Tuesday, 15 November 2011
Hobbes on the Preservation of Motion
Kurt Smith, Department of Philosophy
Bloomsburg University
12:05 pm, 817R Cathedral of Learning

::: photos

Abstract: In the Principles, Descartes writes: “God is the primary cause of motion; and he always preserves the same quantity of motion in the universe.” It is in God’s immutable will that Descartes grounds the origin and conservation or preservation of motion and its quantity. Some scholars have taken Descartes’ claim about the preservation of motion to be a pre-Newtonian expression of inertia, most prominent in his first law, which speaks to the preservation of motion (independent of its quantity). We find a similar pre-Newtonian expression of inertia in De Corpore. Hobbes writes: “whatsoever is moved, will always be moved, except there be some other body besides it, which causeth it to rest” (DC, Part 2, Chapter xx, p.84). In Leviathan, he writes: “when a thing is in motion, it will eternally be in motion, unless somewhat else stays it” (L, Chapter II, Sect 1, p. 7); and, “when a body is once in motion, it moveth (unless something else hinder it) eternally” (L, Chapter II, Sect 2, p. 8). As some scholars see it, whereas Descartes can ground his first law in the immutable will of God, Hobbes, in providing no room in his physics for God, looks to have nothing to which he can appeal to ground the preservation of motion, let alone the quantity of motion. In this paper, I show that Hobbes has available a philosophical ground for the preservation of motion (the pre-Newtonian conception of inertia), located in De Corpore, in his discussions of cause and effect, and power and act.