CRUSIUS, CHRISTIAN AUGUST (1715-1775), German philosopher and theologian, was born on Jan. 1o, 1715, at Leuna, near Merseburg, in Saxony. He was educated at Leipzig, and be came professor of theology there in 175o, and principal of the university in 1773. He died on Oct. 18, 1775. Crusius opposed the philosophy of Wolff from the standpoint of religious orthodoxy. He attacked it mainly on the score of the moral evils that must flow from any system of determinism. The most important works of this period of his life are Entwurf der nothwendigen Vernunf t wahrheiten (1745), and Weg zur Gewissheit and Zuverliissigkeit der menschlichen Erkenntniss (1747). Though diffusely written, and neither brilliant nor profound, Crusius' philosophical books had a great but short-lived popularity.
There is a full notice of Crusius in Ersch and Gruber's Allgemeine Encyclo piidie. Consult also A. Marquardt, Kant and Crusius; and art. in Herzog-Hauck, Realencyklopadie.