The Harmony of Spinoza and Leibniz

According to a common reading, Spinoza and Leibniz stand on opposite ends of the modal spectrum. At one extreme lies ‘‘Spinoza the necessitarian,’’ for whom the actual world is the only possible world. At the other lies ‘‘Leibniz the anti-necessitarian,’’ for whom the actual world is but one possible world among an infinite array of other possible worlds; the actual world is privileged for existence only in virtue of a free decree of a benevolent God. In this paper, I challenge both of these readings. Spinoza is no necessitarian and Leibniz is no anti-necessitarian – at least as these characterizations are usually understood. Rather, I contend, Spinoza and Leibniz are both anti-essentialists; they believe that the modality of objects (both individually and as collected into a possible world) can vary relative to how those objects are conceived. This shared commitment to anti-essentialism allows them to consistently affirm both necessitarianism and its denial, relative to different ways of conceiving the world. Their embrace of this modal