Lyotard defines post-modern as incredulity towards metanarratives meaning that it denies the possibility of foundations for establishing the truth of statement existing outside of discourse
Foucault focuses on the power-knowledge relationship and sees the two as mutually constituted. It implies that there can be no truth outside of regimes of truth. How can history have a truth if truth has a history .
Foucault proposes a genealogical approach to look at history and this approach uncovers how certain regimes of truth have dominated others.
Derrida argues that the world is like text in that it cannot simply be grasped but has to be interpreted. He looks at how texts are constructed and proposes two main tools to enable us to see how arbitrary are the seemingly natural oppositions of language. These are deconstruction and double reading.
Post-modern approaches have been accused of being too theoretical and not concerned with the real word they however that in the social world there is no such thing as the real world in the sense of a reality that is not interpreted by us they have done a great deal of work on important empirical questions such as war and famonie