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Hermann Cohen (1842–1918)

Cohen founded the Marburg school of neo-Kantianism — the tradition that read Kant not as setting limits to knowledge but as revealing the constitutive role of thought in producing experience. Where Kant had asked what the conditions of possible experience are, Cohen shifted the emphasis: thought does not merely organise given experience; it generates the object of knowledge. The “given” — raw sensory data waiting to be shaped by the categories — disappears in Cohen’s reading; what remains is the productive activity of thought, which constitutes its objects through logical operations. The shift made Kant a philosopher of science (the categories are the formal conditions of mathematical natural science, not of ordinary perception) and set the terms for Cassirer’s extension into symbolic forms and for the broader neo-Kantian influence on twentieth-century philosophy of science. Cohen was also a major figure in German Jewish intellectual life, developing a philosophy of religion that argued for the ethical core of Judaism and its compatibility with the ideals of the German Enlightenment.

Life

Born 4 July 1842 in Coswig (Anhalt), Germany, the son of a cantor in a Jewish community. Educated at the Jewish Theological Seminary of Breslau and at the universities of Breslau, Berlin, and Halle. PhD from the University of Halle (1865). His early work was on Kant’s theory of experience, published as Kants Theorie der Erfahrung (Kant’s Theory of Experience, 1871) — the book that established his interpretation and launched the Marburg school.

Appointed professor of philosophy at the University of Marburg (1876), where he remained until 1912. The Marburg years were his most productive and influential. He built the Marburg school into one of the two dominant neo-Kantian traditions in German philosophy (the other being the Southwest or Baden school, led by Wilhelm Windelband and Heinrich Rickert). His most important intellectual heir was Cassirer; Paul Natorp, whom Cohen brought to Marburg, became his junior colleague and co-leader of the school. Cohen’s constitutive reading of Kant was the position that Heidegger — who held a chair at Marburg from 1923 to 1928, years after Cohen’s departure — argued against through Cassirer at the 1929 Davos debate.

After retiring from Marburg, Cohen moved to Berlin and taught at the Hochschule für die Wissenschaft des Judentums (Academy for the Science of Judaism) (1912–18), where he devoted his last years to the philosophy of religion. Religion der Vernunft aus den Quellen des Judentums (Religion of Reason Out of the Sources of Judaism, 1919, posthumous) was the culmination of this work. Died 4 April 1918 in Berlin.

The logic of pure cognition

Cohen’s philosophical system is developed across three “critiques” that parallel Kant’s: the Logik der reinen Erkenntnis (Logic of Pure Cognition, 1902), the Ethik des reinen Willens (Ethics of Pure Will, 1904), and the Ästhetik des reinen Gefühls (Aesthetics of Pure Feeling, 1912).

The productive role of thought. Cohen’s central move is the elimination of the Kantian “given” — the sensory manifold that, in Kant’s framework, is received passively and then organised by the categories. For Cohen, there is no givenness prior to thought. Thought is productive: it generates its objects through the logical operations that constitute the scientific method. The object of knowledge is not a thing encountered; it is a product of the method by which knowledge is achieved. Mathematics, for Cohen, is the paradigm: mathematical objects are constituted by the operations that define them, not discovered as pre-existing entities.

The infinitesimal. Cohen gave a central role to the infinitesimal calculus as the model for the productive activity of thought. The infinitesimal is not a thing but an operation — the limit of a process of division that produces the object (the derivative, the integral) through the process itself. Cohen saw in this the structure of thought’s productivity: thought generates its objects not by representing something already there but by performing the operations that bring the object into being. The interpretation was contested by mathematicians (it does not correspond to modern rigorous treatments of the calculus), but as a philosophical model for the productive character of thought it was influential within the Marburg school.

Science as the model. Cohen’s neo-Kantianism takes mathematical natural science — not ordinary perception — as the paradigm of knowledge. The categories are not the conditions of everyday experience (seeing tables, hearing sounds) but the formal conditions of scientific theory-construction. This narrows Kant’s scope but sharpens it: Cohen’s question is not “How is experience in general possible?” but “How is mathematical physics possible?” — and the answer is that thought produces the objects of physics through the logical and mathematical operations that constitute physical theory.

Ethics and Judaism

Cohen’s ethics is Kantian in structure — duty, autonomy, the moral law — but with a social and political dimension that Kant’s ethics does not emphasise. The Ethik des reinen Willens argues that the moral subject is not the isolated individual but the legal person within a community. The state, on Cohen’s account, is the ethical community in its institutional form; socialism (which Cohen understood as ethical, not materialist) is the political expression of the Kantian moral law applied to economic and social relations. Cohen’s ethical socialism was influential in the German Social Democratic Party and in the broader tradition of Kantian left politics.

Religion of Reason Out of the Sources of Judaism (1919) argues that Judaism, properly understood, is a religion of ethical monotheism — that its core is the moral relationship between the individual and God, mediated by the ethical demand for justice. The book is not a work of theology but of philosophy: Cohen reads the Jewish sources (the Hebrew Bible, the Talmud, Maimonides) as expressions of a philosophical position — the primacy of ethics, the uniqueness of God as the ground of morality, the messianic idea as the regulative ideal of a just future. The work was his most personal and has had a lasting influence on modern Jewish philosophy, particularly on Franz Rosenzweig and Emmanuel Levinas.

Where Cohen stops

The elimination of the given is Cohen’s most powerful and most contested move. If thought produces its objects entirely through its own operations, what constrains thought? What prevents the system from becoming self-enclosed — a logical machine that generates objects without contact with anything outside itself? Cohen’s answer is that mathematical natural science provides the constraint: the operations of thought are accountable to the methods and results of the sciences. But this answer pushes the question one level up: what constrains the sciences? If the answer is “thought’s own operations,” the circle closes. The problem of the given — whether knowledge requires some input that thought does not produce — was the point on which the Marburg programme was challenged by the Southwest neo-Kantians, by Husserl’s phenomenology (which insisted on the givenness of phenomena), and later by the analytic tradition.

Cassirer transformed Cohen’s programme rather than continuing it. The move from the logic of pure cognition (thought constitutes the objects of science) to the philosophy of symbolic forms (multiple symbolic activities — language, myth, art, science — constitute multiple domains of experience) broadened Cohen’s framework beyond recognition. Cohen’s system is monistic — thought is one, and science is its paradigm; Cassirer’s is pluralist — there are many constitutive symbolic forms, and science is one among them. Whether Cassirer’s extension preserves what was distinctive about Cohen or departs from it is debated in the literature on Marburg neo-Kantianism. What is clear is that without Cohen’s constitutive reading of Kant — the insistence that thought produces rather than discovers — the symbolic-forms project would not have been conceivable.

Key works

See also: Cassirer · Kant · Husserl