Abstract

In Ep. 50, Spinoza argues at length that “someone who calls God one or unique does not have a true idea of God, or is speaking improperly about him.” This text is striking, given the declarations in many writings, including the Ethics, that God is the one, unique substance. While recent commentators have attempted to render Ep. 50 consistent with the rest of Spinoza’s corpus, I instead argue that Spinoza’s stance on God’s oneness evolved over the course of his career. This evolution, which in fact contains a number of twists and turns, is driven not only by consideration of the proper meaning of ‘one’ and ‘unique’ but also by the question of whether God’s essence and God’s existence are numerically identical. Regarding the latter, I argue that Spinoza came to reject this identity claim late in life, and that this explains his final change in viewpoint regarding God’s oneness in Ep. 83.