People who think of themselves as tough-minded and realistic, among them influential political leaders and businessmen as well as go-getters and hustlers of smaller caliber, tend to take it for granted that human nature is selfish and that life is a struggle in which only the fittest may survive. According to this philosophy, the basic law by which man must live, in spite of his surface veneer of civilization, is the law of the jungle. The "fittest" are those who can bring to the struggle superior force, superior cunning, and superior ruthlessness.