|Ehrenfried Walter von Tschirnhaus|
Ehrenfried Walter von Tschirnhaus (or Tschirnhausen), the German mathematician and physicist, was born in Kieslingswalde, near Görlitz, and became count of Kieslingswalde and Stolzenberg. He studied mathematics at Görlitz and at the University of Leiden, where the Cartesian philosophers Adriaan Heereboord and Arnold Geulincx were teaching.
After serving with the Dutch in 1672 during a war with France, Tschirnhaus studied further in Leiden and in Germany, and in 1674 he traveled to London, Paris, Rome, Sicily, and Malta. He met Benedict de Spinoza in Holland, English scientists in London, and he undoubtedly met Cartesian philosophers and scientists such as Jacques Rohault and Pierre-Sylvain Régis in Paris.
Tschirnhaus finally settled down in Kieslingswalde. He established several factories for manufacturing glass and for grinding magnifying glasses, and was associated with J. F. Böttger in the development of Meissen porcelain.
Tschirnhaus published various essays on mathematics and optics in the Acta Eruditorum from 1682 to 1698, and a philosophical treatise, Medicina Mentis, on methodology, logic, and theory of knowledge, which also explained some of his geometrical discoveries.
Medicina Mentis followed Tschirnhaus’s scientific interests; but some general features of the treatise were derived from Cartesianism, Spinoza, English empiricism, and, in some respects, from Gottfried Wilhelm Leibniz. Tschirnhaus’s “mental medicine” was intended as a method of discovering rational truth as a basis of a happy life. Only true knowledge can tame the passions, which are the source of error and therefore of unhappiness.
Knowledge comes only from the senses, but purely sensible knowledge—which Tschirnhaus called imagination—is passive, approximate, and relative, and must be governed by rigid precepts. Reason abstracts from imagination, producing universal and strict concepts.
The intellect considers things “as they exist in themselves”; that is, it penetrates their “real nature” and connects in one whole the real thing and its sensible and abstract representations. Reason operates by analysis, intellect by synthesis.
Only intellectual knowledge can reach truth and be communicated. Falsehood arises when intellect works like imagination. The criterion of truth is “what can be conceived”—that is, ideas insofar as they may be connected or not connected with one another.
This criterion does not rest simply on an abstract rule to be applied in each case, but on the possibility of connecting ideas in a comprehensive system. But for Tschirnhaus this system was not, as for the rationalists, a closed and independent cognitive order.
He considered the intellectual faculty to be the source of logical truth. But metaphysical truth comes from experience, and it is truth insofar as it has been deduced from experience by reasoning conforming to logical standards, and insofar as it is confirmed “through evident experiments.”
Intellectual knowledge operates by elaborating simple concepts, or “definitions”; by deducing simple properties, or “axioms,” from them; and by connecting the definitions in all possible ways to produce “theorems.” Tschirnhaus held that definition is real. It is a knowledge of causes that enables us to reproduce the object.
In its highest stages intellectual knowledge is knowledge of the natural world. Science is a whole, and should conform to the methodological ideal of mathematical clarity. Physics is the foundation of the other sciences. By demonstrating the rationality and necessity of all events, physics leads us to recognize divine providence. Human freedom arises from the command of God.
Although Tschirnhaus’s Medicina Mentis was quite famous in its own day and its methodology was an important source of Christian Wolff ’s ideas, it exerted no direct influence on the German Enlightenment.