This century has been characterized by a strong and pervasive belief in "certainty through science. " It is a belief that has been nurtured by philosophers, scientists, and governing bodies alike. And, where vocal reassurance has failed to convince, modem technology has more than compensated. It has, in effect, been a century in at last to be making significant headway toward objective which humankind seemed and enduring truth. Yet, as the century winds toward its conclusion, this optimistic belief has begun to confront a challenging array of attacks. Widespread signals of concern are increasingly evident, and in the philosophy of science little but remnants remain of the bold rationale that once promised truth through method. One now senses a profound alteration taking place in both the concept of knowledge and of science-an alteration that may prove to be as significant as the Copernican revolution, the emergence of Darwinism, or the development of Freudian theory. As a result of the latter transformations, humans are no longer seen as the center of the universe, as essentially different from animals, or as fully conscious of the wellsprings of their activity. In the present case, however, we confront the loss of the human capacity for objective knowledge.