WOLFF (less correctly Wolf), CHRISTIAN (1679—1754), German philosopher and mathematician, the son of a tanner, was born at Breslau on the 24th of January 1679. At the university of Jena he studied first mathematics and physics, to which he soon added philosophy. In 1703 he qualified as Privaldozent in the university of Leipzig, where he lectured till 1706, when he was called as professor of mathematics and natural philosophy to Halle. Before this time he had made the acquaintance of Leibnitz, of whose philosophy his own system is a modification. In Halle Wolff limited himself at first to mathematics, but on the departure of a colleague he added physics, and presently included all the main philosophical disciplines. But the claims which Wolff advanced on behalf of the philosophic reason (see Rationalism) appeared impious to his theological colleagues. Halle was the headquarters of Pietism, which, after a long struggle against Lutheran dogmatism, had itself assumed the characteristics of a new orthodoxy. Wolff's professed ideal was to base theological truths on evidence of mathematical certitude, and strife with the Pietists broke out openly in 1721, when Wolff, on the occasion of laying down the office of pro-rector, delivered an oration "On the Practical Philosophy of the Chinese" (Eng. tr. 1750), in which he praised the purity of the moral precepts of Confucius, pointing to them as an evidence of the power of human reason to attain by its own efforts to moral truth. For ten years Wolff was subjected to attack, until in a fit of exasperation he appealed to the court for protection. His enemies, however, gained the ear of the king Frederick William I. and represented to him that, if Wolff's determinism were recognized, no soldier who deserted could be punished, since he would only have acted as it was necessarily predetermined that he should. This so enraged the king that he at once deprived Wolff of his office, and commanded him to leave Prussian territory within forty-eight hours on pain of a halter. The same day Wolff passed into Saxony, and presently proceeded to Marburg, to which university he had received a call before this crisis. The land grave of Hesse received him with every mark of distinction, and the circumstances of his expulsion drew universal attention to his philosophy. It was everywhere discussed, and over two hundred books and pamphlets appeared for or against it before 1737, not reckoning the systematic treatises of Wolff and his followers. In 1740 Frederick William, who had already made overtures to Wolff to return, died suddenly, and one of the first acts of his successor, Frederick the Great, was to recall him to Halle. His entry into the town on the 6th of December 1740 partook of the nature of a triumphal procession. In 1743 he became chancellor of the university, and in 1745 he received the title of Freiherr from the elector of Bavaria. But his matter was no longer fresh, he had outlived his power of attracting students, and his class-rooms remained empty. He died on the 9th of April 1754.
The Wolffian philosophy held almost undisputed sway in Germany till it was displaced by the Kantian revolution. It is essentially a common-sense adaptation or watering-down of the Leibnitzian system; or, as we can hardly speak of a system in connexion with Leibnitz, Wolff may be said to have methodized and reduced to dogmatic form the thoughts of his great predecessor, which often, however, lose the greater part of their suggestiveness in the process. Since his philosophy disappeared before the influx of new ideas and the appearance of more speculative minds, it has been customary to dwell almost exclusively on its defects—the want of depth or freshness of insight, and the aridity of its neo-scholastic formalism, which tends to relapse into verbose platitudes. But this is to do injustice to Wolff's real merits. These are mainly his comprehensive view of philosophy, as embracing in its survey the whole field of human knowledge, his insistence everywhere on clear and methodic exposition, and his confidence in the power of reason to reduce all subjects to this form. To these must be added that he was practically the first to "teach philosophy to speak German." The Wolffian system retains the determinism and optimism of Leibnitz, but the monadology recedes into the background, the monads falling asunder into souls-or conscious beings on the one hand and mere atoms on the other. The doctrine of the pre-established harmony also loses its metaphysical significance, and the principle of sufficient reason introduced by Leibnitz is once more discarded in favour of the principle of contradiction which Wolff seeks to make the fundamental principle of philosophy. Philosophy is defined by him as the science of the possible, and divided, according to the two faculties of the human individual, into a theoretical and a practical part. Logic, sometimes called philosophic rational is, forms Ihe introduction or propaedeutic to both. Theoretical philosophy has for its fjarts ontology or philosophic prima, cosmology, rational psychology and natural theology; ontology treats of the existent in general, psychology of the soul as a simple non-e.xtcnded substance, cosmology of the world as a whole, and rational theology of the existence and attributes of God. These are best known to philosophical students by Kant's treatment of them in the Critique oj Pure Reason. Practical philosophy is subdivided into ethics, economics and politics. Wolff's moral principle is the realization of human perfection.
Wolff's most important works are as follows: Anfangsgründe aller mathematischen Wissenschaften (1710; in Lalin, Elementa malheseos universae, 1713—1715); Verniinjlige Gedanken von den Krajlen des menschhchen Verslandes (1712; Eng. trans. 1770); Vern. Ged. von Colt, der Welt und der Secle des Menschen (1719); Vern. Ced. von der Menschen Thun und Lassen (1720); Vern. Ged. von dem gesellschafthchen Liben der Menschen (1721); Vern. Ced. von den Wirkungen der Natur (1723); Vern. Ged. von den Absichlen der natiirlichen Dinge (1724); Vern. Ced. von dem Cebraur.he der Thcile in Menschen, Thicren und Pflanzen (1725); the last seven may briefly be described as treatises on logic, metaphysics, moral philosophy, political philosophy, theoretical physics, teleology, physiology: Philosphia rationalis, sive logica (1728); Philosophia prima, sive Ontologia (1729); Cosmologia generalis (1731); Psychologia empirica (1732); Psychologia rationalis (1734); Theologia naturalis (1736-1737); Philosophia practica universalis (1738-1739); Jus naturae and jus Gentium (1740-1749); Philosophia moralis (1750-1753). His Kleine philosopinsche Schrijten have been collected and edited by G. F . Hagen (1736-1740). In addition to Wolff's autobiography (Eigene Lebensbcschrcibung, ed. H. Wuttke, 1841) and the usual histories of philosophy, see W. Schrader in Allgemeine deutsche Biographie, xliv.; C. G. Ludovici, Ausfiihrlicher Enlwurf einer voilstdndigen Historic der Wolff'schen Philosophie (1736-1738); J. Deschamps, Cours abrege dc la philosophies woljfienne (1743); F. W. Kluge, Christian von Wolff der Philosoph (1831); W. Arnsperger, Christian Wolffs Verhaltnis zu Leibniz (1897).