Jurgen Habermas (born June 18, 1929) is a German philosopher and sociologist in the tradition of critical theory and American pragmatism. He is perhaps best known for his work on the concept of the public sphere, the topic (and title) of his first book. His work focused on the foundations of social theory and epistemology, the analysis of advanced capitalistic societies and democracy, the rule of law in a critical social-evolutionary context, and contemporary politics—particularly German politics. Habermas's theoretical system is devoted to revealing the possibility of reason, emancipation, and rational-critical communication latent in modern institutions and in the human capacity to deliberate and pursue rational interests. Habermas was born in Düsseldorf, North Rhine-Westphalia. Until his graduation from gymnasium, Habermas lived in Gummersbach, near Cologne. His father, Ernst Habermas, was executive director of the Cologne Chamber of Industry and Commerce, and was described by Habermas as a Nazi sympathizer. He was brought up in a staunchly Protestant milieu, his grandfather being the director of the seminary in Gummersbach. He studied at the universities of Göttingen (1949/50), Zürich (1950/51), and Bonn (1951–54) and earned a doctorate in philosophy[1] from Bonn in 1954 with a dissertation entitled, Das Absolute und die Geschichte. Von der Zwiespältigkeit in Schellings Denken ("The absolute and history: on the contradiction in Schelling's thought"). His dissertation committee included Erich Rothacker and Oskar Becker. From 1956 on, he studied philosophy and sociology under the critical theorists Max Horkheimer and Theodor Adorno at the Johann Wolfgang Goethe University Frankfurt am Main Institute for Social Research, but because of a rift between the two over his dissertation—Horkheimer had made unacceptable demands for revision—as well as his own belief that the Frankfurt School had become paralyzed with political skepticism and disdain for modern culture—he finished his habilitation in political science at the University of Marburg under the Marxist Wolfgang Abendroth. His habilitation work was entitled, Strukturwandel der Öffentlichkeit; Untersuchungen zu einer Kategorie der Bürgerlichen Gesellschaft (published in English translation in 1989 as The Structural Transformation of the Public Sphere: an Inquiry into a Category of Bourgeois Society). In 1961, he became a privatdozent in Marburg, and—in a move that was highly unusual for the German academic scene of that time—he was offered the position of "extraordinary professor" (professor without chair) of philosophy at the University of Heidelberg (at the instigation of Hans-Georg Gadamer and Karl Löwith) in 1962, which he accepted. In 1964, strongly supported by Adorno, Habermas returned to Frankfurt to take over Horkheimer's chair in philosophy and sociology. He accepted the position of Director of the Max Planck Institute in Starnberg (near Munich) in 1971, and worked there until 1983, two years after the publication of his magnum opus, The Theory of Communicative Action. Habermas then returned to his chair at Frankfurt and the directorship of the Institute for Social Research. Since retiring from Frankfurt in 1993, Habermas has continued to publish extensively. In 1986, he received the Gottfried Wilhelm Leibniz Prize of the Deutsche Forschungsgemeinschaft, which is the highest honour awarded in German research. He also holds the uncharacteristically postmodern position of "Permanent Visiting" Professor at Northwestern University in Evanston, Illinois, and "Theodor Heuss Professor" at The New School, New York. Habermas was awarded The Prince of Asturias Award in Social Sciences of 2003. Habermas was also the 2004 Kyoto Laureate in the Arts and Philosophy section. He traveled to San Diego and on March 5, 2005, as part of the University of San Diego's Kyoto Symposium, gave a speech entitled The Public Role of Religion in Secular Context, regarding the evolution of separation of Church and State from neutrality to intense secularism. He received the 2005 Holberg International Memorial Prize (about € 520,000). Habermas was famous as a teacher and mentor. Among his most prominent students were the pragmatic philosopher Herbert Schnädelbach (theorist of discourse distinction and rationality), the political sociologist Claus Offe (professor at the Hertie School of Governance in Berlin) , the social philosopher Johann Arnason (professor at La Trobe University and chief editor of the journal Thesis Eleven), the sociological theorist Hans Joas (professor at the University of Erfurt and at the University of Chicago), the theorist of societal evolution Klaus Eder, the social philosopher Axel Honneth (the current director of the Institute for Social Research), the American philosopher Thomas McCarthy, the co-creator of mindful inquiry in social research Jeremy J. Shapiro, and the assassinated Serbian prime minister Zoran Đinđić.   Habermas constructed a comprehensive framework of social theory and philosophy drawing on a number of intellectual traditions: the German philosophical thought of Immanuel Kant, Friedrich Schelling, G. W. F. Hegel, Wilhelm Dilthey, Edmund Husserl, and Hans-Georg Gadamer the Marxian tradition — both the theory of Karl Marx himself as well as the critical neo-Marxian theory of the Frankfurt School, i.e. Max Horkheimer, Theodor Adorno, and Herbert Marcuse the sociological theories of Max Weber, Émile Durkheim, and George Herbert Mead the linguistic philosophy and speech act theories of Ludwig Wittgenstein, J.L. Austin, P. F. Strawson, Stephen Toulmin and John Searle the developmental psychology of Jean Piaget and Lawrence Kohlberg the American pragmatist tradition of Charles Sanders Peirce and John Dewey the sociological social systems theory of Talcott Parsons and Niklas Luhmann Neo-Kantian thought Jürgen Habermas considered his major achievement to be the development of the concept and theory of communicative reason or communicative rationality, which distinguishes itself from the rationalist tradition by locating rationality in structures of interpersonal linguistic communication rather than in the structure of either the cosmos or the knowing subject. This social theory advances the goals of human emancipation, while maintaining an inclusive universalist moral framework. This framework rests on the argument called universal pragmatics - that all speech acts have an inherent telos (the Greek word for "end") — the goal of mutual understanding, and that human beings possess the communicative competence to bring about such understanding. Habermas built the framework out of the speech-act philosophy of Ludwig Wittgenstein, J. L. Austin, and John Searle, the sociological theory of the interactional constitution of mind and self of George Herbert Mead, the theories of moral development of Jean Piaget and Lawrence Kohlberg, and the discourse ethics of his Heidelberg colleague Karl-Otto Apel. He carried forward the traditions of Kant and the Enlightenment and of democratic socialism through his emphasis on the potential for transforming the world and arriving at a more humane, just, and egalitarian society through the realization of the human potential for reason, in part through discourse ethics. While Habermas conceded that the Enlightenment is an "unfinished project," he argued it should be corrected and complemented, not discarded. In this he distanced himself from the Frankfurt School, criticizing it, as well as much of postmodernist thought, for excessive pessimism, misdirected radicalism and exaggerations. Within sociology, Habermas's major contribution was the development of a comprehensive theory of societal evolution and modernization focusing on the difference between communicative rationality and rationalization on the one hand and strategic/instrumental rationality and rationalization on the other. This included a critique from a communicative standpoint of the differentiation-based theory of social systems developed by Niklas Luhmann, a student of Talcott Parsons. His defence of modernity and civil society has been a source of inspiration to others, and is considered a major philosophical alternative to the varieties of poststructuralism. He has also offered an influential analysis of late capitalism. Habermas saw the rationalization, humanization, and democratization of society in terms of the institutionalization of the potential for rationality that is inherent in the communicative competence that is unique to the human species. Habermas believed communicative competence has developed through the course of evolution, but in contemporary society it is often suppressed or weakened by the way in which major domains of social life, such as the market, the state, and organizations, have been given over to or taken over by strategic/instrumental rationality, so that the logic of the system supplants that of the lifeworld.   Habermas introduces the concept of “reconstructive science” with a double purpose: to place the “general theory of society” between philosophy and social science and re-establish the rift between the “great theorization” and the “empirical research”. The model of “rational reconstructions” represents the main thread of the surveys about the “structures” of the world of life (“culture”, “society” and “personality”) and their respective “functions” (cultural reproductions, social integrations and socialization). For this purpose, the dialectics between “symbolic representation” of “the structures subordinated to all worlds of life” (“internal relationships”) and the “material reproduction” of the social systems in their complex (“external relationships” between social systems and environment) has to be considered. This model finds an application, above all, in the “theory of the social evolution”, starting from the reconstruction of the necessary conditions for a phylogeny of the socio-cultural life forms (the “hominization”) until an analysis of the development of “social formations”, which Habermas subdivides into primitive, traditional, modern and contemporary formations. This paper is an attempt, primarily, to formalize the model of “reconstruction of the logic of development” of “social formations” summed up by Habermas through the differentiation between vital world and social systems (and, within them, through the “rationalization of the world of life” and the “growth in complexity of the social systems”). Secondly, it tries to offer some methodological clarifications about the “explanation of the dynamics” of “historical processes” and, in particular, about the “theoretical meaning” of the evolutional theory’s propositions. Even if the German sociologist considers that the “ex-post rational reconstructions” and “the models system/environment” cannot have a complete “historiographical application”, these certainly act as a general premise in the argumentative structure of the “historical explanation”.