Leibniz's Metaphysics: Its Origins and Development (review)

Christia Mercer's massive study is aimed at unearthing the hidden roots of Leibniz's metaphysics by placing the German philosopher back in the intellectual context within which his thought first took shape. In so doing she stresses the fundamental importance of Leibniz's early years for the development of his philosophy. In particular she convincingly argues for the key role played by Leibniz's early exposure to the thought of eclectic thinkers (including his teachers) who were trying to build a new philosophical synthesis centered around the key tenets of Christian theology and combining elements of Aristotelianism, Platonism, and (in at least some cases) the new mechanical philosophy of nature.

One of Mercer's central theses is that the methodological and metaphysical commitments that Leibniz developed during his youth formed the bedrock of his mature philosophy (23). More precisely, her bold claim is that Leibniz's core metaphysics (including the complete concept account of substance) was constructed in 1668-71, re-examined and slightly developed in 1672-79, and then used for the rest of his long philosophical career (18, 470). The key inspirational forces driving the development of Leibniz's philosophy, in her view, had even earlier origins. In the mid-1660s Leibniz did not yet have a fully formulated metaphysics; but he already possessed very definite philosophical objectives which were to guide the development of his metaphysics and form the unstated assumptions underlying his mature thought (40). Mercer identifies these unstated assumptions as a "Metaphysics of Method," a "Metaphysics of Substance," and a "Metaphysics of Divinity," all of which she finds fully developed in his early thought (468-9).

According to Leibniz's "Metaphysics of Method" (examined in part I), there exists a truth beneath the prominent philosophical schools which can and ought to be discovered. This conciliatory methodology was Leibniz's answer to the political, religious, and philosophical chaos around him. He was deeply convinced that his brilliantly original eclectic metaphysics would provide the foundation of philosophical, theological, and even political peace. Leibniz's "Metaphysics of Substance," Mercer argues in part II, melded an Aristotelian approach to substance with a mechanical physics and originated at the very outset of his intellectual carrier in an attempt to solve specific theological problems (e.g., those of the incarnation and resurrection). Platonism in turn offered the material for Leibniz's "Metaphysics of Divinity" (explored in part III), that is, for his conception of the relationship between God and creatures. The fourth and final part of Mercer's book takes her analysis of Leibniz's writings up to 1679 and describes the laying of the foundations of his mature metaphysics. She concludes not only that Leibniz proposed the doctrine of pre-established harmony prior to his departure for Paris in March 1672, but also, more generally, that the other tenets of Leibniz's mature thought, including his theory of truth, grew naturally out of his early metaphysics (see, in particular, 2, 15-8, 47, 52, 169-70, 250-2, 300-1, 472).

Throughout the book Mercer describes her interpretation as "startling," "unfamiliar," "dramatic," and "surprising," and fears that "readers may balk" at her conclusions since "so much of Leibniz's thought has escaped us for so long" (see, for instance, 1, 9, 471). Some readers may feel, on the contrary, that she has underestimated the extent to which several of her central theses—such as the importance of the earliest stages of Leibniz's philosophical development in general and of eclecticism, theological problems, and Platonism, as well as Aristotelianism within that development in particular—are already reflected in the best recent traditions of international Leibniz scholarship. But her book undoubtedly breaks new ground and remains an important contribution to an exciting field which cannot and will not be ignored. While international Leibniz scholarship may not absorb some of this book's more...