Diderot, lecteur et interprete de Leibniz

Disenchantment with Cartesian rationalism and subject-object dualism is now over a century old. Over the last half century, as this disillusionment has become more pervasive and widely persuasive, philosophers and historians have also come to focus increased attention on those Western thinkers who foreshadowed this contemporary condition by standing outside and against the precise structures of Cartesian philosophy. Spinoza is one obvious example, for his vogue in recent years owes much to this broader philosophical realignment. Spinoza’s thought and career have attracted the attention of contemporary students as diverse as Jonathan Israel and Antonio Negri because for each Spinoza’s philosophy represents an alternative to the traditional strands of Cartesian dualistic Enlightenment. Leibniz has also attracted renewed philosophical attention in recent years for similar reasons, not least from Gilles Deleuze. And Diderot’s philosophy has likewise found new students as his particular brand of anti-Cartesian materialism, holism, and organicism has found itself comfortably realigned with contemporary philosophical sensibilities. Claire Fauvergue, a Paris-trained philosopher, is attuned to these changing hermeneutic impulses. In Diderot, lecteur et interprète de Leibniz she therefore gives us a meticulously detailed and closely argued study of how one influential intellectual encounter, that between Leibniz and Diderot, led to the assemblage of one of the eighteenth century’s most nuanced and powerful understandings of nature.

Fauvergue’s approach to her subject is meticulous and careful, perhaps to a fault. She begins by introducing the analytical concept of “convergence métathéorique” to capture the nature of the intellectual encounter between Leibniz and Diderot. She then applies this concept rigorously in a close reading of the two authors’ works. The virtue of “convergence métathéorique” as an analytical tool rests in its ability to hybridize the notion of direct, determined authorial influence on the one hand and free authorial appropriation on the other. Through the precise deployment of this complex framework in this case, Leibniz’s thought is shown not to have been a cause for Diderot’s, nor even to have been a trigger for Diderot’s own original inventions; rather, Leibniz’s philosophy is seen to have made Diderot’s possible by providing him with much of the conceptual and metaphysical material from which he then built his own understanding. From this complex, and ultimately illuminating, vantage point, Leibniz neither becomes the singular source for Diderot’s ideas, nor the cause for his thought in any linear or causally determinative way.  Instead, Diderot appropriates, reinterprets, modifies, and in many cases even reinvents Leibniz’s thought while ultimately carrying the substance of Leibniz’s earlier work into his own original philosophy. In this way, what he produces is neither wholly original nor a hybrid neo-Leibnizianism, but an original creation that nevertheless contains within it an important set of Leibnizian legacies.

Fauvergue’s study of the precise “convergence métathéorique” between Leibniz and Diderot thus provides a powerful framework for thinking generally about the relation between tradition and innovation, and influence and invention in the development of philosophical thought. It also produces a rich perspective from which to understand Diderot’s natural philosophy. Central to the meta-theoretical convergence that Fauvergue analyzes is Diderot’s transformation of Leibniz’s Baroque rationalist metaphysics into a more modern (which is to say empirico-scientific) materialism. The steps in this creative transformation are documented in meticulous detail – indeed the substance of the book is largely devoted to a careful and close analysis of these philosophical transformations. But the overall results can be summarized succinctly. In brief, whereas Leibniz resisted a fully materialist and monist conception of nature, and worked hard to show how the material world was governed by immaterial principles beholden to transcendental logics of rationality and teleological purpose (eg. Leibniz’s notion of the pre-established harmony, or his conception of the principle of sufficient reason),  Diderot, reading Locke and the Newtonians alongside Leibniz and Spinoza, transformed the rationalist metaphysics of Leibniz into a contingent and empirico-scientific monist materialism, one without guiding teleologies and immanent logics.

The constituent steps in this precise philosophical transformation must be gleaned from a close reading of Fauvergue’s very tightly argued book. Yet in my judgment, the transformation is richly documented and impeccably demonstrated, such that one is left with both a deeper and more precise appreciation of Diderot’s natural philosophy, as well as with a similarly renewed appreciation for Leibniz’s. One also comes away from the book with a deeper historical understanding of eighteenth-century philosophy as a whole. For beyond what it has to say about Diderot’s precise relationship to Leibniz, the argument overall also points to Leibniz’s important role in preparing the ground not only for Diderot’s philosophy, but also for much of the radical materialist philosophy of the age of Enlightenment more generally.

This last claim may strike a discordant note with many dix-huitièmistes who continue to share Voltaire’s perception of Leibniz (and German metaphysics more generally) as the beacon of everything that was retrograde and un-radical about the eighteenth century. Fauvergue’s analysis shows us why this prejudice needs to be revised. Diderot certainly shaved off most of Leibniz’s Baroque sensibilities in his creative appropriation of his philosophy, but what Fauvergue’s notion of meta-theoretical convergence rightly insists on is the substantial philosophical continuities that nevertheless survived this pruning. Diderot’s philosophy was certainly not neo-Leibnizian, but it was Leibnizian in crucial, constitutive ways. Accordingly Fauvergue’s book contributes in important, if unacknowledged, ways to the recent, and to my mind very salutary, trend toward re-establishing Leibniz’s constructive and progressive role in the development of modern Enlightenment philosophy, particularly its materialist, monist, and organicist strands. Deleuze, for example, found in Leibniz a progenitor of the contemporary philosophies of nature (including his) that strive to liberate matter, life, and reason from the sterile and reductive binaries of Cartesian dualism and mechanism. Fauvergue’s book adds substance to such explorations by showing the deep ties that bound Leibniz to Diderot, a thinker whose connection to these contemporary philosophical positions is less in need of recognition.

Indeed, if Diderot, lecteur et interprète de Leibniz has a weakness, it rests in its inability to bring the particular textual demonstrations it offers into dialogue with this broader philosophical reinterpretation of Enlightenment thought as a whole. Fauverge’s sense of rigor, for example, leads her toward painstaking efforts at guaranteeing the empirical authenticity of the philosophical connections she sees. No claim of intellectual interaction is allowed to stand without a precise empirical link anchoring it, and the book’s footnotes and bibliography, beyond recording all of her meticulous empirical and textual work, position the text narrowly within the discussions of a very small community of French philosophers alone. To be fair, the book is a thesis cum philosophical monograph produced through a process of professional formation. Its narrowness, therefore, can very justifiably be explained by the professional imperatives that brought the book into being. Many of its most illuminating textual insights, moreover, are a consequence of its insistent rigor, and thus a different framework may well have produced a less illuminating set of results. Yet since the significance of the convergence between Leibniz and Diderot that the book unravels far transcends its precise scholarly address, this reviewer could not help but feel a sense of frustration at the gap between the two perspectives.

Diderot, lecteur et interprète de Leibniz is without question frustratingly narrow in scope, but it is also richly insightful within its self-imposed limits, and especially productive in deploying its preferred method of rigorous inter- and intra-textual analysis in incisive ways. And since the book also speaks, however unwittingly, to crucial reconfigurations going on within Enlightenment studies and contemporary philosophy more generally, it can be recommended enthusiastically as a precise monographic treatment of one particular, if deeply fecund, encounter in the making of modern thought.