he wholly disregards the progressive decrease in the
importance of the struggling function under the action of the other
parallel law of solidarity in the struggle.

Here comes in that constant principle in sociology, that the social
forms and forces co-exist always, but that their relative importance
changes from epoch to epoch and from place to place.

Just as in the individual egoism and altruism co-exist and will co-exist
always--for egoism is the basis of personal existence--but with a
continuous and progressive restriction and transformation of egoism,
corresponding to the expansion of altruism, in passing from the fierce
egoism of savage humanity to the less brutal egoism of the present
epoch, and finally to the more fraternal egoism of the coming society;
in the same way in the social organism, for example, the military type
and the industrial type always co-exist, but with a progressively
increasing predominance of the latter over the former.

The same truth applies to the different forms of the family, and also to
many other institutions, of which Spencerian sociology had given only
the _descriptive_ evolution and of which the Marxian theory of economic
determinism has given the _genetic_ evolution, by explaining that the
religious and juridical customs and institutions, the social types, the
forms of the family, etc., are only the reflex of the economic
structure which differs in varying localities (on islands or continents,
according to the abundance or scarcity of food) and also varies from
epoch to epoch. And--to complete the Marxian theory--this economic
structure is, in the case of each social group, the resultant of its
race energies developing themselves in such or such a physical
environment, at I have said elsewhere.

The same rule holds in the case of the two co-existing laws of the
_struggle for existence_ and of _solidarity in the struggle_, the first
of which predominates where the economic conditions are more difficult;
while the second predominates with the growth of the economic security
of the majority. But while this security will become complete under the
regime of socialism, which will assure to every man who works the
material means of life, this will not exclude the intellectual forms of
the struggle for existence which M. Tchisch recently said should be
interpreted not only in the sense of a _struggle for life_, but also in
the sense of a _struggle for the enrichment of life_.[95]