Postmodern philosophy is a philosophical movement that arose in the second half of the 20th century as a critical response to assumptions allegedly present in modernist philosophical ideas regarding culture, identity, history, or language that were developed during the 18th-century Age of Enlightenment. Postmodernist thinkers developed concepts like difference, repetition, trace, and hyperreality to subvert "grand narratives", univocity of being, and epistemic certainty. Postmodern philosophy questions the importance of power relationships, personalization, and discourse in the "construction" of truth and world views. Many postmodernists appear to deny that an objective reality exists, and appear to deny that there are objective moral values.
Jean-François Lyotard defined philosophical postmodernism in The Postmodern Condition, writing "Simplifying to the extreme, I define postmodern as incredulity towards meta narratives...." where what he means by metanarrative is something like a unified, complete, universal, and epistemically certain story about everything that is. Postmodernists reject metanarratives because they reject the conceptualization of truth that metanarratives presuppose. Postmodernist philosophers in general argue that truth is always contingent on historical and social context rather than being absolute and universal and that truth is always partial and "at issue" rather than being complete and certain.
Postmodern philosophy is often particularly skeptical about simple binary oppositions characteristic of structuralism, emphasizing the problem of the philosopher cleanly distinguishing knowledge from ignorance, social progress from reversion, dominance from submission, good from bad, and presence from absence. But, for the same reasons, postmodern philosophy should often be particularly skeptical about the complex spectral characteristics of things, emphasizing the problem of the philosopher again cleanly distinguishing concepts, for a concept must be understood in the context of its opposite, such as existence and nothingness, normality and abnormality, speech and writing, and the like.