Critical theory (or "social critical theory") describes the neo-Marxist philosophy of the Frankfurt School, which was developed in Germany in the 1930s. Critical theory maintains that ideology is the principal obstacle to human liberation.Martin Jay has stated that the first generation of critical theory is best understood as not promoting a specific philosophical agenda or a specific ideology, but as "a gadfly of other systems".
Critical theory was established as a school of thought primarily by five Frankfurt School theoreticians, Herbert Marcuse, Theodor Adorno, Max Horkheimer, Walter Benjamin, and Erich Fromm, drawing on the critical methods of Karl Marx and Sigmund Freud. Modern critical theory has additionally been influenced by György Lukács and Antonio Gramsci, as well as the second generation Frankfurt School scholars, such as Jürgen Habermas. Concern for social "base and superstructure" is one of the remaining Marxist philosophical concepts in much of the contemporary critical theory. While critical theorists have been frequently defined as Marxist intellectuals, their tendency to denounce some Marxist concepts and to combine Marxian analysis with other sociological and philosophical traditions has resulted in accusations of revisionism by Classical, Orthodox, and Analytical Marxists, and by Marxist-Leninist philosophers.