Of significance in the West has been the Marxism of Brazilian educator Paulo Freire. His book Pedagogy of the Oppressed (1972) continues to be an example of how Marxist revolutionary politics can be worked into educational theory and practice. This kind of education has become known as critical (sometimes dialogical) pedagogy and it involves teachers using classrooms for a critique of bourgeois ideology or the worldviews of the oppressors. The views of the oppressed themselves, the students, are given a voice and a legitimacy. They are not suppressed by a dominant teacher who tells them ‘how it is’ and ‘what they must do’. Instead teachers and students seek to challenge traditional models of their relationship, working through together in a mutual dialogue how the world is and naming it according to these suppressed interpretations. For Freire this praxis is revolutionary because the ideas, language and concepts of the oppressed will threaten and potentially overcome the bourgeois relations of domination, both in education and in the wider society. At its root, this critical education aims to undermine bourgeois ideology and to transform undemocratic forms of society into free and democratic socialist societies. Critical pedagogy has enjoyed a vitality in the West, particularly in North America, although there are other strains, most notably in Europe from the critical theory of Horkheimer, Adorno and Habermas. A particular tension in this strain of critical pedagogy, given its origins, is that it concentrates very heavily on the ideological and other obstacles which block revolutionary change, offering a somewhat negative and pessimistic diagnosis. Habermas alone is held to be one critical theorist who maintains a more optimistic vision (see, for example, his two volume book, The Theory of Communicative Action, and R.E. Young’s A Critical Theory of Education: Habermas and our Children’s Future).