"Nietzsche … tried to apply to his own thought the teachings of cultural relativism. This practically nobody else does. For example, Freud says that men are motivated by desire for sex and power, but be did not apply those motives to explain his own science or his own scientific activity. But if he can be a true scientist, i.e., motivated by love of the truth, so can other men, and his description of their motives is thus mortally flawed. Or if he is motivated by sex or power, he is not a scientist, and his science is only one means among many possible to attain those ends. This contradiction runs throughout the natural and social sciences. They give an account of things that cannot possibly explain the conduct of their practitioners. The highly ethical economist who speaks only about gain, the public-spirited political scientist who sees only group interest are symptomatic of the difficulty of providing a self-explanation for science and a ground for the theoretical life, which has dogged the life of the mind since early modernity but has become particularly acute with cultural relativism."