By Rainer Forst and Klaus Günther.
With Jürgen Habermas, we have lost a scholar without equal and a committed public intellectual who shaped the humanities and social sciences worldwide over many decades. In a lecture at Goethe University Frankfurt marking his 90th birthday, he spoke of three especially happy periods of academic life spent there. Even after his retirement, he remained an active participant in many discussions organized by the Research Centre Normative Orders, and his work was a constant point of reference for our own research. We have lost our most important academic mentor, with whom we remained closely and warmly connected over the years.
In his last major public lecture, “Once Again: On the Relationship Between Morality and Ethical Life,” Habermas revisited the grand philosophies of history developed by Kant, Hegel, and Marx. He returned to the question of reason in history and expressed the hope that – despite all the disappointments events may bring – reason must never abandon the task of improving social conditions.
Habermas turns first to Kant when he insists on the need to clarify our conditions of life through the “public use of reason”: a discourse among all those affected that includes everyone without erasing difference. This is the core theme of his life’s work. Throughout his writings, he pursued the idea of emancipation through communicative reason – a form of reason capable of identifying and overcoming its own blockages, including those produced by social and systemic forces. At the same time, he follows Hegel in arguing that such work must draw on past learning processes for orientation and encouragement. And with Marx, he insists that philosophy and the sciences must not only improve life, but free it from constraints falsely identified as natural and inevitable.
At the close of that memorable lecture, Habermas reflected briefly on the three Frankfurt periods of his academic life: his years as Adorno’s assistant in the late 1950s, his tenure as Horkheimer’s successor in the 1960s, and his return in the 1980s after leading the Max Planck Institute in Starnberg. He described this final phase as “the most fulfilling time of my academic life”, spent in the “free spirit” of Goethe University. We look back on those years with deep gratitude. It was a privilege to learn from him.
In his inaugural Frankfurt lecture in 1965, Habermas expressed a central idea of his philosophy: that the structure of language itself establishes “maturity for us.” He developed this insight in many directions and across disciplinary boundaries. In his habilitation thesis The Structural Transformation of the Public Sphere (1962), he traced the rise of a critical, bourgeois public sphere since the eighteenth century and its later transformation into an increasingly depoliticized sphere shaped by mass media and market forms. Characteristically, Habermas continued to revisit and reinterpret these arguments, most recently in light of digital communication.
Since then, there has hardly been a major theoretical debate in which Jürgen Habermas did not intervene – and in ways that still matter today. Against Gadamer’s hermeneutics, he championed approaches critical of ideology and tradition. During the positivist dispute, he highlighted the distinctive role of critical social sciences, which pursue an emancipatory interest. This culminated in his seminal work Knowledge and Human Interests (1968). In discussions on critical theory, he advocated for a radically democratic and rationalist shift in its premises, guided by the concept of communicative reason. He further developed this concept sociologically in debates with Luhmann’s systems theory, leading to the renowned differentiation between a communicatively structured lifeworld and a system that develops its own media for coordinating actions. These systems tend to overstep their boundaries, drying up and colonizing discursive communication. This is elaborated in his works on the Legitimation Problems of Late Capitalism (1973) and his monumental Theory of Communicative Action (1981), the latter being nothing less than a new theory of modernity and a language-pragmatic transformation of transcendental philosophy. By today’s standards of highly specialized sciences that delve into increasingly narrowly defined fields, this synthesis represents an achievement that remains unparalleled.
The third Frankfurt period, beginning in 1983 after the Starnberg years, saw the development of the distinctly Kantian ethics that became known as discourse ethics. Its roots lay in Habermas’ intensive exchange with his friend and colleague Karl-Otto Apel. In The Philosophical Discourse of Modernity (1985), critique and defense of modernity came together in a way that prepared the ground for what he later called “postmetaphysical thinking.”
For us, as students and collaborators, Between Facts and Norms (1992) was especially formative. It grew out of a legal theory research group established with support from the first Leibniz Prize awarded by the German Research Foundation (DFG), of which we were members. The book shows why the rule of law and democracy are conceptually intertwined. It explains how the tension between human rights and popular sovereignty can be institutionalized so that rights, while presupposed by democratic self-legislation, are specified and – ideally – progressively realized through democratic practice itself. Its theory of deliberative democracy reminds us that what should prevail in a democracy is the better argument, not merely the will of the majority.
In the years that followed, Habermas turned increasingly to a transnational theory of democracy and law – the postnational constellation – with particular attention to Europe (The Crisis of the European Union: A Response). He also addressed the ethical challenges raised by new biotechnologies. These developments prompted the questions of a “derailed secularization” unable to give convincing reasons why genetically optimized human beings should not be created.
Together with the renewed political significance of religion in many parts of the world, this led the postmetaphysical thinker Habermas into a sustained dialogue between theology and philosophy. The result was his vast genealogy of postmetaphysical thought, published in 2019 as Also a History of Philosophy. For Habermas, reason writes its own history from its own standpoint, recognizing that it emerged through successive disputes over faith and must remain open to further learning. As he put it, reason, if fixated on the present alone, “would itself wither away with the disappearance of any thought that transcends what exists in the world as a whole.”
It would take a separate essay to recount Habermas’ many political interventions: from debates in the 1960s on education reform and the student movement, to the controversies of the 1970s over the Radikalenerlass [editor’s note: The Radikalenerlass was a 1970s West German policy that screened public-sector employees for alleged extremist views and barred thousands – especially suspected leftists – from state employment, making it one of the country’s most controversial Cold War-era civil liberties measures], to the 1980s discussions of civil disobedience and the “Historikerstreit” [editor’s note: The Historikerstreit or “historians’ dispute” was a major West German intellectual controversy in the 1980s over how to interpret the Nazi past – especially whether the Holocaust was historically unique or should be compared with other twentieth-century mass crimes], and later debates over reunification, a new constitution, military interventions, bioethics, the pandemic, and most recently the war in Ukraine. Europe remained the constant horizon throughout.
He was particularly troubled by the recent resurgence of nationalism, xenophobia, and antisemitism. In November 2023, together with Nicole Deitelhoff and the two of us, he co-authored a statement opposing antisemitic reactions in Germany to Israel’s military intervention in Gaza. The statement emphasized three guiding principles: “proportionality, the avoidance of civilian casualties, and conducting warfare with the prospect of future peace.” Yet, it was widely criticized by readers who ignored its explicit insistence on those very principles.
Jürgen Habermas will be remembered both as the author of a singular and monumental body of scholarship and as a brilliant political intellectual. To us, he will remain unforgettable as a teacher and caring mentor. His death leaves a void that cannot be filled.
Rainer Forst is Professor of Political Theory and Philosophy and Director of the Research Centre Normative Orders at Goethe University Frankfurt. He studied under Jürgen Habermas, served as his assistant, and completed his doctorate under Habermas in 1993 with a dissertation on theories of justice. Habermas also supported his habilitation on the history and contemporary relevance of tolerance.
Klaus Günther held the chair of Legal Theory, Criminal Law, and Criminal Procedure at Goethe University Frankfurt until March 2026 and will serve as a Goethe Teaching Professor from April onward. He was a member of the legal theory research group founded by Habermas in 1986 with Leibniz Prize funding from the DFG. He completed his doctorate under Habermas with a dissertation on application discourses in morality and law.
