2. Individual selection, which is natural selection working upon
individuals who are brought into competition with one another for
life and death. For instance, let us suppose that a man of genius
who has not yet given to the world his invention — his machine
which, if produced by him, would have great influence upon the
condition of the working classes — that this man meets a burglar
in his library and is shot dead. Here is a case of natural selection which determines the course of social evolution in a nation
or in the world by the elimination of an individual. Such a case
shows that the natural selection of individuals is a condition of
importance — when the individuals are important — in social
development. But it is not a force even in biology, as we have
just seen. It is a negative condition ; a statement — in sociology
as in biology — of evolution as it is, rather than as it would have
been if the conditions had been other. This again is of especial
importance in those stages of sociality in which the direct competition of individuals by physical strength or mental acuteness
is in full operation.
3. The intrusion of the "physiological cycle." — In an earlier place (Sec. 43) we saw that the "cycle of causation" which psychological and sociological facts, such as beliefs, desires, etc., represent, often intrudes upon the operation of the "physiological cycle" by the personal selection of individuals in marriage. The physical heredity of the individuals is due to the mixed strains of the parents, and is in part, therefore, determined by their mutual choice of each other. The converse is also true : the physiological intrudes upon the sociological, and thus becomes an "extra-social condition" in its determination. This is seen in all cases in which physical heredity works results in individuals or groups which incapacitate them, especially endow them, or modify in any way their social fitness. A tall, manly race of men would have social advantages in winning wives from a higher group, and such marriages would tell at once inside their
real causes; the survival or selection which "natural selection" formulates is an ex post facto statement of results. It merely states that no further force of a posiuve sort is necessary (as against, e. g., "special creation"). The distinction between "forces," which are intrinsic, and "conditions." which are not intrinsic, to the particular content, might well be traced through the sciences from biology to ethics.
