useless is what the people concerned perceive and judge to be of no use to themselves, then how are you going to keep psychology out of the reckoning? Must not your first duty be to get into touch, by means of sympathetic insight, with the whole mentality, the whole purposive scheme of life, of those whose customs you seek to differentiate as variously helpful and not helpful? When you apply your criterion of uselessness, are you not playing the psychologist all the while, though it may be without knowing it?
In the Western islands of Torres Straits, says Dr. Rivers by way of example, the mother's brother enjoys in certain respects more authority than does the father. Thus, if he commands his nephew to cease fighting, the latter must immediately obey; whereas, if his father gives the order, the young man is wont to exercise a certain discretion in the matter. Now this function of the mother's brother must be a survival, argues Dr. Rivers, because it cannot be useful, but is on the contrary likely to be harmful, that a child should be called upon to serve two masters. If those ties of affection and of a common habitation which unite father and son are in this way relaxed, the social order must correspondingly suffer. Now in so stating his case Dr. Rivers gives one the impression of having taken that most perilous of shortcuts, the "high priori road." He does not tell us that he found the boys of the Western islands of Torres Straits to be more disorderly than other boys of his acquaintance. He cannot cite the declaration of some peevish house-father to the effect that the peace-making efforts of his wife's brother brought about more harm than good. Instead, he simply makes appeal to our patriarchal prejudices. One may be sure, however, that so sound an empiricist as Dr. Rivers had duly taken note, while dwelling among these islanders, of a stream of conscious or subconscious tendency making in general for a strictly patriarchial system, but in this particular matter of the brother-in-law's power of interference
