Dogmatic Metaphysics and Tschirnhaus's Methodology

according to standard commentaries, Tschirnhaus’s main work, Medicina mentis (1687; 2nd ed. 1695),¹ supposedly furnished the methodological basis for the Leibnizian-Wolffian metaphysics.² Christian Wolff and his disciples, at any rate, preferred to think so. Wolff taught classes on Tschirnhaus and claimed that he had developed his own tenets on the basis of Tschirnhaus’s ideas; Johann Christoph Gottsched praised the Medicina mentis as the basic methodology of the Wolffian enlightenment.³ Mirroring these views, W. Wundt and H. J. de Vleeschauwer saw in Tschirnhaus the inventor of the “geometric method” adopted by the School Philosophers.⁴ According to M. Paolinelli, Wolff’s conception of the mathematical method is “totalmente dipendente da Tschirnhaus.”⁵ For L. W. Beck, the Medicina mentis is an example of an “extreme epistemological rationalism,” and because of this, Tschirnhaus, Wolff, and the Wolff-critic Christian August Crusius allegedly formed the front later attacked by Kant.⁶

I argue that these assessments are mistaken. Ehrenfried Walther von Tschirnhaus (1651–1701) was not the methodological father of the Wolffian system—at least, he did not want to be. Tschirnhaus’s view of the geometric method differed from the conception of Wolff and his disciples; in contrast to these dogmatic metaphysicians, Tschirnhaus also argued for a quantitative approach to natural phenomena. Tschirnhaus did not advocate an extreme epistemological rationalism, but rather a motley mixture of empirical and rational elements. His methodology was geared to the fact that he was primarily an experimental researcher interested in the practical strategies of experimentation and empirical investigation. Finally, Tschirnhaus, Wolff, and Crusius did not form the front attacked by Kant—Kant took issue with Wolff and Crusius but not with Tschirnhaus.⁷

An examination of Tschirnhaus raises many interesting questions. What was his philosophical relationship to Spinoza, his close friend and correspondent? To what extent, if at all, was he influenced by Leibniz? What was Tschirnhaus’s involvement in the Western invention of porcelain? I do not wish to pursue any of these questions here; they would require inquiries of their own.⁸ In this essay, I wish to investigate what Tschirnhaus’s main philosophical work was about and how Tschirnhaus’s methodological proposals relate to the dogmatic metaphysics of the Leibnizian-Wolffian School Philosophy. I shall examine the basic thrust of the Medicina Mentis, compare Tschirnhaus’s proposed methodology to the methodology of the dogmatic metaphysicians who claimed to follow Tschirnhaus, and hope to shed some light on the functions of mathematics and experimentation, which are crucial for appraising Tschirnhaus’s methodology as a whole. My central claim is that Tschirnhaus’s ideas are more level-headed and more differentiated than one might expect, and that his apparent affinity to a bankrupt metaphysics rests on an illusion.

1. the purpose and focus of philosophy

With the Medicina mentis, Tschirnhaus hoped to devise a set of strategies that would transform philosophy into a successful enterprise and that would allow the reliable production of knowledge. Tschirnhaus believed that scholastic, aprioristic metaphysics needed to be overcome; a scholar dealing only with empty notions, who wastes his time with subtleties instead of doing hands-on research, and whose knowledge is about speculative words instead of real objects, is a verbalis philosophus. Such a windbag does not deserve to be called a philosopher (M xiif., 29; H 39, 69).⁹ Instead, the personified paragon of exemplary philosophy is the realis philosophus (M xii; H 39): a researcher investigating real things.

What are the “real things” philosophy should investigate? Tschirnhaus distinguishes real, sensory, and rational things as the three possible types of entities and defines real things as physical objects (entia physica; M 78, cf. also 84; H 107, 112). Real things or entia physica are bodies (corpora) that are made of matter and that are in motion or at rest (M 84, 89; H 112, 116). Sensory things or res imaginibiles are the objects we can imagine and perceive.¹⁰ Rational things or res rationales are the objects of mathematics, such as curves and straight lines (M 82–4, 89; H 110–11, 115). Accordingly, philosophy, as the...