Moses Mendelssohn (1729-1786) was the most important philosopher of the Jewish Enlightenment (Haskalah) and the figure who most decisively mediated between the Jewish biblical tradition and the European Enlightenment. A self-educated son of a Torah scribe from Dessau who rose to become one of the most admired philosophers in German-speaking Europe - intimate with Lessing, respected by Kant, celebrated in the salons of Berlin - Mendelssohn embodied in his person the thesis he argued in his philosophy: that the Jewish tradition is not an obstacle to rational Enlightenment but one of its deepest sources. His Jerusalem, or on Religious Power and Judaism (1783) is the founding text of modern Jewish political philosophy, arguing for the separation of church and state on grounds derived from the nature of religion itself, and for the distinctive character of Judaism as a religion of revealed law rather than revealed doctrine.
The Thinker and His Work
Mendelssohn arrived in Berlin at age fourteen, almost penniless, following his teacher Rabbi David Fraenkel who had moved to serve the Berlin Jewish community. He educated himself in German, Latin, French, mathematics, and philosophy - reading Leibniz, Wolff, and Locke - while supporting himself as a bookkeeper in a silk merchant's firm. His Philosophical Dialogues (1755), written in elegant German, brought him to the attention of the literary world, and his friendship with the dramatist Gotthold Ephraim Lessing - who modeled the noble Nathan in Nathan the Wise on Mendelssohn - established him as a central figure in German intellectual life.
Jerusalem was prompted by a challenge from the theologian Johann Caspar Lavater, who had publicly asked Mendelssohn to either refute the arguments for Christianity that Lavater had presented to him or convert. Mendelssohn refused conversion but was forced to articulate publicly his understanding of Judaism's relationship to reason, revelation, and political life.
Biblical Texts Engaged
Deuteronomy 6:4 - 'Hear, O Israel: The Lord our God, the Lord is one' - the Shema, the central declaration of Jewish faith - grounds Mendelssohn's account of Judaism's rational core. The Shema's affirmation of divine unity is, for Mendelssohn, not a claim that requires supernatural revelation to be credible but a truth that reason itself can reach. Universal rational truths - the existence and unity of God, divine providence, the immortality of the soul - are available to all human beings through reason; they do not require the specific revelation of the Torah to be known.
Leviticus 19:18 - 'you shall love your neighbor as yourself' - is the moral core of the Torah that Mendelssohn regards as continuous with universal natural law. The Torah's ethical commands are not arbitrary divine legislation but the specification, for the particular community of Israel, of universal moral truths.
Romans 2:14 - 'For when Gentiles, who do not have the law, by nature do what the law requires, they are a law to themselves' - appears in Mendelssohn's argument (paradoxically, citing Paul) that natural moral law is accessible to all human beings, Jew and Gentile alike. This natural moral law is the foundation; the specific Mosaic law is its particularization for Israel.
Core Argument
Jerusalem's argument has two parts. The first argues for the separation of church and state on grounds internal to the nature of religion. Religion concerns the inner conviction of the soul, which can only be produced by persuasion and never by coercion. The state, which has legitimate use of force, therefore has no business in matters of religious conviction. This argument runs parallel to Locke's Letter Concerning Toleration but derives it differently: Mendelssohn grounds religious toleration not in natural rights (though he appeals to these) but in the nature of genuine religious conviction as necessarily free.
The second part argues for the distinctive character of Judaism. Unlike Christianity, Mendelssohn argues, Judaism does not require its adherents to assent to revealed doctrines as conditions of salvation. The Torah gives Israel a revealed law - a specific way of living, organized around the commandments - not a revealed creed. Judaism's revealed component is practical (how to live) not theoretical (what to believe). Since universal rational truths are available to reason, and since Judaism's revelation is of law rather than doctrine, there is no conflict between being a rational Enlightenment philosopher and an observant Jew.
Intellectual Context
Mendelssohn was working within the German rationalist tradition of Leibniz and Christian Wolff, who had argued that reason and revelation were compatible because both came from the same rational God. He was also responding to the challenge that Enlightenment rationalism posed to Jewish particularity: if all rational people can reach the same truths by reason, what is the point of the Torah's specific legislation? His answer - that the Torah's law preserves the Jewish community's distinctive way of life and thereby maintains the living tradition of rational monotheism in the world - was a sophisticated response, though later critics (from within and outside Judaism) found it inadequate.
Reception and Critique
Kant respected Mendelssohn deeply but found his metaphysics (particularly his defense of rational psychology and the immortality of the soul) insufficiently critical - his Critique of Pure Reason's 'paralogisms' chapter can be read as a partial critique of Mendelssohn's position. Kant's distinction between autonomy and heteronomy - between moral law self-legislated by reason and moral law received from an external authority - made the revealed law of Torah seem, on Kantian grounds, a form of heteronomy incompatible with genuine moral autonomy.
Hegel's critique was sharper: in Early Theological Writings he argued that the Judaism of commandment was the model of unhappy consciousness - the self experiencing its own most fundamental law as external and alien rather than self-given. This anti-Jewish distortion had enormous influence on subsequent Protestant theology's understanding of 'law versus grace.'
Within Jewish thought, the Reform movement drew on Mendelssohn's emphasis on rational ethics as the core of Judaism to argue for the abrogation of the ceremonial law; Mendelssohn himself had resisted this conclusion, arguing that the ceremonial law remained binding for Jews. The Orthodox response insisted that Mendelssohn's rationalism was incompatible with full commitment to Torah as divine revelation.
Legacy
Mendelssohn's translation of the Torah into German (using Hebrew script, printed with a Hebrew commentary, the Biur) was one of the most culturally significant acts of the Haskalah: it brought German literary culture to Jews who could not read German script, and Jewish biblical scholarship to German readers. It was both an act of cultural integration and an act of religious translation - making the Hebrew Bible legible to modernity.
His Jerusalem established the framework for modern Jewish political philosophy: the claim that Jews can be full citizens of modern liberal states while remaining fully Jewish, because Judaism's distinctiveness lies in its law and community rather than in doctrinal claims that conflict with universal reason. This framework was developed by Hermann Cohen, Franz Rosenzweig, and ultimately by contemporary Jewish political philosophers such as Michael Walzer and David Novak.
Key Passages
'Judaism boasts of no exclusive revelation of eternal truths that are indispensable to salvation, of no revealed religion in the sense in which that term is usually understood. Revealed legislation, laws, commandments, ordinances - these were revealed to them by Moses in a miraculous and supernatural manner; but no doctrinal opinions, no saving truths, no universal propositions of reason.' (Jerusalem, Part II, trans. Arkush)
Contemporary Relevance
Mendelssohn's argument that religious communities can be full participants in liberal democratic societies while maintaining their distinctive traditions and practices - that pluralism does not require the reduction of all traditions to a common secular denominator - is one of the most important contributions of the Jewish Enlightenment to contemporary political philosophy. His insistence that the Hebrew Bible contains universal rational truths that are the common property of humanity, not the exclusive possession of any one community, anticipates the contemporary project of interfaith dialogue and comparative ethics. The question he raised - how a particular tradition can be both genuinely particular and genuinely universal - remains the central question for every religious community navigating the demands of pluralistic modernity.