Now this work of analysis, which we have so far pursued without the aid of any technical method, constitutes the first part of the real problem of psychology. The psychologist is called upon, first of all, to determine the num ber and nature of the mental elements. Mind, like all other organizations,— like the natural world itself,—is built up from certain irre duable elements; and if we are properly to understand it, we must catalogue and describe its elementary processes. Psychologists are nowadays fairly well agreed that the mental elements are of two kinds or classes: sensa tions (blue, gold, sour, tone C, the sensa tions of pressure on the skin, of muscular con traction, of smell, etc.), the ultimate constituents of the intellectual life, and affections (pleasant, unpleasant), the ultimate constituents of the life of feeling and emotion. There is no simple process underlying the volitional life; all acts of will, all resolutions and choices, are made up of sensations and affections in conjunction. On the other hand, mind is not adequately de scribed as a resultant or derivative of the two elements. It is true that every consciousness, in the last resort, is compounded of so many sensations and a certain affection. But we find that the elementary processes of a conscious ness may differ, not only in degree or intensity (as strong and weak, loud and faint), but also in clearness or distinctness. So we may speak of a °state) of consciousness, very much as we speak of the state of the roads, or of the weather or of a man's affairs. We speak always in terms of the same material: in terms of the road-bed, of rain and shine, of capital and in terest. In the case of consciousness, we speak always in terms of the ultimate elements, sen sations and affections. Only, as the road may be firm or muddy, the weather clear or ening, the financial outlook good or bad, so may the processes in consciousness be dear or obscure, distinct or indistinct, powerful and in sistent or ineffective, overshadowed by rival processes. It is worth noting that modern psy chology thus finds a use for the phrase estate of consciousness" which is altogether different frdm its use in the older psychology. When consciousness was identified with the °I," the phenomena that we now call processes of con sciousness were naturally identified with the ((states" or "manifestations') of the active prin ciple; and even to-day, in popular writing, the phrase "states of consciousness" is oftentimes employed with the meaning of "conscious proc esses." Such confusion of language can only minister to confusion of thought. The processes, the materials of consciousness, are one thing; the state or condition in which the materials are presented is another.
The most important states of consciousness, in the normal life, are those of attention and inattention. In attention, the processes that make up a consciousness run their course at two different levels. The processes attended to are more clear and distinct, sometimes are stronger and last longer than their fellows; the processes attended-from are depressed, checked, obscured. In inattention, all the processes run at the same low level.
Analysis, then, the first part of the problem of psychology, leaves us with the two elemen tary processes, sensation and affection, and with the elementary states of attention and inat tention. The psychologist is next required to bring the results of his analysis together, to make a synthesis, to formulate laws of the con nection of the elements. The synthesis is tested, at every step, by appeal to introspection, that is, to the actual facts of mental experience. If the analysis has been faulty, the reconstruction will be faulty, will not square with the facts; the method thus becomes its own test of truth. Proceeding in this way, psychology is able to rise to laws or uniformities; it states the laws of color mixture, the laws of affective sequence and composition, the limits of the grasp and duration of attention. Proceeding still further
along the same road, it states the laws of the association of ideas, or of the expression of the emotions. In time, it becomes quantitative, and gives numerical formulae for the intensity of a color contrast or the trustworthiness of mem ory. In doing all this, it is simply following the example of the sciences of nature, organiz ing and systematizing its material.
If, now, psychology went no farther, it would still have claims to rank as a science. But it would be a merely descriptive, not an explana tory, science. As a matter of fact, it goes on to explan its phenomena, to give the conditions under which they occur or appear. And at this point' we come upon one of those theoretical differences of which we spoke above. What are the conditions of a mental process? Some psychologists affirm that, as the mind is always found together with a living body, so it is always conditioned upon physiological proc esses; a mental formation of concretion is to be explained by reference to the bodily condi tion that underlies it. Others, again, make ap peal to unconscious or subliminal mental proc esses, which are the condition of our conscious experience, of the supraliminal mind. And yet others would explain mind by mind, deriving mental process from mental process by a prin ciple of mental causality. We cannot decide between these suggestions; limits of space for bid us even tove an adequate account of them. It may be that the second is the least satisfactory of the three, while controversy is keenly concerned about the other two. The experimental psychologists tend, perhaps, rather toward the first than the last.
The Method of The special method of psychology is experimental intro spection. Two questions arise with regard to i it: Is introspective observation ever really valid? And is the experimental method ade quate to the whole mind, or only to its simpler processes? It has been objected that introspection can never yield valid results, for the simple reason that it interferes with the course of conscious ness. If consciousness is made up of mental processes, then introspection itself is a process or a group of processes. Hence, whenever I set out to observe a given complex, I introduce into consciousness (by the mere fact of obser vation) another complex, which must clash with the object of my observation. But this is a poor method which interferes with the very thing which it purports to examine and de scribe! The objection is usually met by the rule that one must wait to observe a mental process until after it has completed its passage; that introspective examination must always be a Post mortem examination. On this rule, every introspection would involve memory, and be subject to the errors to which memory is subject; though the memory is in play so soon after the event to be remembered that these errors may be considered minimal. In reality, both the objection and its answer seem to beg the question of what introspection is. What the psychologist does, when he introspects, is to experience attentively, to live attentively, the process under and to make a report about his experience in words. No new process is introduced into consciousness. Whether the words that describe the experience are uttered as the process runs its course, or are pronounced after it is over, will depend upon the circumstances of observation and upon the psychologist's ability and training: no single rule can be laid down in the matter. As thus understood, there can be no question but that introspection is a valid form of scientific observation. And even apart from this theo retical justification, introspection is justified by its results.