For what are things independent of reason? To answer that would be like to judge without judging, or to wash the fur without getting it wet.
—Gottlieb Frege
Over the course of the preceding pages, I have attempted to develop an interpretation of Spinoza’s metaphysics according to which he should be counted among the metaphysical realists. His basic ontological categories—substance, attribute, and mode—are not, although they are correlated with them, reducible to nor grounded in anything epistemic, psychological, or conceptual. Neither are the basic metaphysical relations that structure his world—inherence and causation—reducible to nor grounded in anything epistemic, psychological, or conceptual. Rather, Spinoza is a realist and a rationalist. He believes that the metaphysical and the epistemic/conceptual mirror one another in such a way that the structure of the world is accessible to philosophical reason, but he does not try to justify this assumption by reducing the metaphysical to the epistemic/conceptual. He merely presumes it to be true and proceeds to philosophize on this basis. If it is to find justification at all, it will only be because if it weren’t true, then philosophy as he conceives it would be impossible. Thus, to the extent that Spinoza’s philosophy helps us solve philosophical problems and otherwise understand the world, the hypothesis that being and reason mirror one another is vindicated....