The Situationist International was a group of revolutionaries that was founded in 1957. Inspired by Marxist and avant-garde ideas, SI advocated lifestyles which rejected capitalism. They believed that the fulfillment of human desire would be achieved by the 'construction of situations' rather than the common passive spectatorship. SI resisted the formalization of their ideas into an ideology, but argued for the priority of real live, which means constant experimentation and evolution.
SI synthesized several smaller avant-garde art groups including the Lettrist International, International Movement for an Imaginist Bauhaus, and the London Psychogeographical Association. The manifesto, written by Guy Debord, reinterpreted a Marxist text in advocating revolution in western societies. The group was very involved in the May '68 revolts in Paris - calling for an overthrow of the capitalist labor system.