are these phenomena? In the different branches of science, we find that each one has a determinate order of phenomena to deal with, a definite subject matter. Thus geometry deals with spatial facts, mechanics with motion, physics with changes of molecular aggregations, chemistry with atomic combinations and their mutations, physiology with processes going to make the equilibrium of organic life, sociology with phenomena of social life, and so it is in the case of all other sciences. Now what is the subject matter of psychology? What are the facts, the phenomena with which psychology deals? Psychology deals with facts of consciousness.
On the very threshold of our discussion, we may be stopped by the pertinent question: "You say that psychology deals with facts of consciousness, but what is consciousness?" Consciousness is subjective facts, such as the elements of sensation, feelings, pains, thoughts, acts of willing and the like. Positive science must have given facts, data to work upon; these data it analyzes, describes, classifies into types and seeks to find the formulae of their relationships. Psychology can accomplish no more than any other science. The data of psychology are facts of consciousness, these facts are analyzed into their simplest elements, and the laws of their relations are searched for. But psychology does not, and legitimately cannot possibly go beyond consciousness. Consciousness is the ultimate datum which psychology must assume as given and which is from a psychological standpoint unanalyzable. Consciousness must be postulated, if we wish to enter the temple of psychology.
In this relation psychology is as positive as the rest of her sister sciences. Geometry, a science to which no one will deny exactness, deals as we know with the laws of space-relations. Should we ask the geometrician the same question just put to the psychologist: You say that your science, geometry, deals with facts of space and their relations, but what is space? The geometrician will smile at us. He will tell us that by space he means such forms as lines, angles, triangles, quadrilaterals, circles, cubes, cylinders, pyramids, etc. Should we persist and ask further, "Yes, that is true, but all these are so many forms of space, what is the space itself with which you deal?" The geometrician will no doubt answer: "My dear sir, geometry deals with facts of space, space itself is taken as an ultimate datum. The work of geometry is not to ask what space is in itself, but what the relations are of spatial forms, space itself being postulated."
Mechanics deals with the laws of energy and motion, physics with molecular changes of matter, but neither physics nor mechanics would have gone far, had they stopped to answer the questions as to what motion, energy, matter are in themselves. These are simply postulated, taken for granted, they are the ultimate data of these sciences. In this respect psychology does not differ from other sciences, it takes its subject matter as given and does not inquire as to what the nature of the material is in itself. The reader must remember that the question as to what things are in themselves is not at all a question of positive sciences, but of metaphysics. I do not mean in any way to detract from the dignity of metaphysics, what I wish is simply to point out the limits of positive science. The problem as to what things are in themselves does not fall within the province of science, but within the domain of metaphysical research.
The question as to the nature of consciousness, what it is in itself, may be a very important one, but it lies outside the ken of psychology, just as the laws of aesthetics do not concern the chemist, although the latter may be a great lover of beauty. In the contemplation and enjoyment of a beautiful picture he will not introduce a chemical formula, and in his chemical experiments he will not introduce aesthetic considerations. The same holds true in the case of psychology. The psychologist may be a metaphysician, but in his psychological work he must keep clear of metaphysics. Consciousness therefore is a presupposition, a postulate of psychology.
There is one more important assumption which psychology must start with in order to be a positive science at all, namely, uniformity. Under similar conditions like results follow. Suppose a geometrician should prove to you that the sum of the three angles of a triangle is equal to two right angles, suppose that some sceptic should come in and say, "Yes, that is all right in relation to the triangles in this particular space, in another portion of space, on some other star, or planet the theorem will not hold good." The only answer the geometrician could give is that we must assume that space is uniform, so that wherever we form our triangles we obtain the same results. The same is true in mechanics. The laws of motion and inertia hold good of the pebble on the roadside, of the dust grains dancing in the sunbeam, and of distant stars in the milky way. Uniformity of relations among phenomena must be postulated, if science is to be at all. If under the same conditions different results follow, science would have been an impossibility. Uniformity of nature is one of the most fundamental postulates of science. Psychology assumes uniformity; it assumes that there exist constant uniform types of mental activity with definite relations that can be formulated into psychological laws. Thus psychology at the very outset postulates consciousness and uniformity of mental phenomena.
We can now see in what relation psychology which deals with phenomena of consciousness differs from philosophy whose subject matter is also consciousness. Philosophy has no postulates, psychology, like all other sciences, must have its postulates which it cannot transcend. Philosophy deals with the ultimate in consciousness, it investigates the very postulates of conscious activity. Psychology on the contrary accepts the facts of consciousness as ultimate data.