A scientific color is often given to the philosophy of force, as expressed by the authors just referred to, by an appeal to evolutionary and biological laws. It is urged that the condition of man's advance in the past has been the survival of the fit by struggle and warfare, and that in that struggle it is precisely those endowed with combativeness and readiness to fight who have survived. Thus the tendency to combat is not a mere human perversity, but is part of the self-protective instinct rooted in a profound biological law--the struggle of nations for survival. This point of view is expressed by S.R. Steinmetz in his "Philosophie des Krieges." War, according to this author, is an ordeal instituted by God, who weighs the nations in its balance. It is the essential function of the State, and the only function in which peoples can employ all their powers at once and convergently. No victory is possible save as the resultant of a totality of virtues; no defeat for which some vice or weakness is not responsible. Fidelity, cohesiveness, tenacity, heroism, conscience, education, inventiveness, economy, wealth, physical health and vigor--there is no moral or intellectual point of superiority that does not tell when "God holds His assizes, and hurls the peoples one upon another" (Die Weltgeschichte ist das Weltgericht); and Dr. Steinmetz does not believe that in the long-run chance and luck play any part in apportioning the issues. It is urged that international hostility is merely the psychological stimulus to that combativeness which is a necessary element of existence, and that though, like other elemental instincts--our animal appetites, for instance--it may in some of its manifestations be ugly enough, it makes for survival, and is to that extent a part of the great plan. Too great a readiness to accept the "friendly assurances" of another nation and an undue absence of distrust would, in accordance with a sort of Gresham's Law in international relationships, make steadily for the disappearance of the humane and friendly communities in favor of the truculent and brutal. If friendliness and good-feeling towards other nations led us to relax our self-defensive efforts, the quarrelsome communities would see, in this slackening, an opportunity to commit aggression, and there would be a tendency, therefore, for the least civilized to wipe out the most. Animosity and hostility between nations is a corrective of this sentimental slackness, and to that extent it plays a useful rôle, however ugly it may appear--"not pretty, but useful, like the dustman." Though the material and economic motives which prompt conflict may no longer obtain, other than economic motives will be found for collision, so profound is the psychological stimulus thereto.