THERE are many factors which influence international relations. Among the most important are language, culture, religion and commerce. If the peoples of two countries speak the same language intercourse between them is much easier and sympathetic relations are likely to exist between them. If two nations are of about the same culture with respect to the development of science and art, the diffusion of knowledge, moral standards, etc., this culture is likely to serve as a bond of union. But if the cultural differences are great they may give rise to a feeling of antipathy, or, to say the least, the one nation is almost certain to look down upon the other nation as being of a lower grade of culture. If two nations are of the same religion this may serve as a bond of union. But if they are of different religions this difference may give rise to hostility, especially if one or both of these religions are of a militant sort. If two nations have commercial relations which are to the mutual benefit of both they are almost certain to remain on friendly terms with each other. But if they are rivals in commerce such rivalry is very likely to lead to hostility and sometimes to war.
In this article we are to discuss the part played by ethnic factors in international relations. That is to say, we shall try to ascertain to what extent and how ethnic differences between the peoples of nations affect the relations of those nations towards each other. These differences are with respect to external anatomical characteristics such as stature, facial features, the color of the skin, the character of the hair, etc., and with respect to the internal organs, such as the brain, and the nervous system in general, the heart, lungs, etc., all of which play a part in determining the psychic characteristics of a people. It is, however, very difficult to segregate these factors and to study their effects because they are inextricably mingled with the other factors which have been mentioned. This is true, in the first place, because these ethnic characteristics have their influence in part indirectly through the other factors. That is to say, the language, culture, religion, etc., of a people are determined in varying degrees by these ethnic characteristics. But it is very difficult to determine in any specific case to what extent this is true as compared to the influence of physical environment and such chance circumstances as relations to other peoples.
It is also difficult to determine how ethnic differences influence international relations directly. These differences frequently give rise