In seeking light on this subject we must understand what sort of problems arise from the contemplation of cultural facts and attempt to connect them with the established principles of psychology. A few concrete examples will illustrate the situation.

One of the striking characteristics of our civilization, a trait of our material culture that is nevertheless an invaluable, nay indispensable, means for the propagation of knowledge under modern conditions, is the existence of paper, that is, of a cheap, readily manufactured material for writing and printing. The obvious problem that develops from this fact is, How did we get the art of paper-manufacture? Now we shall search in vain our psychological literature in quest of an explanation. Höffding and James, Wundt and Titchener have no answer to offer. An answer, nevertheless, exists. Europe learnt the art of paper-making from the Arabs, who as early as 795 A. D. had established a paper factory in Bagdad. These in turn got their knowledge from the Chinese, who must be regarded as the originators of the technique. The answer is a perfectly satisfactory one, but it is obviously not couched in psychological terms: its nature is purely historical.

Nevertheless, an objection may plausibly be raised here. Though an explanation has certainly been given, it does not account for all aspects of the phenomena we are considering. There is a psychological basis for each and every one of the events in our historical series. This series we may subdivide into three stages—the invention by the Chinese, the borrowing of this invention by the Arabs, and its transmission from Arab to European. Now the two last-named processes of transmission may not suggest the necessity of a special explanation at all. One may think that all that was required was for the Europeans to watch the Arabs and for the Arabs to watch the Chinese, and presto! the thing was done. This indeed, seems to be the view of an influential school of modern ethnologists. But the case is far from being so simple. We know of many instances, in the higher no less than in the lower cultures, corresponding to what the biologist calls symbiosis—a condition where distinct communities or countries persist in a division of labor for mutual benefit, each trading some of its intellectual or material products for equivalents secured from the other. In many parts of Africa there are fixed markets in which negroes from fairly remote localities congregate for the barter of wares, which are thus diffused far from their source of origin; but it is the finished products, not the arts, that are diffused. In New Guinea trading-vessels carry such objects as pottery hundreds of miles from the area of manufacture to natives who remain as ignorant of the ceramic technique as before. In northern Arizona the Hopi Indians occupying three eminences not more than eight miles distant from one another have no perfect uniformity of industrial knowledge. Pottery, which flourishes on the eastern Mesa, is wholly unknown as an art, though constantly used in its specimens, by the people of the central Mesa; a certain type of basketry plaque is made only at Oraibi village; another type is manufactured exclusively on the central Mesa. Conditions more ideal a priori for a transfer of knowledge than among the practically homogeneous neighboring Hopi groups could not be conceived. Nevertheless, it has not taken place. Cultural diffusion, therefore, cannot be taken for granted. We cannot take one people, place it alongside of another, and effect a cultural osmosis in the same way in which we produce a chemical reaction when two substances are brought together under proper conditions of temperature. We are face to face with a selective, with a psychological condition. But when we turn once more to our text-books of psychology, we again find nothing that fits the case. About choice in general we get ample information. But we may rummage all the psychological seminar rooms in the world and yet shall find no reason why the Arabs learned the technique of paper-making from the Chinese instead of ignoring it or only importing Chinese paper.

Nor are we more fortunate when we turn to psychology for an account of how the original Chinese inventor came to conceive his epoch-making idea. This fact, of course, falls under the heading of ‘imagination’, and about imagination psychologists have much to tell us. But what, after all, does their interpretation amount to? We learn that imagination, as distinguished from the power of abstract thought, is the power of forming new concrete ideas. Since even the concrete individual idea is complex, being a product of association, its elements may be linked differently so as to produce new combinations. “The inventor of a new mechanism,” says Höffding, “combines given elements, the laws of whose activity he knows, into a totality and a connection which has no complete parallel in experience.” The scientist tries all possible combinations among his elements of experiences, forming a succession of individual ideas, which are rejected until the one appears that adequately represents reality.

We need hardly go farther to realize the impotence of psychological science for illuminating the psychology as well as the history of the paper-making art. The formulation of psychological science is admirable, but it is too general. It explains the invention of the steam-engine and the phonograph, the sewing-machine and the harvester no less than the origin of paper-making. We, however, do not want to know merely what ultimate psychological processes the invention of paper-making shares with all other inventions whatsoever, but also the differential conditions that produced this one and unique result under the given circumstances. It is as though we asked about a man’s character and were told that he was a vertebrate. The type of psychological explanation we want is by no means unknown; however, we shall find its illustrations not in text-books of psychology, but in histories of literature, science, and art. When Taine raises the question how such a bore as Dr. Samuel Johnson could conceivably have attained his position in English literature and answers that it is because of the English predilection for sermons, he is giving the type of solution—whether right or wrong—that we want to secure for our cultural problem; it explains why the average Englishman, as a member of English society, acquires the habit of regarding Johnson in a certain way. When we inquire why Newton closes his treatise on optics with a statement as to the vanity of human things, our curiosity is satisfied when this expression appears as only one instance of the blending of theological and scientific thought current in his day. It is nonsense to say that these explanations are purely historical; they are psychological, for they take fully into account the subjective attitudes involved in the phenomena studied; and it is hopeless to expect this sort of explanation from psychological science, which deals with a quite distinct and far more generalized form of mental activity.

To turn from the technique of paper manufacture to a very different cultural feature in order to test the possibility of merging the observed phenomena in the principles of psychology. In several parts of the globe, and most prominently in parts of South America, the aborigines practise a custom known as the ‘couvade’, which forces the father of a new-born child to subject himself to a period of inactive confinement and a series of rigorously observed dietary and other regulations. Let us, for the sake of bringing out the point in high relief, ignore all historical considerations and concentrate exclusively on the subjective elements involved. Whence, then, this strange and wholly irrational association of ideas between fatherhood and a group of taboos? Now the subject of the association of ideas occupies hundreds of pages in psychological literature, yet all this, in itself valuable enough, material has no bearing on our problem, because it is again far too general. We do not doubt for a moment that the association we desire to have illuminated is due either to contiguity or to a perceived similarity of ideas, but why have we this particular association instead of the limitless multitude of associations that would be equally intelligible by the same formulae?

Again, many aboriginal tribes of Australia are subdivided into two halves, membership in which is inherited through the father, in some cases, through the mother in others. These moieties are what is technically called ‘exogamous’, i.e., marriage with a fellow-member is strictly forbidden. The regulation is, indeed, so stringent, the feeling of horror evoked by a transgression so violent, that in former times offenders were promptly put to death. This sentiment is so strong that even when visiting a remote tribe, perhaps a hundred miles away, where there is no possibility of blood-kinship, an Australian will avoid marriage with a member of the moiety bearing the same name as his own. Here, surely, there is matter for psychology. An Australian has a violent emotional reaction akin to our aversion to incest, and may translate his feelings into the most violent action. Or, looking at the matter from another angle, the Australian exercises an admirable self-control, eschewing on principle marital relations with half the women of his community. Yet all that psychologists tell us of the ethical feelings and the will leaves the problem before us wholly untouched. Why this particular curious feeling developed, what place it occupies in mental life, the psychologist fails to explain. We get, again, simply general formulæ about feeling and will that are equally applicable to the case of a man’s beating his wife or a boy’s resisting the temptations of a lollypop. And this, it must be noted, is dealing with the distinctively psychological aspect of the data. Whether the rule in question originated in a common center and thence spread to other tribes, is also a cultural question of great importance, and this historical phase of the subject psychology is avowedly incompetent to deal with. Psychology, then, fails throughout to supply us with the interpretation we want. It is as impotent to reduce to really interpretative psychological principles the subjective aspect of cultural phenomena as it is to explain the historical sequence of events.

It is not necessary to multiply examples to establish the point. It is clear that cultural phenomena contain elements that cannot be reduced to psychological principles. The reason for the insufficiency is already embodied in Tylor’s definition of culture as embracing ‘capabilities and habits acquired by man as a member of society’. The science of psychology, even in its most modern ramifications of abnormal psychology and the study of individual variations, does not grapple with acquired mental traits nor with the influence of society on individual thought, feeling and will. It deals on principle exclusively with innate traits of the individual. Now, whether the sharp separation assumed here between the innate and the acquired, between individual activity as determined by uniquely individual potentialities and as determined by social environment, can be made in practice or not, one thing is clear: there are phenomena that are acquired and in no sense innate, that are socially and not individually determined. When a Christian reacts in a definite way to the perception of a cross, it is clearly not because of an individual psychic peculiarity, for other Christians react in the same way. On the other hand, we are not dealing with a general human trait since the reactions of a Mohammedan or a Buddhist will be quite different. Innumerable instances of this sort show that individual thought, feeling and volition are co-determined by social influences. In so far forth as the potency of these social factors extends we have culture; in so far forth as knowledge, emotion, and will are neither the result of natural endowment shared with other members of the species nor rest on an individual organic basis, we have a thing sui generis that demands for its investigation a distinct science.

Does it follow from the foregoing that there is no possible relation between psychology and culture, that psychological results are a matter of utter indifference to the ethnologist? In their desire to vindicate for their own branch of knowledge a place in the sun, some ethnologists have come very near, if they have not actually reached such a conclusion. To me the case appears in a somewhat different light. Whatever division of labor may be desirable for the economy of scientific work, knowledge as a whole knows nothing of watertight compartments. Further, the nominally distinct sciences are not subordinated to one another, but coexist in a condition of democratic equality and coöperativeness. We cannot reduce cultural to psychological phenomena any more than we can reduce biology to mechanics or chemistry, because in either case the very facts we desire to have explained are ignored in the more generalized formulation. But for specific purposes, the student of culture can call for aid upon each and all of the other branches of learning. It is a very important cultural problem whether the natives of South America knew the bronze technique, i.e., whether they consciously produced the observed alloy of copper and tin. But how can the ethnologist solve this problem? Only by requisitioning the services of the chemist.

Now very few would deny that services of the kind rendered by chemistry can also be rendered to the study of culture by psychology. Indeed, most people would at once admit that the relationship with psychology is a priori likely to be far more extensive and thorough-going. A few concrete examples will illustrate how this relationship may be conceived.