Lotze's first work was his dissertation "De futurae biologiae principibus philosophicis", with which he gained in July 1838 the degree of doctor of medicine. In 1840 he gained the degree of doctor of philosophy with his dissertation "De summis continuorum". He laid the foundation of his philosophical system in his "Metaphysik" (Leipzig, 1841) and his "Logik" (1843), short books published while still a junior lecturer at Leipzig University, whence he moved to Göttingen, succeeding Johann Friedrich Herbart in the chair of philosophy.