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Critical theory is a social philosophy pertaining to the reflective assessment and critique of society and culture in order to reveal and challenge power structures. With origins in sociology, as well as in literary criticism, it argues that social problems are influenced and created more by societal structures and cultural assumptions than by individual and psychological factors. Maintaining that ideology is the principal obstacle to human liberation,  critical theory was established as a school of thought primarily by the Frankfurt School theoreticians Herbert Marcuse, Theodor Adorno, Walter Benjamin, Erich Fromm, and Max Horkheimer. The latter sociologist described a theory as critical insofar as it seeks "to liberate human beings from the circumstances that enslave them." 
In sociology and political philosophy, the term Critical Theory describes the Western-Marxist philosophy of the Frankfurt School, which was developed in Germany in the 1930s and draws on the ideas of Karl Marx and Sigmund Freud  . Though a "critical theory" or a "critical social theory" may have similar elements of thought, the capitalization of Critical Theory as if it were a proper noun particularly stresses the intellectual lineage specific to the Frankfurt School. 
Modern critical theory has additionally been influenced by György Lukács and Antonio Gramsci, as well as second-generation Frankfurt School scholars, notably Jürgen Habermas. In Habermas' work, critical theory transcended its theoretical roots in German idealism and progressed closer to American pragmatism. Concern for social "base and superstructure" is one of the remaining Marxist philosophical concepts in much of contemporary critical theory.  :5–8
Postmodern critical theory analyzes the fragmentation of cultural identities in order to challenge modernist-era constructs such as metanarratives, rationality, and universal truths, while politicizing social problems "by situating them in historical and cultural contexts, to implicate themselves in the process of collecting and analyzing data, and to relativize their findings." 
Critical theory (German: Kritische Theorie) was first defined by Max Horkheimer of the Frankfurt School of sociology in his 1937 essay "Traditional and Critical Theory", in which it is described as a social theory oriented toward critiquing and changing society as a whole, in contrast to traditional theory oriented only to understanding or explaining it. Wanting to distinguish critical theory as a radical, emancipatory form of Marxist philosophy, Horkheimer critiqued both the model of science put forward by logical positivism, and what he and his colleagues saw as the covert positivism and authoritarianism of orthodox Marxism and Communism. He described a theory as critical insofar as it seeks "to liberate human beings from the circumstances that enslave them."  Critical theory involves a normative dimension, either through criticizing society from some general theory of values, norms (or oughts), or through criticizing it in terms of its own espoused values (i.e. immanent critique). 
The core concepts of critical theory are that it should:
This version of "critical" theory derives from the use of the term critique by Immanuel Kant (18th century), in his Critique of Pure Reason; and Marx (19th century), through the concept that his Das Kapital forms a "critique of political economy."
For Kant's transcendental idealism, critique means examining and establishing the limits of the validity of a faculty, type, or body of knowledge, especially through accounting for the limitations imposed by the fundamental, irreducible concepts in use in that knowledge system.
Kant's notion of critique has been associated with the overturning of false, unprovable, or dogmatic philosophical, social, and political beliefs. His critique of reason involved the critique of dogmatic theological and metaphysical ideas, and was intertwined with the enhancement of ethical autonomy and the Enlightenment critique of superstition and irrational authority. Ignored by many in "critical realist" circles, however, is that Kant's immediate impetus for writing his Critique of Pure Reason was to address problems raised by David Hume's skeptical empiricism which, in attacking metaphysics, employed reason and logic to argue against the knowability of the world and common notions of causation. Kant, by contrast, pushed the employment of a priori metaphysical claims as requisite, for if anything is to be said to be knowable, it would have to be established upon abstractions distinct from perceivable phenomena.
Marx explicitly developed the notion of critique into the critique of ideology, linking it with the practice of social revolution, as stated in the eleventh section of his famous Theses on Feuerbach: "The philosophers have only interpreted the world, in various ways; the point is to change it." 
One of the distinguishing characteristics of critical theory, as Adorno and Horkheimer elaborated in their Dialectic of Enlightenment (1947), is a certain ambivalence concerning the ultimate source or foundation of social domination, an ambivalence which gave rise to the "pessimism" of the new critical theory over the possibility of human emancipation and freedom.  This ambivalence was rooted, of course, in the historical circumstances in which the work was originally produced, particularly the rise of National Socialism, state capitalism, and culture industry as entirely new forms of social domination that could not be adequately explained within the terms of traditional Marxist sociology.  
For Adorno and Horkheimer, state intervention in economy had effectively abolished the tension between the "relations of production" and "material productive forces of society," a tension which, according to traditional critical theory, [clarification needed] constituted the primary contradiction within capitalism. The market (as an "unconscious" mechanism for the distribution of goods) had been replaced by centralized planning. 
Yet, contrary to Marx's famous prediction in the Preface to a Contribution to the Critique of Political Economy, this shift did not lead to "an era of social revolution," but rather to fascism and totalitarianism. As such, critical theory was left, in Jürgen Habermas' words, without "anything in reserve to which it might appeal, and when the forces of production enter into a baneful symbiosis with the relations of production that they were supposed to blow wide open, there is no longer any dynamism upon which critique could base its hope."  For Adorno and Horkheimer, this posed the problem of how to account for the apparent persistence of domination in the absence of the very contradiction that, according to traditional critical theory, was the source of domination itself.
In the 1960s, Jürgen Habermas, a proponent of critical social theory,  raised the epistemological discussion to a new level in his Knowledge and Human Interests (1968), by identifying critical knowledge as based on principles that differentiated it either from the natural sciences or the humanities, through its orientation to self-reflection and emancipation.  Although unsatisfied with Adorno and Horkheimer's thought presented in Dialectic of Enlightenment, Habermas shares the view that, in the form of instrumental rationality, the era of modernity marks a move away from the liberation of enlightenment and toward a new form of enslavement.  :6 In Habermas's work, critical theory transcended its theoretical roots in German idealism, and progressed closer to American pragmatism.
Habermas is now influencing the philosophy of law in many countries—for example the creation of the social philosophy of law in Brazil—and his theory also has the potential to make the discourse of law one important institution of the modern world as a heritage of the Enlightenment. 
His ideas regarding the relationship between modernity and rationalization are in this sense strongly influenced by Max Weber. Habermas dissolved further the elements of critical theory derived from Hegelian German Idealism, although his thought remains broadly Marxist in its epistemological approach. Perhaps his two most influential ideas are the concepts of the public sphere and communicative action; the latter arriving partly as a reaction to new post-structural or so-called "postmodern" challenges to the discourse of modernity. Habermas engaged in regular correspondence with Richard Rorty and a strong sense of philosophical pragmatism may be felt in his theory; thought which frequently traverses the boundaries between sociology and philosophy.
Focusing on language, symbolism, communication, and social construction, critical theory has been applied within the social sciences as a critique of social construction and postmodern society. 
While modernist critical theory (as described above) concerns itself with "forms of authority and injustice that accompanied the evolution of industrial and corporate capitalism as a political-economic system," postmodern critical theory politicizes social problems "by situating them in historical and cultural contexts, to implicate themselves in the process of collecting and analyzing data, and to relativize their findings."  Meaning itself is seen as unstable due to the rapid transformation in social structures. As a result, the focus of research is centered on local manifestations, rather than broad generalizations.
Postmodern critical research is also characterized by the crisis of representation, which rejects the idea that a researcher's work is an "objective depiction of a stable other." Instead, many postmodern scholars have adopted "alternatives that encourage reflection about the 'politics and poetics' of their work. In these accounts, the embodied, collaborative, dialogic, and improvisational aspects of qualitative research are clarified." 
The term critical theory is often appropriated when an author works within sociological terms, yet attacks the social or human sciences, thus attempting to remain "outside" those frames of inquiry. Michel Foucault has been described as one such author.  Jean Baudrillard has also been described as a critical theorist to the extent that he was an unconventional and critical sociologist;  this appropriation is similarly casual, holding little or no relation to the Frankfurt School.  In contrast, Jürgen Habermas of The Frankfurt School is one of the key critics of postmodernism. 
From the 1960s and 1970s onward, language, symbolism, text, and meaning came to be seen as the theoretical foundation for the humanities, through the influence of Ludwig Wittgenstein, Ferdinand de Saussure, George Herbert Mead, Noam Chomsky, Hans-Georg Gadamer, Roland Barthes, Jacques Derrida and other thinkers in linguistic and analytic philosophy, structural linguistics, symbolic interactionism, hermeneutics, semiology, linguistically-oriented psychoanalysis (Jacques Lacan, Alfred Lorenzer), and deconstruction. 
When, in the 1970s and 1980s, Jürgen Habermas redefined critical social theory as a study of communication, with communicative competence and communicative rationality on the one hand, and distorted communication on the other. The two versions of critical theory began to overlap to a much greater degree than before. 
Critical theorists have widely credited Paulo Freire for the first applications of critical theory towards education/pedagogy, considering his best-known work to be Pedagogy of the Oppressed, a seminal text in what is now known as the philosophy and social movement of critical pedagogy.   Dedicated to the oppressed and based on his own experience helping Brazilian adults to read and write, Freire includes a detailed Marxist class analysis in his exploration of the relationship between the colonizer and the colonized. In the book, Freire calls traditional pedagogy the "banking model of education," because it treats the student as an empty vessel to be filled with knowledge, like a piggy bank. He argues that pedagogy should instead treat the learner as a co-creator of knowledge.
In contrast to the banking model, the teacher in the critical-theory model is not dispenser of all knowledge, the sage on a stage, but a participant who learns with and from the students—in conversation with them; even as they are learning from the teacher. The goal is to liberate the learner from an oppressive construct of teacher versus student, a dichotomy analogous to colonizer and colonized. It is not enough for the student to analyze societal power structures and hierarchies, to merely recognize imbalance and inequity; critical theory pedagogy must also empower the learner to both reflect and act on that reflection to challenge an oppressive status quo. 
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. 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 has been criticized for not offering any clear road map to political action (praxis) following critique, often explicitly repudiating any solutions (such as with Herbert Marcuse's "the Great Refusal", which promoted abstaining from engaging in active political change). 
A primary criticism of the theory is that it is anti-scientific, both for its lack of the use of the scientific method, and for its overt criticism of science as a tool used for oppression of marginalized groups of people. 
- Geuss, R. The Idea of a Critical Theory. Cambridge: Cambridge University Press. ch. 4. ^
- (Horkheimer 1982, 244) ^
- Outhwaite, William.  2009. Habermas: Key Contemporary Thinkers (2nd ed.). ISBN 978-0-7456-4328-1. ^
- Lindlof, Thomas R.; Taylor, Bryan C. (2002). Qualitative Communication Research Methods. SAGE. p. 49. ISBN 9780761924944. forms of authority and injustice that accompanied the evolution of industrial and corporate capitalism as a political-economic system. ^
- Horkheimer 1982, p. 244. ^
- Bohman, James (1 January 2016). Zalta, Edward N. (ed.). The Stanford Encyclopedia of Philosophy (Fall 2016 ed.). Metaphysics Research Lab, Stanford University. ^
- "Theses on Feuerbach". §XI. Marxists Internet Archive. Retrieved 11 April 2015.CS1 maint: others (link) ^
- Adorno, Theodor W., and Max Horkheimer.  2002. Dialectic of Enlightenment, translated by E. Jephcott. Stanford: Stanford University Press. p. 242. ^
- Habermas, Jürgen. 1987. "The Entwinement of Myth and Enlightenment: Horkheimer and Adorno." In The Philosophical Discourse of Modernity: Twelve Lectures, translated by F. Lawrence. Cambridge, MA: MIT Press. p. 116:"Critical Theory was initially developed in Horkheimer's circle to think through political disappointments at the absence of revolution in the West, the development of Stalinism in Soviet Russia, and the victory of fascism in Germany. It was supposed to explain mistaken Marxist prognoses, but without breaking Marxist intentions." ^
- Dubiel, Helmut. 1985. Theory and Politics: Studies in the Development of Critical Theory, translated by B. Gregg. Cambridge, MA. ^
- Dialectic of Enlightenment. p. 38: " [G] one are the objective laws of the market which ruled in the actions of the entrepreneurs and tended toward catastrophe. Instead the conscious decision of the managing directors executes as results (which are more obligatory than the blindest price-mechanisms) the old law of value and hence the destiny of capitalism." ^
- "The Entwinement of Myth and Enlightenment," p. 118. ^
- Katsiaficas, George N., Robert George Kirkpatrick, and Mary Lou Emery. 1987. Introduction to Critical Sociology. Irvington Publishers. p. 26. ^
- Laurie, Timothy, Hannah Stark, and Briohny Walker. 2019. "Critical Approaches to Continental Philosophy: Intellectual Community, Disciplinary Identity, and the Politics of Inclusion." Parrhesia 30:1–17. doi:10.1007/s10691-011-9167-4. (Discusses critical social theory as a form of self-reflection.) ^
- Bittar, Eduardo C. B. 2013. Democracia, Justiça e Emancipação Social. São Paulo: Quartier Latin. ^
- Agger, Ben (2012), "Ben Agger", North American Critical Theory After Postmodernism, Palgrave Macmillan UK, pp. 128–154, doi:10.1057/9781137262868_7, ISBN 9781349350391 ^
- Lindlof & Taylor, 2002, p. 53 ^
- Rivera Vicencio, E. (2012). "Foucault: His influence over accounting and management research. Building of a map of Foucault's approach". International Journal of Critical Accounting. 4 (5/6): 728–756. doi:10.1504/IJCA.2012.051466. ^
- "Introduction to Jean Baudrillard, Module on Postmodernity". www.cla.purdue.edu. Retrieved 16 June 2017. ^
- Kellner, Douglas (2015). Zalta, Edward N. (ed.). The Stanford Encyclopedia of Philosophy (Winter 2015 ed.). Metaphysics Research Lab, Stanford University. ^
- Aylesworth, Gary (2015). "Postmodernism". The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University. Retrieved 24 June 2017. ^
- "Paulo Freire's Pedagogy of the Oppressed : Book Summary". The Educationist. 9 July 2014. Retrieved 4 June 2020. ^
- For a history of the emergence of critical theory in the field of education, see Gottesman, Isaac. 2016. The Critical Turn in Education: From Marxist Critique to Postructuralist Feminism to Critical Theories of Race. New York: Routledge. ^
- "Paulo Freire's Pedagogy of the Oppressed : Book Summary". The Educationist. 9 July 2014. Retrieved 4 June 2020. ^
- See, e.g., Kołakowski, Leszek.  1979. Main Currents of Marxism 3. W. W. Norton & Company. ISBN 0393329437. ch. 10. ^
- Jay, Martin (1996). The Dialectical Imagination: A History of the Frankfurt School and the Institute of Social Research, 1923–1950. University of California Press. p. 41. ISBN 978-0-520-20423-2. ^
- Corradetti, Claudio. "The Frankfurt School and Critical Theory." Internet Encyclopedia of Philosophy. ^
- "How Critical Theory Came to Be Skeptical of Science". Areo. 12 February 2020. Retrieved 29 July 2020. ^