Abstract

Jakob Friedrich Fries is one of the most important representatives of the Critical Philosophy, someone who built immediately on the original Kantian philosophy. -/- Fries was born in 1773 in Barby (on the Elbe). In 1805 he was extraordinary professor for philosophy in Jena and in the same year was ordinary professor for philosophy in Heidelberg. Returning to Jena in 1816, one year later he was compulsorily retired because of his participation at the nationalistic and republican Wartburg Festival. In 1924 he obtained a professorship for physics and mathematics, and in 1838 he was given back a professorship for philosophy. He died in 1843 in Jena. -/- The book summarizes the research results of the DFG-Project "Jakob Friedrich Fries' Influence on the Sciences of the 19th Century". The research project was carried out by Dr. Kay Herrmann (Institute of Philosophy, Jena University) and Prof. Dr. Wolfram Hogrebe (Institute of Philosophy, Bonn University). Such a study has special importance. There is available a large amount of literature about the "speculative contemporaries" of Fries, like Fichte, Schelling, and Hegel. In contrast to the "speculative philosophy", there has been published only a few studies about the Friesian natural philosophy. Fries was, in his natural-philosophical studies, looking for a link between philosophy and modern sciences, wheras his "speculative philosophical" contemporaries felt obligated to stick primarily to a descriptive, phenomenal view of nature. So far the question "How was mathematical natural philosophy regarded by scientists and mathematicians of the 19th century?" has hardly been investigated. Archival studies showed that this gap in Fries-research can be filled. The Friesian correspondence turned out to be a rich gold mine. -/- The present publication is more than a research report. The monographic first part is intended to introduce the foundations of the Friesian theory of cognition, the Friesian methodology, and the Friesian natural philosophy. This should facilitate entry into Friesian philosophy. -/- The Friesian theory is analyzed from two points of view: •How did Fries suceed in continuing and improving the Kantian approach? Is Fries able to remove the weak points of Kantian philosophy? -/- •What is the current significance of the Friesian approach? There are some interesting similarities between the Friesian approach and modern philosophical theories (such like Chomsky's theory of "universal grammer"). The lasting core of the Friesian theory of cognition is: To use empirical studies for working on philosophical problems. -/- Chapters 3 and 4 are scientific-historically oriented. These chapters analyze the Friesian position in scientific and mathematical debates (debates about the a priori foundations of physics, the problem of the identification of physics as an independent discipline, the problem of the boundary between chemistry and physics, the problem of mathematization of the sciences, the theory of the imponderabilia, the systematics and structure of sciences and mathematics, problems of infinity, the differential calculus, the theory of parallel lines) and the relation between Fries and the scientists of the 19th century. The book contains the latest findings gained by evaluation of the Friesian unpublished work (for example the correspondence with W. Weber, C. F. Gauß, E. F. Apelt, O. Schlömilch, Ch. Reichel, B. A. v. Lindenau, L. Gmelin, E. G. Fischer, A. N. Scherer, J. S. C. Schweigger) -/- One result of the research project is that some important scientists took a favourable view of the Friesian theory, but the influence of the Friesian philosophy on the sciences of the 19th century was very limited. The causes are very complex: An anti-natural-philosophical spirit of age, the limits of the Kantian inspired philosophy and some unfavourable aspects in the biography of Fries. -/- For the first time the voluminous Fries-Reichel-correspondence was evaluated. The Fries-Reichel-correspondence contains the Friesian approach to prove the 11th Euclidean axiom, and the whole transcript of the Friesian attempt at proof is given. // Der erste Teil des Buches will in die Grundprobleme Fries’scher Erkenntnis­theorie, Methodenlehre und Naturphilosophie einführen, wobei das Hauptaugenmerk auf die Fortführung der kantischen Ansätze durch Fries sowie auf die aktuelle Interpretation der Fries’schen Lehre gerichtet ist. Der wissenschaftshistorisch ausgerichtete zweite Teil analysiert Fries’ Stellung zu naturwissenschaftlichen und mathematischen Diskussionsrichtungen (Probleme der Identifizierung der Physik als eigenständige Disziplin, der Grenzziehung zwischen Physik und Chemie, der Mathematisierung der Naturwissenschaften, der Imponderabilientheorie, der Systematik von Naturwissenschaft und Mathematik, des Unendlichen, der Parallelentheorie usw.) sowie sein Verhältnis zu Naturwissenschaftlern und Mathematikern seiner Zeit. Das Buch enthält neue Erkenntnisse, die aus der Auswertung zahlreicher Nachlassmaterialien gewonnen wurden. Erstmalig wird unter dem Blickwinkel „Fries als Naturwissenschaftler und Mathematiker“ auch der sehr umfangreiche Reichel-Briefwechsel ausgewertet. Dem Reichel-Briefwechsel entstammt auch Fries’ Versuch eines Beweises des Parallelenaxioms, der in diesem Buch erstmalig in transkribierter Form vollständig vorliegt. -/- .