The main philosophical work of Samuel Hirsch (1815–89), titled Die Religionsphilosophie der Juden (“The Philosophy of Religion of the Jews”), was decisively influenced by G.W.F. Hegel (1770–1831). Hegel’s impact is most evident in Hirsch’s method and in the task that he assigned to the philosophy of religion—the transformation of religious consciousness into conceptual truth. Contrary to Hegel, however, he did not consider religious truth to be inadequate compared with philosophical truth.

In Hirsch’s view, God revealed himself in the first stages of Jewish history by means of miracles and prophecy. At present, he manifests himself in the miracle of the existence of the Jewish people. Hirsch further maintained that Christianity and Judaism were identical at the time of Jesus and that a decisive break between them was caused by Paul the Apostle. When the Pauline elements are eliminated from Christianity, it will be essentially in agreement with Judaism, though Judaism will preserve its separate existence.

Nachman Krochmal

Nachman Krochmal (1785–1840), a native of Galicia (at that time part of Austria), wrote the highly influential Hebrew treatise More nevukhe ha-zman (“Guide for the Perplexed for Our Time”), on the philosophy of history and on Jewish history. Krochmal’s philosophical thought was based on the notion of spirit. He was mainly concerned with the “national spirit” that is proper to each people and that accounts for the characteristics differentiating one people from another in every domain of human activity. The national spirits of all peoples except the Jewish are, according to Krochmal, essentially particular. Hence, when the nation becomes extinct, the national spirit either disappears or, if it is powerful, is assimilated by some other nation. The perpetuity of the Jewish people, according to Krochmal, is the result of their special relation to the Universal Spirit, who is the God of Israel.

Solomon Steinheim

Solomon Ludwig Steinheim (1789–1866), the author of Die Offenbarung nach dem Lehrbegriff der Synagoge (“The Revelation According to the Doctrine of the Synagogue”), was apparently influenced by the antirationalism of the German philosopher Friedrich Heinrich Jacobi (1743–1819). His criticism of science is based on Jacobi’s work, though he did not agree with Jacobi in opposing discursive reason to the intuitive knowledge of God; Steinheim contrasted human reason with divine revelation. The main point of opposition between revelation, vouchsafed to the prophets of Israel, and reason is that the God posited by reason is subject to necessity—he can act only in accordance with laws. Moreover, reason affirms that nothing can come from nothing. Accordingly, God is free to create not a good world but only the best possible world. Revealed religion, on the other hand, affirms the freedom of God and the creation of the world out of nothing.

Hermann Cohen

There seems to be little connection between the Jewish philosophers of the first half or two-thirds of the 19th century and Hermann Cohen (1842–1918), the head of the Neo-Kantian school centred at the University of Marburg. Cohen may be regarded as a rather unusual case among the Jewish philosophers of his and the preceding generations because of the dual nature of his philosophical thought—the general and the Jewish—and the uneasy equilibrium between them. Judaism was by no means the only important theme of his philosophical system; indeed, it was not even his point of departure. For most of his life, Cohen was wholly committed to his brand of Kantianism, and he displayed considerable originality in its elaboration. It has been maintained with some justification that his doctrine manifests a certain (unintentional) kinship with Hegel’s, though Cohen’s idea of God is based on an analysis and development of certain conceptions of Immanuel Kant. In Cohen’s view, reason requires that nature be conceived of as conforming to a single rational plan and that there be harmony between the domains of natural and moral teleology (ultimate purposes or ends). These two requirements in turn require the adoption of the idea of God—the word idea being used in the Kantian sense, which means that no assertion is made about the metaphysical reality of God.

Cohen’s later works increasingly emphasized generally religious and specifically Judaic elements. Some scholars, most notably his student Franz Rosenzweig, interpreted this as a major turn in Cohen’s thought. In the late 20th century, however, most scholars held that the more-pronounced Judaism in Cohen’s later works was the culmination of his overall philosophical system, not a radical departure from it.

Franz Rosenzweig

Franz Rosenzweig (1886–1929) published his main philosophical work, Der Stern der Erlösung (The Star of Redemption), in 1921. It begins by rejecting the traditional philosophical denial of the fear of death, maintaining instead that this fear is the beginning of the cognition of the All. Humans should fear death, despite the indifference of philosophy and its predilection for accepting death. Traditional philosophy is interested exclusively in the universal, and it is monistic—its aim is to discover one principle from which everything can be derived. This tendency of philosophy, however, denatures human experience, which knows not one but three separate domains (which Kant had referred to in a different context), namely, God, the world, and humanity.

According to Rosenzweig, God (like the world and like humankind) is known through experience (the experience of revelation). In Greek religion, the most perfect manifestation of paganism, every one of these domains subsists by itself: the gods, the cosmos, and the human as the tragic, solitary, silent hero. Biblical religion is concerned with the relation between the three: the relation between God and the world, which is creation; the relation between God and human beings, which is revelation; and the relation between humans and the world, which leads to salvation. Under the influence of Schelling, whose term and concept he adopted, Rosenzweig pursued a “narrative philosophy” that renounces the ambition to find one principle for everything that exists and that follows biblical religion in focusing on the connections between the three domains and between the words and acts that bring about and develop these connections.

Biblical faith brought forth two valid religions—Christianity and Judaism. The first is described by Rosenzweig as the eternal way; the Christian peoples seek in the vicissitudes of time and history the way to salvation. In contrast to them, the existence of the stateless Jewish people is not concerned with time and history; it is—notwithstanding the hope for final salvation—already an eternal life, renewed again and again according to the rhythm of the Jewish liturgical year.

Martin Buber

Among the leading thinkers of the 20th century was Martin Buber (1878–1965), whose impact was felt by both Jews and non-Jews. In his early period, Buber was led, partly through empathy with Jewish and non-Jewish mysticism, to stress unitive experience and knowledge, in which the difference between one person and another and between the individual and God tend to disappear. But in his final period he taught—following, as he claimed, a suggestion of Ludwig Feuerbach (1804–72)—that a human being can realize himself only in a relation with another, who may be another person or God. This conception of the “I and Thou” relationship led to the formulation of Buber’s view of the dialogical life—the mutual, responsive relation between one person and another—and accounts for the importance that he attached to the category of “encounter.”

Emmanuel Lévinas

During the late 20th century the thought of the French Jewish philosopher Emmanuel Lévinas (1905–95) exercised worldwide influence. In his main work, Totality and Infinity (1961), Lévinas emphasized ethics, as opposed to epistemology, as the primary means for achieving one’s relation to the “Other.” This relationship is based on the existential and material need of the other person rather than on one’s abstract knowledge of him. In this philosophical program, Lévinas drew upon rabbinic tradition as well as the philosophical anthropology of Cohen, Rosenzweig, and Buber.