WOLFF (Wolfius), CHRISTIAN. - Philosopher, b. at Breslau on 24 Jan. 1679, d. at Halle on 9 Apr. 1754.
Presented by Leibniz to the University of Halle in 1706 as a mathematical philosopher (*Anfangsgründe sämtlicher mathematischer Wissenschaften*, Halle 1710), he encountered, on account of his rationalism, the opposition of the Pietists, led by Francke, who procured his exile from Prussia under Frederick William I (1723). Taking refuge at the University of Marburg, he returned to Halle with the accession of Frederick II (1740) and became the dominant figure of the Enlightenment philosophy in Germany.
His early works (Halle and Frankfurt 1712–23), in German, under the general title *Vernünftige Gedanken* (“Rational Thoughts”), are devoted to the principal themes of Leibnizian philosophy (*Dell’intelletto umano*, 1712; *Di Dio, del mondo e dell’anima umana*, 1719; *Delle azioni degli uomini in ordine alla loro felicità*, 1720; *Della vita sociale degli uomini*, 1721; *Delle attività della natura*, 1723; *Dei fini delle cose naturali*, 1723; *Delle parti dell’uomo, degli animali e delle piante*, 1723), and emphasize within it the methodological connections with Cartesian subjectivism, the appeal to clear and distinct ideas, and the benefits of the universal dissemination and application of philosophy.
His mature Latin works (Frankfurt and Leipzig 1728–53) form a vast exposition of the entire system of intellectualist philosophy, with an emphasis on Aristotelian-Scholastic motifs and the objective values of metaphysics and science. In this second, so-called Leibniz-Wolffian system, the theory of the incommunicability of monads is entirely abandoned, this having been attributed to the persecution suffered by the author. The system, which remained in use until the ascendancy of Hegel’s Encyclopaedia (v.), comprises: *Philosophia rationalis, sive Logica* (1728); *Philosophia prima seu Ontologia* (1730); *Cosmologia generalis* (1731); *Psychologia empirica* (1731); *Psychologia rationalis* (1734); *Theologia naturalis* (1736–37); *Philosophia practica universalis* (1738–39); *Ius naturae* (1740–48); *Ius gentium* (1750); *Philosophia moralis seu Ethica* (1750–53); *Oeconomica* (1750). Wolff also published a collection of minor writings (*Gesammelte kleinere Schriften*, 6 vols., Halle 1736–40). An autobiography (*Eigene Lebensbeschreibung*) was edited by Wuttke (Leipzig 1841).
The fundamental principle of his logic is, for Wolff, the principle of non-contradiction (A is not non-A); this alone gives immediate certainty of being, which is truth; and to it is opposed the contradictory and uncertain character of the empirical world. In its positive sense, this principle is transformed into that of coherence or connection (identity, excluded middle), from which is deduced the principle of sufficient reason. All forms of knowledge and science thus present themselves in two modes: one purely rational, attained through the non-contradictoriness of reasoning and a priori; the other empirical, or descriptive of the relations between ideas and phenomena. The former includes analysis and deduction, the latter induction and the experimental method. There thus arises a higher or intellectual, scientific and philosophical knowledge, and a lower or sensible, historical knowledge, in every aspect of learning. Philosophy is the science of the possible, deduced from reason; to attain from these the truths of fact requires a *complementum possibilitatis*. Wolff’s Encyclopaedia thus imposed a science constituted according to the model of Cartesian analysis, but supported by the systematic description of phenomena according to experience.
Its cornerstone is ontology, as the doctrine of ideal and real being. Ideal being is pure *ens rationis*, logically constructed through analytic proofs: from this, in a new form, through Wolff and his followers, the classical metaphysics of God, the cosmos and the soul was deduced. Its postulate is that the idea of being, transparent as possible in the non-contradictoriness of thought, is itself absolute being, God, and the foundation of the existence of created things, in which possibility and reality coincide. As is well known, Kant and Hegel (v.) accepted this postulate, but criticized the justification it provided for the three metaphysical dogmas.
Wolffian ontology also contains the theory of particular, created or worldly substances, of which it claims to know what they intrinsically are through scientific knowledge of their inherent or independent activities, so as to eliminate the derivation from the divine substance presumed by Spinoza. Wolff’s substances are not incommunicable monads, for they also have relations with one another, but “atoms of nature”: they are in themselves unextended, yet each occupies a physical point from which it exercises its mechanical and motive forces, and weaves these into relations with adjacent substances; this reciprocal relation forms space, in which bodies appear as groups of substance, and phenomena. Pre-established harmony thus acquires a physical meaning, akin to the *ordo idearum et rerum* of Cartesian rationalists and their systems of cosmic clockwork: the world of nature is a rigorously ordered and connected system according to rational laws, from which Wolff excludes chance and contingency as belonging solely to divine creation. He also posits a pre-established harmony between soul and body, but admits physical influence between the two conjoined substances. In this way, in defining the substance of the soul, he is led to attribute necessary importance to its intrinsic faculties or powers, abstractly defined. Nevertheless, his distinction between empirical psychology (introspective, descriptive) and rational psychology (substantial), though at the time lacking in experimental content, created in the former a new science.
Wolff’s doctrine of law and morality, rigorously founded on the rationality of duty and of perfection productive of happiness, suffers from Enlightenment abstractions (widely criticized by Kant [V. in *Critique of Practical Reason*]), but through its systematic order and the completeness of its exposition it found many followers among disciples and contemporaries (Bilfinger, Meier, Baumeister). By contrast, the popularization of Wolffian theoretical philosophy (Thümming, Knutzen, Formey) BAUMGARTEN, MICHAEL (v.) met with numerous opponents (Rüdiger, Crusius, Darjes, Merian, Ploucquet), supported by the Berlin Academy.