Locke and Cartesian Philosophy ed. by Philippe Hamou and Martine Pécharman (review)

The collected essays in Locke and Cartesian Philosophy, according to its editors, "advocate for a shift of emphasis" in the study of Locke and Descartes away from traditional questions related to their role in "the 'epistemological turn' of early modern philosophy" (3). Instead, "issues such as cosmic organization, the qualities and nature of bodies, the nature of ideas, [and] the substance of the soul" should receive more attention (3). The contributions address these questions as well as free will and Milton's detailed accounting of Locke's initial exposure to Descartes. The volume advocates for a shift in emphasis rather than a revolution by including several contributions in the traditional areas of the theory of ideas and epistemology. This is an excellent and engaging collection that makes its case well and is worth any early modern scholar's time. Each contribution deserves detailed engagement, but my discussion will be limited by space to two sets of contributions that exemplify the volume's spirit.

First, the contributions from Martha Bolton, Lisa Downing, and Philippe Hamou strike a chord around substance. Bolton's contribution is bold. She develops an anti-Aristotelian picture of Descartes and Locke by arguing that middle-sized objects are not substances for either. A familiar way to deny that mechanical bodies are Cartesian substances is to claim that there is only one extended substance. This is not Bolton's route, as she argues that there are indeed finite extended Cartesian substances. Mechanical bodies are not substances because they ontologically depend on such substances (and their modes). Similarly, nearly all of Locke's putative material substances turn out not to be substances, only corpuscles are. Middle-sized objects ontologically depend on arrangements—that is, modes—of these substances. At least concerning Locke, I was left wondering whether his conception of substance—a unifying principle through which the qualities of a thing exist—is weak enough to include such arrangements as substances.

The weakness of Locke's conception of substance is at the heart of Lisa Downing's contribution. Downing argues that Locke does not attack Descartes's conception of body for its inability to account for body's impenetrability. Locke was aware of Descartes's explanation of impenetrability through Descartes's correspondence with More, which was in Locke's library. (Downing's explication of Descartes's account of impenetrability in said correspondence is admirable.) Instead, Locke's attack stems from his objection to Descartes's claim that there cannot be both corporeal substance as well as merely extended substance. Such an argument presumes greater explanatory power in our understanding of substance than Locke thinks we are entitled to.

Philippe Hamou argues that the consciousness that defines Lockean persons deeply resembles Descartes's thinking substance. Hamou's interpretation of Locke has clear parallels to the Journal of the History of Philosophy 2016 Book Prize winner, Consciousness in Locke, by Shelley Weinberg, and shines in the commonalities it draws between such interpretations of Lockean consciousness and Descartes. Cartesian thinking substances and Lockean consciousness are always thinking (so long as they exist), intellectual, and indivisible. Excepting the label 'substance,' Lockean consciousness and Cartesian thinking substance are nearly indistinguishable.

Substance thus plays out in intriguingly different ways across these articles. For Bolton, Locke's conception of substance is robust enough to rule out middle sized objects as substances. For Downing, Locke's conception of substance is weak enough to be a basis for rejecting Descartes's substance dualism. For Hamou, Locke's conception of substance is robust enough to rule out that consciousness is a substance. Locke's insistence here is especially curious given that, as Downing argued, it is important to him that pure space might exist. These are novel and deep tensions in Locke's conception of substance, ripe for further research.

The second set of contributions focus on traditional comparisons between Locke and Descartes—ideas and epistemology. The articles exemplify the volume's spirit, however, in that they...