The Influence of Leibniz on Brentano’s Theodicy

Franz Brentano (1838–1917) admired G.W. Leibniz (1646–1716) as representing the ascending phase in the development of philosophy during the modern period. Along with Aristotle and Thomas Aquinas, Leibniz exercised a significant influence on Brentano’s treatment of several topics in metaphysics and epistemology as well as in natural theology. In this paper, I focus primarily on those topics that bear directly on Leibniz’s influence in Brentano’s theodicy: first by exploring in detail the similarities between Leibniz’s theodicy and Brentano’s; second, by taking special note of Brentano’s so-called psychological proof of God’s existence; third, by elaborating in a provisional way, the potentially phenomenological aspects of Leibniz’s and Brentano’s theodicies, their advantages, and their shortcomings. In the end, I suggest that the theodicies of both Leibniz and Brentano offer primarily ontological optimism, but that a truly moral optimism, though it can be developed further in ways suggested by phenomenology, remains philosophically out of reach.