FREGE,GOTTLOB AND EUCKEN,RUDOLD - COLLEAG UES IN THE DEVELOPMENTAL PHASE OF MODERN LOGIC

Frege and Eucken were colleagues in the faculty of philosophy at Jena University for more than 40 years. At times they had close scientific contacts. Eucken promoted Frege's career at the university. A comparis on of Eueken's writings between 1878 and 1880 with Frege's writings sh ows Eucken to have had an important philosophical influence on Frege's philosophical development between 1879 and 1885. In particular the cl assification of the Begriffsschrift in the tradition of Leibniz is inf luenced by Eucken. Eucken also influenced Frege's choice of philosophi cal and logical terms. Finally, there are analogous positions concerni ng relations between concepts and their expressions in natural languag e, Frege was probably also influenced by Eucken's use of the term 'ton e'. Eucken used Frege's arguments in his own fight against psychologis m and empiricism.