Karen Detlefsen

This dissertation is an examination of the emergence of the preformation doctrine of generation in three early modern philosophers: Descartes, Malebranche and Leibniz. Received wisdom on this question maintains that the preformation doctrine became so popular in the seventeenth century because it seemed most capable of explaining generation of living beings within the limits of the reigning mechanical philosophy. This dissertation considers another motivation, generally neglected by commentators, for the rise of this doctrine in the early modern period---namely to account for the individuation, unity and enduring identity of material bodies. ;With the clear exception of Leibniz, early modern rationalists rarely developed robust theories of material individuation, but I argue that the living, organic being is a paradigm example of the enduring material unity for all three philosophers under examination. Descartes' theory of generation, however, is unable to account for the unity of this living being, although it is able to account for species-specific complexity even given the nascent mechanism that he embraced. So Malebranche introduces preformation as a way to remedy this failure. ;Nonetheless, both Descartes' and Malebranche's forms of mechanism threaten the material unity of organisms on a number of fronts. Leibniz's starting point, I argue, is the problem of individuation very broadly conceived, and his solutions to the various aspects of this problem all dovetail to culminate in his quite unique theory of preformation and in a notably different version of mechanism than that held by his predecessors. ;All three thinkers draw on Aristotelian ideas about substantial unity and organic beings, though they do so in different ways. I thus show that the usual story of the early moderns' radical break from Aristotelianism crumbles under a consideration of the individuation of living individuals. I also argue that teleology enters into all three philosophers' work more than normally supposed. Finally, I use my findings to suggest new ways of looking at central metaphysical questions of the seventeenth century and new ways of reading the historiography of generation in the early modern period