nature, which cannot be reduced, even in part, to other processes. This work is continued, with other conscious- nesses, until he is able to pronounce with some confidence upon the nature and number of the elementary mental processes. Then he proceeds to the task of synthesis. He puts the elements together, under experimental con- ditions: first, perhaps, two elements of the same kind, then more of that kind, then elementary processes of diverse kinds: and he presently discerns that regularity and uniformity of occurrence which we have seen to be characteristic of all human experience. He thus learns to formulate the laws of connection of the elementary mental processes. If sensations of tone occur together, they blend or fuse; if sensations of colour occur side by side, they enhance one another: and all this takes place in a perfectly regular way, so that we can write out laws of tonal fusion and laws of colour contrast.
If, however, we attempted to work out a merely descrip- tive psychology, we should find that there was no hope in it of a true science of mind. A descriptive psychology would stand to scientific psychology very much as the old- fashioned natural histories stand to modern text-books of biology, or as the view of the world which a boy gets from his cabinet of physical experiments stands to the trained physicist's view. It would tell us a good deal about mind; it would include a large body of observed facts, which we might classify and, in large measure, bring under general laws. But there would be no unity or coherence in it; it would lack that single guiding principle which biology has, for instance, in the law of evolution, or physics in the law of the conservation of.energy. In order to make psychology scientific we must not only describe, § 9- The Problem of Psychology 39 we must also explain mind. We must answer the question 'why.'
But here is a difficulty. It is clear that we cannot re- gard one mental process as the cause of another mental process, if only for the reason that, with change of our surroundings, entirely new consciousnesses may be set up. When I visit Athens or Rome for the first time, I have experiences which are due, not to past consciousnesses, but to present stimuli. Nor can we, on the other hand, regard nervous processes as the cause of mental processes. The principle of psychophysical parallelism lays it down that the two sets of events, processes in the nervous system and mental processes, run their course side by side, in exact correspondence but without interference: they are, in ulti- mate fact, two different aspects of the same experience. The one cannot be the cause of the other.
Nevertheless, it is by reference to the body, to the ner- vous system and the organs attached to it, that we explain mental phenomena. The nervous system does not cause, but it does explain mind. It explains mind as the map of a country explains the fragmentary glimpses of hills and rivers and towns that we catch on our journey through it. In a word, reference to the nervous system introduces into psychology just that unity and coherence which a strictly descriptive psychology cannot achieve.
It is worth while, for the sake of clearness, to dwell on this point in more detail. The physical world, the world of inde- pendent experience, just because it is independent of the indi- vidual man, is complete and self-contained. All of the processes that make it up are bound together as cause and effect; nowhere is there a gap or break in their connection. Now, among the processes that make up this independent world are the processes 40 Subject-matter, Method and Problem of Psychology of the nervous system. These are linked, as cause and effect, both to one another and also to physical processes, outside the body, which precede and follow them; they have their fixed place in the unbroken chain of physical events; they may them- selves be explained, exactly as the occurrence of dew is explained. Mental processes, on the other hand, correspond, not to the whole series of physical events, but only to a small part of them, namely, to certain events within the nervous system. It is natural, then, that mental phenomena should appear scrappy, disconnected, unsystematic. It is also natural that we should seek their expla- nation in the nervous processes which run parallel to them, and whose causal connection with all the other processes of the inde- pendent world ensures the continuity that they so conspicuously lack. Mind lapses every night, and reforms every morning; but the bodily processes go on, in sleep and in waking. An idea drops out of memory, to recur, perhaps quite unexpectedly, many years later; but the bodily processes have been going on without interruption. Reference to the body does not add one iota to the data of psychology, to the sum of introspections. It does furnish us with an explanatory principle for psychology; it does enable us to systematise our introspective data. Indeed, if we refuse to explain mind by body, we must accept the one or the other of two, equally unsatisfactory alternatives: we must either rest content with a simple description of mental experience, or must invent an unconscious mind to give coherence and contin- uity to the conscious. Both courses have been tried. But, if we take the first, we never arrive at a science of psychology; and if we take the second, we voluntarily leave the sphere of fact for the sphere of fiction.
These are scientific alternatives. Common sense, also, has in its own fashion realised the situation, and has found its own way out. It is precisely because of the incompleteness and discon- nectedness of mental experience that common sense constructs a hybrid world, travelling easily from mental to physical and back again, filling up the breaks in the mental by material borrowed from the physical. That way, we may be sure, lies confusion of thought. The truth underlying the confusion is, however, the § 9- The Problem of Psychology 41 implicit acknowledgment that the explanatory principle for psy- chology must be looked for beyond, and not within, the world of dependent experience. — Physical science, then, explains by assigning a cause; mental science explains by reference to those nervous processes which correspond with the mental processes that are under observation. We may bring these two modes of explanation together, if we \ define explanation itself as the statement of the proximate cir- cumstances or conditions under which the described phenomenon occurs..Dew is tormed under the condition of a difference of temperature between the air and the ground; ideas are formed under the condition of certain processes in the nervous system. Fundamentally, the object and the manner of explanation, in the two cases, are one and the same.
In fine, just as the method of psychology is, on all essential points, the method of the natural sciences, so is the problem of psychology essentially of the same sort as the problem of physics. The psychologist answers the question ' what ' by analysing mental experience into its elements. He answers the question ' how ' by formulating the laws of connection of these elements. And he answers the question ' why' by explaining mental processes in terms of their parallel processes in the nervous system. His programme need not be carried out in this order: he may get the hint of a law before his analysis is completed, and the discovery of a sense-organ may suggest the occurrence of certain elementary processes before he has found these processes by introspection. The three questions are in- timately related, and an answer to any one helps towards the answers to the other two. The measure of our progress in scientific psychology is our ability to return satisfactory answers to all three.
1 42 Subject-matter, Method and Problem of Psychology References for Further Reading1 § I. Herbert Spencer, The Genesis of Science, in Essays: Scientific, Political and Speculative, ii., 1 891. K. Pearson, The Grammar of Science, 1900, chs. i., iii. §2. O. Kuelpe, Outlines of Psychology, 1909, § 1, 1-7. W. Wundt, Outlines of Psychology, 1907, §§ 1, 2. § 3. G. S. Fullerton, A System of Metaphysics, 1904, chs. i., v. § 4. W. James, Principles of Psychology, i., 1890, 128-144 (for inter- action: read with E. B. Titchener, Were the Earliest Organic Movements Conscious or Unconscious f in Popular Science H. Ebbinghaus, Grundz'uge der Psychologie, I., 1905, § 4 (for parallelism). C. A. Strong, Why the Mind has a Body, 1903, 67-160. G. S. Fullerton, Is Matt an Automaton? in Popular Science § 5. For the character of mind as process, see W. Wundt, Philosophische § 6. On observation and experiment, see W. S. Jevons, The Principles of Science, 1900, Bk. iv., chs. xviii., xix. On introspection, see G. Spiller, The Mind of Man, 1902, 15-20, 34-37; W. B. Pillsbury, A Suggestion toward a Reinterpreta- tion of Introspection, in Journal of Philosophy, Psychology and Scientific Methods, i., 1904, 225-228. § 7. W. Wundt, Outlines of Psychology, 1907, §§ 19-21.
R. M. Yerkes, Animal Psychology and Criteria of the Psychic, in Journal of Philosophy, Psychology and Scientific Methods, ii., G. T. W. Patrick, The Psychology of Football, in American Journal of Psychology, xiv., 1903, 368-381.
1 The works cited under this heading throughout the book are of various degrees of difficulty, and their point of view is in many cases opposed to that of the author. To avoid confusion of thought, the student is advised to refer to them only after he has read the book through, and has thus formed a clear idea of the psychological system which it outlines. Difficulties and contradictions will then seem less formidable and less vital than they would if encountered at the beginning of his study of mind.
The dates given are those of current editions. Works that have passed through a number of editions are, however, quoted by chapter and section rather than by page, so that earlier editions may be used.
Note on the Classification of Psychology 43 T. Heller, Studien zur Blinden-Psychologie, in Philosophische Studien, xi., 1895, 226-253; 406-470; 531-562. § 8. C. L. Morgan, An Introduction to Comparative Psychology, 1894, W. Wundt, Volkerpsychologie, L, 1904, Einleitung; also Sprachgeschichte und Sprachpsychologie, 1901, § 1. M. F. Washburn, The Animal Mind, a Text-book of Comparative Psychology, 1908, chs. i., ii. § 9. O. Kuelpe, Introduction to Philosophy, 1897, Psychology, 55-67. W. James, Principles of Psychology, i., 1890, 1-4. H. Miinsterberg, Psychology and Life, 1899: essay on Psychology and Physiology, 35-99- NOTE ON THE CLASSIFICATION OF PSYCHOLOGY The following list of the various subdivisions of psychology is made on* on the basis of the distinctions drawn in § 7. We cannot hope to make the list final and complete. But it is well to realise, at the begin- ning of one's study of mind, how wide and varied is the territory that psychology covers.
I. Psychology of the Normal Mind A. Individual psychology i. Human psychology. This may be subdivided into: 1. General psychology, or the psychology of the adult civilised man. This is the principal topic of the text-books of psy- chology: see, for instance, W. James, Principles of Psychol- ogy, 1890; J. Sully, The Human Mind, 1892.
2. Special psychology, or the psychology of the human mind in some other stage than that of adult manhood. Special psy- chology thus includes infant psychology, child psychology, the psychology of adolescence, the psychology of senility, etc. These psychologies are often written from the genetic point of view. — W. Preyer, The Mind of the Child, 1868-9 [Die Seele des Kindes, 1900]; G. S. Hall, Adolescence, 1904.
3. Differential psychology, or the study of the differences between individual minds. The minds compared may belong to per- sons of the same race, class, age, sex, etc., or to persons who differ in these respects. — L. W. Stern, Weber Psychologic der \S 44 Subject-matter, Method and Problem of Psychology individuellen Differenzen, 1900; A. Binet, V Etude experi- ment ale de Vintelligence, 1903. 4. Genetic psychology, which seeks to trace the development of mind from infancy to manhood, and its gradual decay in old age. — J. M. Baldwin, Mental Development in the Child and the Race, 1906. ii. Animal psychology. This may be subdivided, like human psy- chology, into general, special, differential and genetic psy- chology. Since the workers in the field of animal psychology have, for the most part, been interested in the problems of mental evolution, animal psychology as a whole is often termed genetic psychology: but this is a misnomer. — E. Thorndike, Animal Intelligence, 1898; H. S. Jennings, Be- haviour of the Lower Organisms, 1906. iii. Comparative psychology. This is the comparative study, either of various types of animal mind, or of the minds of the animals and of man. It may be general, special or genetic. Like animal psychology, and for the same reason, it is often termed genetic psychology. — C. L. Morgan, An Introduc- tion to Comparative Psychology, 1894; W. Wundt, Lectures on Human and Animal Psychology, 1896 [Vorlesungen iiber die Menschen- und Thierseele, 1906]; M. F. Washburn, The Animal Mind, 1908.
B. Collective psychology The divisions of this department of psychology are not as yet sharply defined. We may, however, distinguish: i. Social psychology, which includes the study of the social conscious- ness, and also the study of the products of the collective mind: language, law and custom, myth and religion. — G. Tarde, Social Latvs, 1899; J. M. Baldwin, Social and Ethi- cal Interpretations in Mental Development, 1906; W. Wundt, Volker psychologic, 1 904-8. ii. Ethnic psychology, the differential psychology of nations or races. — G. le Bon, The Psychology of Peoples, 1898; W. H. R. Riv- ers and C. S. Myers, Cambridge Anthropological Expedition to Torres Straits, 190 1-3.
iii. Class psychology, the differential psychology of classes, professions, etc. — E. Tardieu, Psychologic militaire, 1898; L. Dauriac, Essai sur V esprit musical, 1904.
Note on the Classification of Psychology 45 II. Psychology of the Abnormal Mind A. Individual psychology i. Psychology of deficient and exceptional minds. — M. Howe and F. H. Hall, Laura Bridgman, 1903; C. Lombroso, The Man of Genius, 1891 [Z,1 uomo digenio, 1894].
ii. Psychology of mental derangement, the study of temporary abnor- malities of mind. — A. Maury, Le sommeil et les rtves, 1878; A. Moll, Hypnotism, 1890; E. Parish, Hallucinations and Illusions, 1897; S. de Sanctis, I sogni, 1899.
iii. Psychology of mental disorder, the study of the permanently de- ranged mind. — T. Ribot, Diseases of Personality, 1895; G. Stdrring, Mental Pathology in its Relation to Normal Psy- chology, 1907.
B. Collective psychology Psychology of mental derangement. — J. Jastrow, Fact and Fable in Psy- chology, 1900; S. Sighele, La foule criminelle, 1901.
SENSATION § io. The Elementary Mental Processes. — It is very im- portant that we make no mistake as regards the nature and number of the elementary mental processes. For these elements are the simple materials out of which we are to build up our entire psychology. They must, there- fore, be various enough and numerous enough to give rise, by their connections, to all the complicated phases of the human mind: to thought and sentiment, to memory and imagination, to emotion and perception. On the other hand, they must be strictly elementary; they must remain unchanged, however persistent our attempt at analysis and however refined our method of investigation. If the list is not complete, we shall be forced presently to smuggle in new elements: and that means bad logic and bad science. If we now pass as elementary any process that is really complex, we are guilty of a sheer blunder, and shall pay for it later on.
Here, however, is a dilemma. The science of psychol- ogy is still in the making; and, until it is rounded out and finished off, no final list of the mental elements can pos- sibly be drawn up. We must make a decision in the mat- ter; but we must not be dogmatic: we must stand ready to modify our decision, if the results of future research prove us to be wrong. Such a state of affairs is, perhaps, a little discouraging, since a right choice of elements is of cardinal importance; but it is not unnatural, nor is it dis- 46 § io. The Elementary Mental Processes 47 creditable to psychology. All scientific problems require time for their solution; and this problem of the nature and number of the mental elements is comparatively new, — certainly not older than the middle of the last century. So long as mind was looked upon as a substance, a real being, a personal creature, psychology had no more to do than to note down the different powers or faculties or capacities of the mind, as they fell under observation. The list always remained open. Not until mind is re- garded as a stream of processes, whose flow is through- out obedient to psychological law, does the problem of analysis become insistent. Besides, this problem can be solved only by help of the experimental method; and the first laboratory of psychology was founded as late as 1879. It is not surprising, then, that psychologists should still disagree as to the mental elements. Every year sees the proposal of some fresh process as candidate for element- ary rank; every year brings proof that one or other of the older candidates must, after careful scrutiny, be debarred from competition. And this back-and-forth movement will continue, we must suppose, for many years to come.
There is, nevertheless, beneath all these cross-currents of controversy, a fairly definite trend of psychological opinion in the matter of the elementary processes. The list that we adopt in this book is accepted by a large num- ber of psychologists, and, as a working hypothesis, has so far proved adequate to the composition of the human mind. If it has to be changed in the future, we may be tolerably sure that the change will come by way of addition, and not of subtraction, so that our acceptance of it will give us nothing to unlearn. — We set to work upon the assump- tion that there are at most three classes of mental ele- 48 Sensation ments; that two of these may, without any hesitation, be considered as sub-classes under a single general heading, even if they may not be grouped outright in a single class; and that all three may, with some show of probability, be viewed as processes of the same ultimate type.
The three classes of elementary processes are known as sensations, images, and affections. Sensations are, of course, the characteristic elements of perceptions, of the sights and sounds and similar experiences due to our pres- ent surroundings. Images are, in just the same way, the characteristic elements of ideas, of the mental pictures that memory furnishes of past and imagination of future expe- rience. Sensations and images are so much alike that they are not seldom confused; we shall discuss their relations in detail in § 61. Lastly, affections are the characteristic elements of emotions, of love and hate, joy and sorrow. At first sight, they appear to be essentially different from sensations and images, though a closer examination brings out a number of fundamental resemblances. We shall dis- cuss them in § 69.
It is our business, then, to describe and explain these elementary processes, and to show that, when grouped and arranged in certain uniform ways, they give rise to the different complex processes that constitute human consciousnesses.
We shall have occasion, later on, to say something about vari- ous other processes that have been put forward as elementary. Many psychologists, for instance, accept an additional class of relational elements. A quotation from Herbert Spencer will show what is meant. "The proximate components of mind," he writes, "are of two broadly-contrasted kinds — Feelings and the Rela- tions between feelings. [The word ' feelings ' here may be taken § ii. Elements and Attributes 49 to include our sensations, images and affections.] Under an ulti- mate analysis, what we call a relation proves to be itself a feeling — the momentary feeling accompanying the transition from one conspicuous feeling to an adjacent conspicuous feeling. Notwith- standing its extreme brevity, its qualitative character is apprecia- ble." Y These relational processes we discuss in § 140. Again, some psychologists have postulated a conative element, or ele- mentary process of will; others have set thoughts, as elementary processes, alongside of sensations and images. These, too, we discuss, in §§ 127, 139. The great majority of such pretenders may, however, be passed over in silence. They die and are dis- sected in the pages of psychological magazines, and do not live long enough to be mentioned in text- books.
§11. Elements and Attributes. — We have taken it for granted that the mental elements may be arranged in groups or classes. It may be objected that, since they are elements, — since they resist analysis, and cannot be re- duced to anything simpler than themselves, — we can have no means of grouping them. How is it possible to find degrees of likeness and degrees of difference between absolutely simple things?
The psychologist arranges the mental elements precisely as the chemist classifies his elementary substances. The chemical elements are divided, for instance, into metals and non-metals. The metals have a high power of reflect- ing light; they are opaque; they are good conductors of heat and electricity; they have high specific gravities. So they are set off, as a group, from the non-metals. These latter, again, include both gaseous and solid elements. That is to say, the chemical elements possess certain prop- 1 Principles of Psychology, 1881, vol. I., pt. ii., ch. ii., § 65. The quotation has been somewhat simplified.
5<D Sensation erties or attributes, by means of which they may be dis- tinguished and arranged.
It is just the same with the mental elements. These are simple, it is true, in the sense that they are mental experi- ence reduced to its lowest terms; but they are still real processes, still actual items of mental experience. Hence, like the chemical elements, they show various aspects or attributes, — present different sides, so to speak, — each of which may be examined separately by the psychologist. It is by reference to these attributes that introspection is able to classify them under different headings. — i There is no more agreement in psychology about the \ 1 attributes of the mental elements than there is about the p* ( elements themselves. It is, indeed, probably true to say > yVutnat there is not so much; the lists given in the different J- 'text-books seldom correspond in all details.
Various reasons may be given for this divergence of opinion. It is often said, for example, that the psycholo- gist must remain in doubt as regards the attributes of a mental element because he can never actually isolate the element itself, in order to bring it under separate observa- tion. The human mind is so complex, and the avenues of approach to the human nervous system are so numerous, that he can never reduce consciousness to a single, simple process. Now in strictness this statement is, no doubt, entirely correct. At the same time, it is possible to arrange experimental conditions in such a way that, for all practical purposes, one process and one process only is presented for observation. If we rule out distracting influences, and concentrate the attention upon, say, a particular sensation, then this sensation stands out clear and distinct, and all the rest of consciousness becomes a vague blur of indifferent T.
§ n. Elements and Attributes 51 processes. Practically, therefore, the psychologist can isolate a mental element, and canT as was said ahovf^py- amine separately its various aspects or attributes. The reason for difference of opinion in regard to these attributes must be sought elsewhere.
The chief reason lies in the difficulty of deciding what is original in tne sensation, inherent in it, constitutive of it, and wnat is mere accretion. The human nervous system, we must remember, has an immensely long history, is the outcome of long ages of development. The result is that it is full of short cuts; it is shot through and through with paths of direct connection. When, therefore, we think that we have a bare sensation before us, it is quite possible that we are, in reality, observing a complex process. What appears to be an aspect or attribute of the sensation may, in reality, be a separate process, so habitually and insepara- bly connected with the sensation in the past as now to seem an integral part of it. Let us take an instance.
We hear two tones, from the deep bass and the high treble. The former sounds voluminous and massive; the latter sounds small and sharp. Are we to conclude, then, that volume is an original attribute of tones? that tonal sensations possess a kind of solidity, a vague extension in the three dimensions of space? Some psychologists accept this conclusion. Others believe, on the contrary, that the volume which attaches to tones is a distinct process, and that it belongs not to hearing but to sight. When we hear a deep tone, that is, we are reminded of things that look large and soft; and when we hear a high tone, we are re- minded of things that look small and hard: there is nothing large or small, soft or hard, about the tones themselves. Here, then, is the difficulty, — in deciding what is inherent 5 2 Sensation in tonal sensation and what is merely accessory: there is no difficulty in isolating the tones for s^parate observa- tion.
Another reason may be found in the fact that, the more closely a particular kind of element is studied, the more many-sided is it likely to appear. Hence the specialist in any department of psychology will sometimes claim for his elements a larger number of attributes than the student of general psychology can discover in them. We may again illustrate this difference of opinion by reference to tones. Most of us would be disposed to think that a sensation of tone is characterised, simply and sufficiently, by its pitch, its definite position — high or low — upon the tonal scale. But the special student tells us that what we take to be a simple attribute of pitch is, in point of fact, the unanalysed resultant of no less than three distinct attributes.
Agreement will come with time; persistent observation, refining the longer it is continued, will someday settle the questions that we are here discussing. Meanwhile, the important thing is that we keep our minds open, and ob- serve as carefully and impartially as we can. And if there are many occasions when we must speak less positively than we could wish, there is, on the other hand, the com- forting reflection that an unfinished science is a good deal more interesting than a science whose facts and laws are already cut and dried.
§ 12. The Attributes of Sensation. — A sensation, as the term is used in this book, may be denned as an elementary mental process which is constituted of at least four attri- butes,— quality, intensity, clearness and duration. There are sensations for which the list of attributes is longer; but § 12. The Attributes of Sensation 53 these four are essential. We will consider them briefly, in the order of mention.
Quality is, so to say, an individual attribute; it is the attribute which distinguishes every elernentary process from every__other. It is, accordingly, the attribute which gives a sensation its special and distinctive name: cold, blue, salt, b^, — these are all names of sensation qualities. Intensity is the attribute to which we refer when we say that a given sensation is brighter or duller, louder or fainter, heavier or lighter, stronger or weaker, than another sensa- tion. In making such comparisons, we think of the sen- sations as possessing the same quality: both are blue, both are b^, both are pressure, both are cold or salt or asafoe- tida: but these two sensations, of the same quality, lie at two different points upon a finite scale of sensation degrees, which begins at a lower limiting value and rises to a max- imum. The more intensive sensation is placed higher up, the less intensive lower down, upon the scale of intensities. Clearness, again, is the attribute which gives a sensation its particular place in a consciousness: the clearer sensation is dominant, independent, outstanding, the less clear sensa- tion is subordinate, undistinguished in the background of consciousness. If, for instance, we are listening to tones