G. W. Leibniz

Gottfried Wilhelm Leibniz (1646–1716) was a German polymath whose work in metaphysics, logic, mathematics, and theology placed the question of God at the center of early modern philosophy. Trained at Leipzig and Altdorf, he served the Houses of Mainz and Hanover while corresponding with much of learned Europe. Independently of Newton, he developed the infinitesimal calculus; in philosophy he developed the doctrines of monads, pre-established harmony, and a substance metaphysics governed by the principle of sufficient reason and the principle of non-contradiction.

Leibniz's theistic arguments are distinctive: a contingency-based cosmological argument grounded in the PSR, a reformulated ontological argument (which he claimed Descartes's version required supplementing with a proof of God's possibility), and an argument from pre-established harmony among monads. In the Théodicée (1710), responding to Pierre Bayle, he argued that this world is the best of all possible worlds compatible with God's wisdom, goodness, and power, distinguishing metaphysical, physical, and moral evil. Voltaire famously satirized this doctrine in Candide, and Kant later criticized Leibniz's modal proofs in the Critique of Pure Reason. Bertrand Russell's 1900 study reopened debate about whether Leibniz's metaphysics derives from his logic. He remains a touchstone for contemporary discussions of contingency arguments, modal ontology, theodicy, and the rationality of theistic belief.