Gottfried Wilhelm Leibniz

Leibniz was a universal genius — diplomat, librarian, mining engineer, mathematician, philosopher, and the (co-)inventor of the calculus alongside Newton. Their bitter priority dispute poisoned English-German mathematical relations for a century.

His philosophy is dazzling and strange. The world, he argued, is composed of an infinity of monads: simple, indivisible, immaterial substances, each of which contains within itself the entire history of the universe from its own perspective. Monads do not interact; instead, God arranged from the start a pre-established harmony so that everything appears to causally affect everything else. Out of all the logically possible worlds, God chose to create this one because it has the optimal balance of richness and order — hence the best of all possible worlds.

Voltaire savaged this last idea in Candide after the 1755 Lisbon earthquake. The cosmic optimism became the punchline. But the deeper Leibniz — the analyst of possibility, sufficient reason, and the principle of contradiction — remains one of the most original logicians in history.