ABSTRACT
Alexandre Koyré praised Gassendi for having published the first correct formulation of the principle of inertia thanks to his “deep understanding” of Galileo’s science, but also criticized him for his distrust of mathematics and his physics made of “bits and pieces.” Taking its cue from Koyré’s ambivalent judgment, this chapter provides a reconstruction of Gassendi’s engagement with Galileo’s new science, starting with the De motu impresso a motore translato epistolae duae (1642) and ending with the Syntagma philosophicum. The chapter focuses on three themes: Gassendi’s account of free fall and projectile motion; his formulation of the principle of inertia; and his reinterpretation of Galileo’s theory of tides. More specifically, it deals with Gassendi’s project to provide Galileo’s laws of motion with an ontological foundation; analyzes his attempt to bridge the gap between the principle of inertia, valid at the level of the res concretae, and the theory of the self-motion of atoms; and tries to make sense of Gassendi’s simultaneous endorsement of Galileo’s theory of tides, on the one hand, and of Kepler’s laws of planetary motion, on the other. The chapter also shows that Gassendi was aware of some conceptual tensions in his theories, which he partially modified over the course of his career.
