Abstract

Christia Mercer’s magnum opus, Leibniz’s Metaphysics: Its Origin and Development, long awaited, is finally about to appear from Cambridge University Press. It was well worth the wait. The book is impressive in the wealth of detailed argumentation and historical background that fills the work. Mercer’s general thesis is still that Leibniz’s mature thought emerges from a view that Leibniz shares with his teachers, an eclectic philosophy that sees truth lurking in many places, and that he sees the task of the philosopher as mining the past for its truths, and showing how the different philosophies can be made consistent with one another and made into a single system. As in her earlier work, the resolution of the conflict between Aristotelianism and the new mechanism is important. But Mercer also claims to have discovered something else utterly unexpected, a strong Platonistic strain in seventeenth-century German thought. While Aristotelianism and mechanism may have dominated thought about the physical world, Mercer has discovered strongly Platonistic strains in the conception of God and the soul, both in the young Leibniz and in his teachers. Even more surprising, Mercer argues that the main tenets of Leibniz’s mature thought emerged out of this mixture, and did so as early as 1670 and 1671. In particular, she argues that both the pre-established harmony and the idealism characteristic of his mature thought emerged in these years, as the result of an attempt to harmonize different elements of Aristotelian, Platonic, and mechanist philosophies, in response to particular problems in philosophy, theology, and even physics that gripped him at that time. If she is right, this will fundamentally alter our view of Leibniz.