Trotter maintains that the tendency of nature is to increase and maintain the homogeneity of the species, but we should say rather that the whole process of differentiation and organization is upon a level in which the biological processes that make for or against homogeneity have but little effect. The task before man is social. It is not so much a consciousness of his destiny as a species that man requires, but of his work as an organized group. It is due to a rapid differentiation and increase in man's desires that he has become a species in which there is internal warfare. It must be by the control of these desires in a conscious process of organization that he will become, if ever, a well-ordered and homogeneous group. Trotter thinks of such a change as a biological phenomenon, as being one of those momentous steps which a very few times have been taken in the development of organic life in the world. We cannot discuss fully here these biological views, as they relate to the future organization of the world. That the explanation of wars within the human species this view affords is correct so far as it goes one would admit. Men fight among themselves as animals do not, because of their differences. We should prefer to think of these differences, however, neither as a phase of biological differentiation as structural change nor as functional adaptation by differentiation of reactions to the same stimuli, but as the effect of the new consciousness of desires that came with the rise of man from the animal stage, and the conditions under which these desires could and must be realized. It is the complexity of interests that has given to man his antagonisms and his differences, and these secondary differences have been utilized as a means of still further developing the desires and satisfying them, or justifying their satisfaction. It is man's intelligence and his capacity for being governed in his conduct by many desires that teaches him to make war upon his own kind, and the very same qualities make his associations firm and lasting. _But just in this way the human group ceases to be a herd and to be dominated by herd instincts._ To interpret war, therefore, as an effect of social instinct or herd instinct upon the instincts of aggression or of self-protection, or as the effect of aroused instincts of aggression and self-protection exciting the herd instinct, is unsatisfactory because it is too simple, and erroneously undertakes to explain human life in terms of instinct and also carries biological analogies too far. These views, if we understand them, seem to have the characteristic faults of all purely biological sociology.