Post-Modernism is a broad movement in late 20th Century philosophy and the arts, marked in general terms by an openness to meaning and authority from unexpected places, and a willingness to borrow unashamedly from previous movements or traditions. It is often defined negatively as a reaction or opposition to the equally ill-defined Modernism, although some claim that it represents a whole new paradigm in intellectual thought.
The term "Post-Modernism" (literally "after Modernism") originated in architecture to denote a reactionary movement against the perceived blandness and hostility of the Modernist movement, and also against the pretensions of high Modernism, with its pursuit of an ideal perfection, harmony of form and function, and dismissal of frivolous ornamentation. It came to be used in art, music and literature (and, by analogy, in philosophy) for any pluralistic or reactionary style that is often more ornamental than Modernism, and which is not afraid to borrow from previous artistic styles, often in a playful or ironic fashion. It tends to lack a clear central hierarchy or organizing principle, although it often embodies extreme complexity, contradiction, ambiguity, diversity and inter-connectedness or inter-referentiality, and is typically marked by a revival of traditional elements and techniques.
Some see Post-Modernism as just another phase in the continued unfolding of Modernism; some see it as a complete replacement for, and backlash against, Modernism. The burgeoning anti-establishment movements of the 1960s can be considered as the constituting event of Post-Modernism in a more general sense. With the current wide availability of the Internet, mobile phones, interactive television, etc, and the instantaneous, direct, shallow and often superficial participation in culture they allow, some commentators have even posited that we are now entering the Post-Post-Modern period.
In Philosophy specifically, Post-Modernism was heavily influenced by Continental Philosophy movements like Phenomenology, Structuralism and Existentialism, and it is generally skeptical of many of the values and bases of Analytic Philosophy. It is generally viewed as an openness to meaning and authority from unexpected places, so that the ultimate source of authority is the actual "play" of the discourse itself. It can be considered a "pick-and-mix" approach, whereby basic problems are approachable from a wide range of theoretical perspectives.
Post-Modernism is a broad and non-specific movement (if it can be described as a movement at all), and movements like Deconstructionism and Post-Structuralism (among others) can both be considered Post-Modernist. Post-Modernists often defend themselves from criticisms of philosophical incompetence and excessive informality by claiming that they take a "wider" view of what philosophy is, that their use of academic jargon is necessary to communicate their ideas, and that their critics simply do not understand their work.
Among the best-known Post-Modernist philosophers are Michel Foucault, Jacques Derrida, Jean-François Lyotard (1924 - 1998), Richard Rorty (1931 - 2007), Jean Baudrillard (1929 - 2007) and Roland Barthes (1915 - 1980). Lyotard is perhaps one of the most identifiable Post-Modernists, and he has described Post-Modernism as a condition of the present state of culture, social structure and self. He is largely concerned with the role of narrative in human culture, and particularly how that role has changed as we have left modernity and entered a post-industrial or post-modern condition. Baudrillard has argued that we live in a "hyperreal", post-modern, post-industrial, post-everything sort of a world, and global reality has become dominated by an internationalized popular culture to such an extent that people have great difficulty deciding what is real.