The Relations of Sociology to Other Sciences. [Footnote: For a fuller discussion of the relations of sociology to other sciences and to philosophy see my article on "Sociology: Its Problems and Its Relations" in the _American Journal of Sociology_ for November, 1907.]--(A) _Relations to Biology and Psychology._ In attempting to give a scientific view of social organization and social evolution, sociology has to depend upon the other natural sciences, particularly upon biology and psychology. It is manifest that sociology must depend upon biology, since biology is the general science of life, and human society is but part of the world of life in general. It is manifest also that sociology must depend upon psychology to explain the interactions between individuals because these interactions are for the most part interactions between their minds. Thus on the one hand all social phenomena are vital phenomena and on the other hand nearly all social phenomena are mental phenomena. Every social problem has, in other words, its psychological and its biological sides, and sociology is distinguished from biology and psychology only as a matter of convenience. The scientific division of labor necessitates that certain scientific workers concern themselves with certain problems. Now, the problems with which the biologist and the psychologist deal are not the problems of the organization and evolution of society. Hence, while the sociologist borrows his principles of interpretation from biology and psychology, he has his own distinctive problems, and it is this fact which makes sociology a distinct science. Sociology is not so easily distinguished from the special social sciences like politics, economics, and others, as it is from the other general sciences. These sciences occupy the same field as sociology, that is, they have to do with social phenomena. But in general, as has already been pointed out, they are concerned chiefly with certain very special aspects or phases of the social life and not with its most general problems. If sociology, then, is dependent upon the other general sciences, particularly upon biology and psychology, it is obvious that its relation to the special sciences is the reverse, namely, these sciences are dependent upon sociology. This is only saying practically the same thing as was said above when we pointed out that industry, government, and religion are but expressions of human social life. In other words, sociology deals with the more general biological and psychological aspects of human association, while the special sciences of economics, politics, and the like, generally deal with certain products or highly specialized phases of society.