Identity of Part, Whole, and Person in Leibniz's Nouveaux Essais.

jeudi 30 septembre, 14h10-14h40

Résumé de la communication :

In New Essays II xxvii, Leibniz interacts with Locke's theory of identity and diversity.  In  this paper I shall explain two central and related matters that arise in the course of the discussion. 

First, "mereological essentialism" is the claim that each proper part is essential to its whole.  Both authors seem to endorse it, as neither is willing to allow a body to survive a change of its parts.  But there are significant differences in the metaphysical role the doctrine is allowed to play in their two systems.  I will try to clarify the differences, and in particular to place Leibniz's doctrine of part and whole into the overall context of his mature doctrine of the continuum and aggegates.

Second, Locke's concern with personal identity in this chapter gives Leibniz the opportunity to respond with his theory of corporeal substance.  I will explain the claims made here in light of his overall doctrine.  In the course of his remarks, Leibniz explicitly invokes the distinction between a substance and its organic body.  The organic body is merely a fancy aggregate but the substance has a soul or monad or principle of unity which is affixed to that body and carries identity with it.  With that distinction in place, Leibniz is much better positioned to accept mereological essentialism for aggregates and yet preserve the identity of living things over time despite their bodies' change of parts.  Locke, by contrast, has got only particles of matter organized into a "common life," and so seems committed by mereological essentialism to the counterintuitive notion that living things cease to exist the minute they have a change of parts.  In addition, Leibniz's claims here cannot be understood on typical "Idealist" or "monadological" theories, where the only substances are purely spiritual monads.  For if, as these theories would have it, aggregates are mind-dependent phenomena, they can't help constitute mind-independent substances as they must according to the claims made in the New Essays.

Along the way I shall put right some misinterpretations of these doctrines.  For instance, in Parts, Peter Simons rightly attributes mereological essentialism to Leibniz based on the New Essays, while Hans Burkhardt and Wolfgang Degen, in "Mereology in Leibniz's Logic and Philosophy" (Topoi 9: 3-13, 1990), wrongly take the case of animals to compromise it.