Abstract

This article discusses the final development of Gottfried Wilhelm Leibniz’s metaphysics: the theory of monads. It examines Leibniz’s arguments for monads as mindlike “simple substances,” his description of the properties of monads, and the distinction he draws among different types of monads. The remainder of the article focuses on two problems that attend Leibniz’s claim that reality ultimately consists solely of monads and their internal states (perceptions and appetitions). The first problem is whether a relation among monads can account for the supposed unity of a living body or corporeal substance; the second is whether the metaphysics of monads supports a plausible explanation of the reality of matter. With regard to the second problem, the article explores Leibniz’s thesis that monads are, in two senses, “requisites” of matter. It concludes with reflections on the limits of his attempt to explain the physical world in terms of monads alone.