Marleen Rozemond

Descartes's dualism, and his argument for it, are often understood in terms of the modal notion of separability. I argue that the central notions, substance and real distinction, should not be understood this way. Descartes's well-known argument for dualism relies implicitly on views he spells out in the Principles of Philosophy, where he explains that a substance has a nature that consists in a single attribute, and all its qualities are modes of that nature. The argument relies ultimately on a deeply rationalistic view of substance.

One question that has created controversy among interpreters is just how much is in doubt at the end of the Dream Argument in Meditation I. I argue that there is doubt about the existence of composite bodies not yet about the existence of a physical world. I also caution against using later parts of the Meditations to interpret the First Meditation on account of the order of reasons in this work. I connect the Omnipotent God argument to Descartes's views about innate ideas and analyze the First Meditation in relation to Descartes's anti-aristotelian purposes.

In the Monadology Leibniz has us imagine a thinking machine the size of a mill in order to show that matter can’t think. The argument is often thought to rely on the unity of consciousness and the notion of simplicity. Leibniz himself did not see matters this way. For him the argument relies on the view that the qualities of a substance must be intimately connected to its nature by being modifications, limitations of its nature. Leibniz thinks perception is not a modification of matter because it is active and matter is passive. At the same time, there are traces in Leibniz of a different argument that relies on the notion of internal action, which may involve the notion of simplicity. Critics have sometimes charged that the Mill Argument is an argument from ignorance, but Leibniz was aware of this problem and made clear that he did not make that mistake.

In recent years more and more scholars of early modern philosophy have come to acknowledge that our understanding of Descartes’s thought benefits greatly from consideration of his intellectual background. Research in this direction has taken off, but much work remains to be done. Dennis Des Chene offers a major contribution to this enterprise. This erudite book is the result of a very impressive body of research into a number of late Aristotelian scholastics, some fairly well known, such as Suárez, others quite obscure. Two thirds of the book is devoted to the Aristotelians, with occasional references to Descartes; the last third focuses on Descartes, although there still much Aristotelian ground is covered. Des Chene indicates three major themes for his book: natural change and agency, the structure of material substance, and finality.

Descartes held that the human mind or soul is indivisible, unlike body. In this paper I argue that his treatment of this feature of the soul is intimately connected to his engagement with Aristotelian scholasticism. I discuss two strands in Descartes. There is a long tradition of arguing for the immortality of the human soul on the basis of this view. Descartes did use this view in defense of dualism, but I argue that he held that the soul’s immortality should be established rather on the basis of its status as a substance. This line of thought, I contend, is connected to his rejection of (most) Aristotelian substantial forms. Furthermore, the indivisibility of the human soul emerges repeatedly in connection to the union and interaction of mind and body in ways that connect to Aristotelian scholastic treatments of these issues.

Early modern philosophers rejected various important aspects of Aristotelianism. Current scholarship debates the question to what extent the early moderns rejected final causation. Leibniz explicitly endorsed it. I argue that his notion of final causation should be understood in connection with his resurrection of substantial forms and his seeing such forms on the model of the soul. I relate Leibniz’ conception of final causation to the Aristotelian background as well as Descartes’s treatment of teleology. I argue that he agreed with a view found in Aristotelianism that genuine efficiently causal powers require immanent teleology and with Descartes that immanent teleology presupposes cognition in the agent.