300 WOLFF'S OPPONENTS. the Wolffian system by their manuals on different branches of philosophy. To this school belong also the following: Thiimmig {^Institutioiics Philosophies Wolfiame, 1725-26); the theologian Siegmund Baumgarten at Halle, the elder brother of the aesthete; the mathematician Martin Knutzen, Kant's teacher;* the literary historian Gottsched f at Leipsic : and G. Ploucquet, who in his Methodus Calculandi in Logicis, with a Conimcntatio de Arte Characteristica Uni- versali] appended to his Principia de Substantiis et PhcEnom- enis, 1753, took up again Leibnitz's cherished plan for a logical calculus and a universal symbolic language. The psychologist Kasimir von Creuz {Essay on the Soul, in two parts, 1753-54), and J. H. Lambert, :|: whom Kant deemed worthy of a detailed correspondence, take up a more independent position, both demanding that the Wolffian rationalism be supplemented by the empiricism of Locke, and the latter, moreover, in anticipation of the Critique of Reason, pointing very definitely to the distinction between content and form as the salient point in the theory of knowledge. Among the opponents of the Wolffian philosophy, all of whom favor eclecticism, A. Riidiger § and Chr. Aug. Crusius, I who was influenced by Riidiger, and, like him, a professor at Leipsic, are the most important. Riidiger divides philosophy according to its objects, " wisdom, justice, prudence," into three parts — the science of nature (which must avoid one-sided mechanical views, and employ ether, air, and spirit as principles of explanation); the science of duty (which, as metaphysics, treats of duties toward God, as natural law, of duties to our neighbor, and deduces both
- Benno Erdmann, M. Knutzen und seine Zeit, 1876.
f Th. W. Danzel, Gottsched tmd seine Zeit, 1848. X Lambert: Cosmological Letters, 1761 ; New Organon, 1764 ; Groundwork of Architectonics, 1 77 1. Bernouilli edited some of Lambert's papers and his cor- respondence. § Riidiger : Disputatio de eo quod Omnes Idece Oriantur a Sensione, 1704 ; Philospphia Synthetica, 1707 ; Physica Divina, 1716 ; Philosophia Pragmatica, 1723. I Crusius : De Usu et Limitibus Principii Rationis, 1743; Directions how to Live a Rational Life (theory of the will and of ethics), 1744 ; A Sketch of the Necessary Truths of Reason, 1 745 ; Way to the Certainty and Trustworthiness cf Human Knowledge, 1747. .
