We are now in the process of wakening from the nightmare of modernity, with its manipulative reason and fetish of the totality, into the laid-back ["joyful," as Nietzsche would say] pluralism of the postmodern, that heterogeneous range of life-styles and language games which has renounced the nostalgic urge to totalize and legitimate itself....Science and philosophy must jettison their grandiose metaphysical claims and view themselves more modestly as just another set of narratives.
In other words, what as a result of Nietzsche's Fröliche Wissenschaft has been called into question in these postmodern times is that which has served always as the ultimate legitimation of the philosophical enterprise: the search for Truth, for Knowledge, for, that is to say, Science (Wissenschaft, episteme). i.e., the One (Universal), True Account of Things (Reality) (true heirs to Parmenides and Pythagoras, present-day physicists are currently expending a great deal of money and energy in search of what they call the Theory of Everything, "a single equation that describes the entire universe"). What under the inspiration of Nietzsche postmodernism has called into question is the foundational, cultural authority of Science.
The concept of Science is a Platonic invention, but it underwent a new twist at the beginning of modern times with the emergence of mathematical, experimental science of the Galilean sort. Modern philosophy can be said to have begun when, bedazzled by this new development, philosophers took the new science as the supreme model of genuine, foundational knowledge. They were, ever afterwards, to labor in the shadow cast by this great Idol. Even the "free thinking," godless philosophers of late modernity continued to pay a sort of religious hommage to it. As Nietzsche remarked in the Genealogy of Morals, "They are far from being free spirits: for they still have faith in truth." And as he went on to say: "It is still a metaphysical faith that underlies our faith in science--and we men of knowledge of today, we godless men and anti-metaphysicians, we, too, still derive our flame from the fire ignited by a faith millennia old, the Christian faith, which was also Plato's, that God is truth, that truth is divine." When at long last Nietzsche took to doing philosophy with a hammer, it was precisely this Idol that he sought to demolish.