Marxist philosophy or Marxist theory are terms that cover work in philosophy that is strongly influenced by Karl Marx's materialist approach to theory or that is written by Marxists. It may be broadly divided into Western Marxism, which drew out of various sources, and the official philosophy in the Soviet Union, which enforced a rigid reading of Marx called dialectical materialism, in particular during the 1930s.
The phrase "Marxist philosophy" itself does not indicate a strictly defined sub-field of philosophy, because the diverse influence of Marxist theory has extended into fields as varied as aesthetics, ethics, ontology, epistemology, theoretical psychology and philosophy of science, as well as its obvious influence on political philosophy and the philosophy of history. The key characteristics of Marxism in philosophy are its materialism and its commitment to political practice as the end goal of all thought.
Political philosophy is the study of such topics as politics, liberty, justice, property, rights, law, and the enforcement of a legal code by authority: what they are, why (or even if) they are needed, what, if anything, makes a government legitimate, what rights and freedoms it should protect and why, what form it should take and why, what the law is, and what duties citizens owe to a legitimate government, if any, and when it may be legitimately overthrown, if ever. In a vernacular sense, the term "political philosophy" often refers to a general view, or specific ethic, political belief or attitude, about politics that does not necessarily belong to the technical discipline of philosophy. In short, political philosophy is the activity, as with all philosophy, whereby the conceptual apparatus behind such concepts as aforementioned are analyzed, in their history, intent, evolution and the like.
Critical theory is a school of thought that stresses the reflective assessment and critique of society and culture by applying knowledge from the social sciences and the humanities. As a term, critical theory has two meanings with different origins and histories: the first originated in sociology and the second originated in literary criticism, whereby it is used and applied as an umbrella term that can describe a theory founded upon critique; thus, the theorist Max Horkheimer described a theory as critical insofar as it seeks "to liberate human beings from the circumstances that enslave them."
In philosophy, the term critical theory describes the neo-Marxist philosophy of the Frankfurt School, which was developed in Germany in the 1930s. Frankfurt theorists drew on the critical methods of Karl Marx and Sigmund Freud. Critical theory maintains that ideology is the principal obstacle to human liberation. 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. Modern critical theory has been influenced by György Lukács and Antonio Gramsci as well as the second generation Frankfurt School scholars, including Jürgen Habermas. In Habermas's work, critical theory transcended its theoretic roots in German idealism, and progressed closer to American pragmatism. Concern for social "base and superstructure" is one of the remaining Marxist philosophic concepts in much of the contemporary critical theory.