Loose name for the circle of thinkers associated with the Institute for Social Research, founded in Frankfurt in 1923 and forced into exile by the Nazis. The school's project — Critical Theory, capitalized — was to fuse Marxist analysis with Hegelian philosophy, Freudian psychoanalysis, and empirical social science to diagnose why the expected proletarian revolution had not come in the advanced West and why instead the 20th century had produced fascism, Stalinism, consumer capitalism, and mass culture.
Its first-generation figures — Max Horkheimer, Theodor Adorno, Herbert Marcuse, Walter Benjamin, Erich Fromm, Leo Löwenthal — shared little in method. Horkheimer and Adorno's Dialectic of Enlightenment (1944), written in California wartime exile, is the key early text: Enlightenment rationality, they argued, had turned against itself, producing not emancipation but a totally administered world in which instrumental reason reduces everything — nature, people, art — to material for domination. Adorno's Negative Dialectics (1966) refused the Hegelian move toward synthesis; Herbert Marcuse's One-Dimensional Man (1964) became a canonical text of the 1960s New Left.
The second generation, led by Jürgen Habermas, rebuilt the project on more hopeful foundations: the theory of communicative action. Third-generation figures (Axel Honneth and others) work on recognition, reification, and democratic theory.
The school's influence runs through media studies, Michel Foucault (though he resisted the label), sociology, philosophy of culture, and much of contemporary "critical" X-studies — not always, to the disappointment of its founders, in ways they would have endorsed.