within the group.

Biologically distinct groups may thus be unified biologically only by
intermarriage, while socially physically distinct groups may be
unified socially and psychically without intermarriage, but
exclusively through association.

The psychic defects of the offspring of interracial marriages may be
largely due to the defective social heredity transmitted by the
parents, rather than to mixed intrinsic inheritance.

The term "race soul" is a convenient, though delusive, because highly
figurative, expression for the psychic unity of a social group. The
unity is due entirely to the more or less complete possession by the
individual members of the group, of common ideas, ideals, methods of
thought, emotions, volitions, customs, institutions, arts, and
beliefs.

Each individual is molded psychically to the type of the social group
in which he is reared. The "race soul" is thus imposed on the
individual by conscious and unconscious education.

The psychic evolution of social groups is divergent so long as
isolation is fairly complete, but becomes convergent in proportion to
association. Perfect association produces complete psychic unity,
though it should be noted that perfect association of geographically
separated social groups is practically unattainable.

The essential elements constituting national unity are psychic and
social, not biological. Racial unity is biological. The same race may
accordingly separate into different social and psychic groups. And
members of different races may belong to the same social psychic
group.

The so-called "race soul" of many sociologists is, therefore, a
fiction and indicates mental confusion. The term refers not to the
racial unity of inherent psychic nature, but only to the social unity
of socially inherited psychic characteristics. Groups thus socially
unified may or may not be racially homogeneous. In point of fact no
race is strictly homogeneous biologically, nor is any social group
completely unified psychically.

In sociology as in biology function produces organism, that is to say,
activity produces the organ or faculty fitted to perform the
activity.[2] The psychic characteristics differentiating social groups
are chiefly, and perhaps exclusively, due to diverse social
activities. These activities are determined by innumerable causes,
geographical, climatic, economic, political, intellectual, emotional,
and personal.

The plasticity of a psychic grou