Mihnea Dobre

Descartes is famous for his metaphysical foundation of his philosophical system. The image of the philosophical tree that he presents in the preface-letter to the French edition of the Principles of Philosophy (1647) offers a straightforward depiction of an organic growth of the philosophical system out of the metaphysical roots. This Cartesian metaphor was copiously exploited by the first Cartesians, who often attempted to represent Descartes's whole system as developing from metaphysical roots. However, the relations between metaphysics, physics, and the rest of the philosophical disciplines were deeply problematic. The book explores the difficulties of the alleged underpinning of Descartes’s physics into the metaphysics. It starts from Descartes’s own works, but expands into an investigation of the early reception of Cartesian physics in the French context. It gives an account of several first-generation Cartesians (Jacques du Roure, Géraud de Cordemoy, François Bayle, and Jacques Rohault), especially of how such figures discussed the passage from metaphysics to physics. The book offers a detailed discussion of the relevant writings of these authors, especially of those publications concerned with the foundation of natural philosophy and with its relation to metaphysics. The study of early forms of French Cartesianism is done also to refer back to Descartes, such that the solutions provided by his early followers are called to provide a better understanding of the philosophical problems identified in the writings of their more famous contemporary.

This chapter explores the intellectual development of Jacques Rohault – although not considered one of the leading figures of the early modern period, well known among historians of science. It attempts to evaluate Rohault’s Cartesianism and to present it in a more nuanced manner than it is usually illustrated in the literature. Focusing on his mature work, published only one year before his death in 1672, but also referring to his earlier activities in Paris and to the publication of his posthumous works, the chapter argues that his “Cartesianism” came rather late in his thinking, while his early activity concerns mathematics and mechanics. The reading endorsed in this chapter opens a fresh perspective on Rohault’s experimentalism, suggesting a transition from practical mathematics to Cartesian natural philosophy.

This article addresses the problem of Jacques Rohault’s Cartesianism. It aims to enrich the current portrayal of Rohault (1618–72) as a Cartesian natural philosopher concerned with experimentation. The modern evaluation of Rohault as an experimentalist can benefit from another explanatory layer, emphasizing the mathematical physics that shapes his natural philosophy. In order to argue for this complementary account, I focus on an early episode in Rohault’s career, represented by his reply to Fermat’s attacks against Descartes’s law of refraction (1658). The source has been discussed, so far, solely as part of the dispute in optics between Fermat and the Cartesians. The reading endorsed here explores the source from a different angle, suggesting an alternative account grounded on a more contextual understanding of Rohault’s contribution to Cartesianism. More diverse dimensions of Rohault’s intellectual formation are revealed, which in turn provides a more complex picture of this strain of Cartesian natural philosophy.

One of the most difficult, yet interesting change in theseventeenth-century natural philosophy was that of chemistry. This essayfocuses upon Cartesian re-evaluation of the philosophical disciplines,arguing that, from a systematic perspective, chemistry cannot find a place innatural philosophy. Chemistry, in its seventeenth-century form of“chymistry” shares a number of common features with other traditions andpractices. Descartes and his first-generation of followers discussed in thisessay – Jacques du Roure, Robert Desgabets, and Jacques Rohault – willreact precisely to this discipline of “chymistry,” opposing it to their physicsbuilt on a combination between theory of matter and mechanicalexplanations. The very restrictive Cartesian theory of matter will come intotension with any intermediate explanatory entity, such as the chymicalprinciples. This essay will investigate such tensions, arguing that they arecaused by both ontological and epistemological commitments. For example,the principles of the chymists contradict the one material extension of theCartesian world. At the same time, Cartesians require a more thoroughreductive process then the one provided by chymical explanations. In thissense, chymistry is good for practical purposes, but fails in providing anexplanation in natural philosophy and, hence, to represent a science.

The glass drop is a tear-shaped object with many curious properties. Although having a fragile tail, its main body is hard to break. On the other hand, breaking such a drop produces a loud noise and many very small particles of glass. In the seventeenth century, these objects became the focus of both experimental and natural philosophical investigation. In this article, I examine the ways in which various natural philosophers have dealt with glass-drops. This is neither a complete enumeration of the countless attempts to explain the object and its associated phenomena, nor a search for its origins. Rather, this study offers a glimpse into what was at stake in the inclusion of the glass drop—a new scientific object—into natural philosophy. I shall argue that a full description of the drop and of its properties required both experiment and speculation.