Journal of the History of Philosophy

The principle of "organism"—of intrinsic and dynamic unity—and the existence of "organized bodies"—of living things—in the physical world represented crucial preoccupations for philosophers of nature and experimental naturalists across the eighteenth century. How to make sense of these in a manner consistent with a unified scientific understanding of the physical world became the inevitable challenge that accompanied these recognitions. In just this theoretical enterprise, Leibniz emerges to historical scrutiny as an indispensable and pervasive influence. Thus, we are very fortunate to have the body of scholarship that François Duchesneau has devoted to this topic over the course of his illustrious career. In this new and impressive contribution, he proposes to "retrace the methodological and doctrinal impact [of Leibniz] in the century of Enlightenment and up to the dawning of biology in its own terms, if not beyond" (13). His thesis is: "this Leibnizian model was without a doubt a sort of common denominator for the diverse theoretical propositions which endeavored to criticize, to adjust, to adapt, even radically to transform it" (15). Thus, the key issue is the reception of Leibniz—sometimes explicitly affirmative, sometimes explicitly critical, but often and most interestingly implicit or disguised, yet nonetheless seminal. Accordingly, we read of various "neo-Leibnizian" or "anti-Leibnizian" stances, all of which, obviously, require Leibniz as interlocutor. The itinerary of the inquiry is extended and intricate: starting from Leibniz's own views on "organism" as articulated in controversies with Bayle, LeClerc, and most extensively Stahl, at the outset of the eighteenth century, to the "terminus ad quem" (20), as Duchesneau construes Kant, at its close. While Duchesneau includes the self-avowed Leibnizian "school" of Wolff and makes very interesting use of a late Wolffian, Hanov, the most compelling line of reception flows through Bourguet to Buffon, Maupertuis, Diderot, and Needham, and then to their rivals, Haller and Bonnet, to culminate in a familiar linkage of Blumenbach with Kant. The readings are, in every instance, meticulously detailed, and the measured effort to discern Leibnizian residues always consistent, if not always equally convincing.

Duchesneau aims, without stridence, to undercut the notion that "experimental philosophy" on the model of Newton and Locke precluded this Leibnizian reception, and his case is just. To honor the nonetheless salient presence of this "experimental philosophy," he not only recalls his earlier demonstrations of Leibniz's own affirmative stance toward the "microstructuralism" of seventeenth-century experimentalists like Malpighi, but gives rich accounts of the actual experimental practices and conjectures of the eighteenth century—for example, "fiber" theory, the bewildering properties of Trembley's polyps, the highly contested experimental reports of Needham and Buffon regarding infusoria, and Haller's distinction of the life forces of irritability and sensibility. Against just this rigorously experimental-theoretical backdrop, Duchesneau is then able to demonstrate the recourse to Leibnizian conceptualizations in order to resolve certain theoretical impasses that arose immanently in the scientific practices.

The most important result, in my view, is that Duchesneau establishes a pervasive naturalization of the Leibnizian conceptualization of organism. What does that betoken? [End Page 762] First, it suggests that the practices of life science sought, in the terms of Kant, to "minimize appeal to the supernatural" (Critique of Judgment, §81). Hence, "naturalization" was an endeavor to lower the metaphysical cost associated with the various theories of organism. Yet, at the same time, strictly deriving the living from the general laws of physics remained largely inconceivable—even for many materialists, who thus had to become "vital" materialists! In seeking to render the indispensable purposiveness of organisms immanent to nature, the philosophers and experimentalists of the eighteenth century had to insist both that (Leibnizian) entelechies had some measure of empirical indispensability—hence constructions like "physical" or "physiological" monads abounded in their conjectures—and, concomitantly, that nature had to be understood as more capacious and intrinsically dynamic ("vital") than the mechanistic materialists of an earlier day presumed. At the close of the century, Kant stipulated that naturalists had...