Jean-François Lyotard was a French philosopher whose hugely influential book The Postmodern Condition was partly responsible for sparking off the wide-ranging debate about postmodernism in the social sciences and humanities. After early involvement in French leftist circles, Lyotard became increasingly suspicious of Marxism, arguing that libidinal energies provided the basis of any valid understanding of political economy. Spending most of his career as a professor at University of Paris VIII, as well as working in the USA, most notably as Professor of Critical Theory at the University of California, Irvine, he developed this perspective into the outlook outlined in his other well-known book, Libidinal Economy. His later work continued to expound the significance of his analysis of the postmodern condition and his account of libidinal energies, applying them to subjects such as aesthetics and the media. Polity has published his books The Inhuman and Why Philosophize?