PRESENT PROBLEMS OF SOCIAL PSYCHOLOGY 463
move along the line of control, more and more subjecting private opinion and conduct to general opinion, and secreting morality and law as binding material. If my surmise be correct, we are called upon to trace these diverging lines of group-development, and to discriminate the forces at work in each of these evolutions.
Lest I be reproached for bounding the field of collective psy- chology, rather than pointing out the particular problems it ought to attack, let me state some of the concrete questions that are puzzling me today.
Which architect is the chief builder of group-units, Resem- blance between the units or Community of Interest ? Does aware- ness of resemblance inspire sympathies, which dispose men to unite their efforts in the joint assertion of common interests, which were there all the time, but for which they would not con- sent to co-operate? Or, does some grave posture of affairs, which establishes among men a community of interest, compel them to co-operate; and does their gratitude to one another for these services of mutual aid inspire sympathies which perpetuate the union after the occasion for it has passed away? In the one case men cleave to their kind and shun opposites; in the other case they seek helpers and shun competitors. The one emphasizes ideas, the other material interests, as source of the sentiments which unite or divide men. It may be that the latter hypothesis holds for political association, while the former holds for cultural association. Moreover, it may be that one type prevails in the impulsive stage of human development, while the other type tends to prevail in the rational stage.
Granting that awareness of resemblances and differences determines the attitudes of persons toward one another, what is the relative importance of the various traits in which people may agree or differ? As regards physique, the thorough mix-up of cephalic races suggests that head-form is insignificant. Color, on the other hand, is an outstanding trait, and color-contrast is almost always a hindrance to social feeling and a bar to inter- marriage. In ancient India, as in our South, color seems to have been the foundation of caste. The shock which a human being experiences on beholding a face of an unfamiliar hue is
