Leibniz and Materia Prima: Force and Monadic Perception

In his middle period, Leibniz proposed a radical reinterpretation of scholastic materia prima. In the 1680s and early 1690s, Leibniz set out a world whose basic constituents were corporeal substances. These corporeal substances were conceived of as genuine unities on the model of a human being: a soul or form, united with a body or matter. These constituents of the corporeal substance were also interpreted in terms of active and passive force. In this way, the primary matter of a substance was identified with impenetrability and resistance. Primary matter so understood was not itself extended, but it was that from which extension arises. However, in the mid-1690s, Leibniz’s ontology changed: instead of a world of corporeal substances, Leibniz sought to make a world in which monads, simple substances were at the metaphysical ground level. In this talk, I would like to explore what becomes of materia prima in this new monadological metaphysics. Leibniz often (though not always) wanted to keep both monads and corporeal substances. But where, then, should one put the materia prima? Invariably he held that monads had primary matter. But, then, how should one understand the relation between the materia prima at the monadic level, and extension and resistance at the level of bodies? If there is matter at the monadic level, is matter also found at the level of bodies? Furthermore, how can one understand the notion of materia prima as it applies to non-extended monads? I will argue that Leibniz didn’t have a single answer to this question, but that in his later writings, he is struggling with a way to accommodate his understanding of materia prima to his new metaphysics.