ABSTRACT
This chapter clarifies Leibniz's notion of substance in the Discourse with a view to explaining how that definition successfully distinguishes between substances and accidents. It discusses the merely nominal definition of substance with which Leibniz begins the passage and his theory of truth. It then explains why on Leibniz's theory of truth an accident is an entity with a concept so complete that it contains all its predicates. The chapter argues that appealing to Leibniz's Nominalism is no way of saving the definition of substance. It considers an important note Leibniz wrote at the margin of one of his letters to Arnauld and elucidates it on the basis of the argument. The chapter argues that the Discourse can then be seen as representing an evolution in Leibniz's thought on substance in the mid-1680s. Leibniz says that this Aristotelian explanation of substance is insufficient and merely nominal.
