sociology which deals with such problems _Social Statics_. But the
problems which are of most interest and importance in sociology are
those of social evolution. Under this head we have the problem of the
origin of society in general and also of various forms of association.
More important still are the problems of social progress and social
retrogression; that is, the causes of the advancement of society to
higher and more complex types of social organization and the causes of
social decline. The former problem, social progress, is in a peculiar
sense the central problem of sociology. The effort of theoretical
sociology is to develop a scientific theory of social progress. The
study of social evolution, then, that is, social changes of all sorts,
as we have emphasized above, is the vital part of sociology; and it is
manifest that only a general science of society like sociology is
competent to deal with such a problem. Inasmuch as the problems of
social evolution are problems of change, development, or movement in
society, Comte proposed that this division of sociology be called
_Social Dynamics_.

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