Biography
Where Leibniz already appears in this vault
His central idea is load-bearing in two places:
- Contingency Argument — the apologetic argument is built on his Principle of Sufficient Reason: for everything that exists there must be a sufficient reason why it exists rather than not. See its Step 3 and the “Leibniz’s Version” section.
- Candide - Voltaire — the most famous attack on what he built on that principle. Voltaire targets the conclusion that this is therefore “the best of all possible worlds,” using the 1755 Lisbon earthquake as the case that no sufficient reason redeems. The phrases “sufficient reason” and “cause and effect” appear in the novel as punchlines aimed at him.
Worth noting the asymmetry: Voltaire attacks the optimism, not the principle. You can hold PSR without holding that the resulting world is the best available — which is why the Contingency Argument survives Candide even though Pangloss does not.
Israel — Leibniz’s answer to the radical challenge
Source-specific connections from Jonathan I. Israel’s Radical Enlightenment:
- Engagement preceded opposition: Leibniz pursued Spinoza’s texts, circle, and direct conversation, recognized important affinities, and later acknowledged briefly inclining toward the Spinozists. Israel distinguishes this serious encounter from lasting acceptance of their entire system. Chapter 26 · Printed pp. 502–506 (file not included in this release)
- A rational defense rather than submission alone: Against Steno’s fideism, Leibniz insisted that demonstrated truths constrain religious belief. His defense of providence also informed a model of princely government justified through reason, virtue, and common welfare. Printed pp. 507–510 (file not included in this release)
- The reconciliation remains disputed: Multiple substances and differentiated necessity were meant to combine mechanical explanation with wise divine choice. Clarke challenged whether a perfect God choosing the best truly escapes necessity. Israel presents this as an unresolved test of the system, not a settled proof of its success. Printed pp. 511–514 (file not included in this release) · Chapter 25: why a new moderate foundation mattered