One True Cause: Causal Powers, Divine Concurrence, and the Seventeenth-Century Revival of Occasionalism by Andrew R. Platt (review)

On an old narrative, dating back to Leibniz and developed in nineteenth-century historiography, occasionalism was revived in the early modern period as an ad hoc response to the problems of mind-body union and interaction arising from Descartes's metaphysics. According to Leibniz, Descartes gave up the struggle, leaving his disciples to iron out this most scandalous of wrinkles in his system. A line of followers—Clauberg, Geulincx, La Forge, Le Grand, Arnauld, Cordemoy, and above all, Malebranche—dusted off the discredited doctrine of occasionalism in order to deal with the question of how unextended minds could interact with extended bodies. Plainly stated, the solution was as dissatisfying to Leibniz as it has been to most undergraduates since: my mind and my body do not really interact. Instead, typically, whenever my toe bangs into a door, God produces a pain sensation in my mind. And, typically, whenever I decide to raise my left arm, God creates a motion in the corresponding part of my body such that it rises. God is the only true cause of any event. Creatures provide mere occasions for God to exercise his causal power.

In the past forty-odd years, this story has been effectively challenged. Gary Hatfield and Daniel Garber argued that, apart from any considerations of mind-body relations, occasionalism is already entailed by Descartes's physics. Janet Broughton further argued that Descartes himself eventually abandoned the view that the body acts on the mind. Resisting occasionalist readings of Descartes, Michael Della Rocca, Dennis Des Chene, and Helen Hattab proposed concurrentist readings, on which Descartes remains closer to the dominant scholastic position that God and creatures are co-causes of finite effects. Meanwhile, a rich body of scholarship on Descartes's followers has revealed the diversity of motivations and strategies that led them to occasionalism. This literature makes it clear that occasionalism was a family of interestingly different positions, rather than a single, caricature view of God as puppeteer. Thomas Lennon, Steven Nadler, and Tad Schmaltz, among others, have shown, in particular, that the mind-body problem plays little to no role in Geulincx's, La Forge's, Cordemoy's, or Malebranche's arguments for occasionalism. Rather, they are led to occasionalism by more general considerations rooted in Descartes's substance-mode ontology and his causal principles. In just the last few years, several edited volumes have appeared on Descartes and occasionalism, including Chemins du cartésianisme (Antonella Del Prete and Raffaele Carbone, eds. [Paris: Classiques Garnier, 2017]), Occasionalism: From Metaphysics to Science (Matteo Favaretti Camposampiero, Mariangela Priarolo, and Emanuela Scribano, eds. [Turnhout: Brepols, 2018]), and the massive, fifty-essay Oxford Handbook of Descartes and Cartesianism (Steven Nadler, Tad Schmaltz, and Delphine Antoine-Mahut, eds. [Oxford: Oxford University Press, 2019]). Research on Descartes and Cartesianism has perhaps never been so vibrant.

Andrew Platt's fine monograph synthesizes a large swath of this scholarship to articulate some of its key lessons. It is divided into two parts. The first presents a very helpful analysis of historically plausible varieties of occasionalism in the context of later scholastic theories of cause, efficient causation, powers, and God's causal relation to the world (chapter 1); two chapters (2 and 3) on occasionalist and concurrentist readings of Descartes's physics and the mind-body problem (Platt sides with the latter camp on both issues); and a chapter (4) on the German "Cartesian-Scholastic" (to use Josef Bohatec's label, in Die Cartesianische Scholastik in der Philosophie und Theologie der reformierten Dogmatik des 17. Jahrhunderts [Leipzig: A. Deichert, 1912]) Clauberg's nonoccasionalist solution to the mind-body problem. Platt's main thesis in part 1 is that "there was more than one way for Descartes's followers to interpret and develop his philosophical views," so that occasionalism should not be seen as inevitable or logically forced upon them (7–8). Part 2 also consists of...