Stephen Puryear

I propose a straightforward reconciliation of Leibniz’s conception of bodies as aggregates of simple substances (i.e., monads) with his doctrine that bodies are the phenomena of perceivers, without in the process saddling him with any equivocations. The reconciliation relies on the familiar idea that in Leibniz’s idiolect, an aggregate of Fs is that which immediately presupposes those Fs, or in other words, has those Fs as immediate requisites. But I take this idea in a new direction. Taking notice of the fact that Leibniz speaks of three respects in which one thing may immediately presuppose others--i.e., with respect to its being, its existence, and its reality--I argue that a phenomenon having its being in one perceiving substance (monad) can plausibly be understood to presuppose other perceiving substances (monads) in two of these respects. Accordingly, good sense can be made of both the claim that a phenomenon in one monad is an aggregate of other monads (in Leibniz’s technical sense of 'aggregate') and the (equivalent) claim that the latter monads are constituents of the phenomenon (in his technical sense of 'constituent'). So understood, the two conceptions of body are perfectly compatible, just as Leibniz seems to think.

Leibniz has almost universally been represented as denying that created substances, including human minds and the souls of animals, can causally interact either with one another or with bodies. Yet he frequently claims that such substances are capable of interacting in the special sense of what he calls 'ideal' interaction. In order to reconcile these claims with their favored interpretation, proponents of the traditional reading often suppose that ideal action is not in fact a genuine form of causation but instead a merely apparent influence which serves to 'save the appearances.' I argue that this traditional reading distorts Leibniz's thought and that he actually considers ideal action a genuine (though non-standard) form of causation.