In the culture generally, postmodernism is associated with a playful acceptance of surfaces and superficial style, self-conscious quotation and parody (although these are also found in modernist literature, such as that of James Joyce), and a celebration of the ironic, the transient, and the glitzy. It is usually seen as a reaction against a naïve and earnest confidence in progress, and against confidence in objective or scientific truth. In philosophy, therefore, it implies a mistrust of the grands récits of modernity: the large-scale justifications of western society and confidence in its progress visible in Kant, Hegel, or Marx, or arising from utopian visions of perfection achieved through evolution, social improvement, education, or the deployment of science. In its post-structuralist aspects it includes a denial of any fixed meaning, or any correspondence between language and the world, or any fixed reality or truth or fact to be the object of enquiry.

The tendency was anticipated, and perhaps most brilliantly expressed, by Nietzsche, whose perspectivism is seen as a philosophical technique for dissolving the presumption that there can be objective knowledge. Objectivity is revealed as a disguise for power or authority in the academy, and often as the last fortress of white male privilege. Logical or rational thought is revealed as the imposition of suspect dichotomies on the flux of events. Postmodernists differ over the consequences of such discoveries, sharing the sceptic's old problem of how to think and act in the light of the doctrine. While the dismantling of objectivity seems to some to be the way towards a liberating political radicalism, to others it allows such unliberating views as the denial that there was (objectively) such an event as the Second World War or the Holocaust, and to others such as Rorty (Contingency, Irony and Solidarity, 1989), it licenses the retreat to an aesthetic, ironic, detached, and playful attitude to one's own beliefs and to the march of events. This retreat has been criticized as socially irresponsible (and in its upshot, highly conservative). The postmodernist frame of mind, charted, for example, in The Postmodern Condition, 1984, by Jean-François Lyotard, may seem to depend on a cavalier dismissal of the success of science in generating human improvement, an exaggeration of the admitted fallibility of any attempt to gain knowledge in the humane disciplines, and an ignoring of the quite ordinary truth that while human history and law admit of no one final description, they certainly admit of more or less accurate ones, just as a landscape permits of no one unique map, yet there can be more or less accurate maps.

(Source: Philosophy Dictionary)