We have seen that there is a broad array of postmodern perspectives and positions, and that postmodern theories can be employed for quite different theoretical and political ends. Post-modern theories can be used to attack or defend modernity, to reconstruct radical politics or declare their impossibility, to enhance Marxian theory or to denounce it, to bolster feminist critiques or to undermine them. Almost all postmodern theories, however, explode the boundaries between the various established academic disciplines — such as philosophy, social theory, economics, literature — and produce a new kind of supradisciplinary discourse. Postmodern theorists criticize the ideals of representation, truth, rationality, system, foundation, certainty, and coherence typical of much modern theory, as well as the concepts of the subject, meaning, and causality. As Hassan puts it, post-modern theories are part of a culture of "unmaking" whose key principles include: "decreation, disintegration, deconstruction, decentrement, displacement, difference, discontinuity, disjunction, disappearance, decomposition, de-definition, demystification, detotalization, delegitimation" (1987: p. 92).