Conatus - in Descartes

In Descartes

In the first half of the seventeenth century, René Descartes (1596–1650) began to develop a more modern, materialistic concept of the conatus, describing it as "an active power or tendency of bodies to move, expressing the power of God". Whereas the ancients used the term in a strictly anthropomorphic sense similar to voluntary "endeavoring" or "struggling" to achieve certain ends, and medieval Scholastic philosophers developed a notion of conatus as a mysterious intrinsic property of things, Descartes uses the term in a somewhat more mechanistic sense. More specifically, for Descartes, in contrast to Buridan, movement and stasis are two states of the same thing, not different things. Although there is much ambiguity in Descartes' notion of conatus, one can see here the beginnings of a move away from the attribution of desires and intentions to nature and its workings toward a more scientific and modern view.

Descartes rejects the teleological, or purposive, view of the material world that was dominant in the West from the time of Aristotle. The mind is not viewed by Descartes as part of the material world, and hence is not subject to the strictly mechanical laws of nature. Motion and rest, on the other hand, are properties of the interactions of matter according to eternally fixed mechanical laws. God only sets the whole thing in motion at the start, and later does not interfere except to maintain the dynamical regularities of the mechanical behavior of bodies. Hence there is no real teleology in the movements of bodies since the whole thing reduces to the law-governed collisions and their constant reconfigurations. The conatus is just the tendency of bodies to move when they collide with each other. God may set this activity in motion, but thereafter no new motion or rest can be created or destroyed.

Descartes specifies two varieties of the conatus: conatus a centro and conatus recedendi. Conatus a centro, or "tendency towards the center", is used by Descartes as a theory of gravity; conatus recendendi, or "tendency away from the center", represents the centrifugal forces. These tendencies are not to be thought of in terms of animate dispositions and intentions, nor as inherent properties or "forces" of things, but rather as a unifying, external characteristic of the physical universe itself which God has bestowed.

Descartes, in developing his First Law of Nature, also invokes the idea of a conatus se movendi, or "conatus of self-preservation". This law is a generalization of the principle of inertia, which was developed and experimentally demonstrated earlier by Galileo. The principle was formalized by Isaac Newton and made into the first of his three Laws of Motion fifty years after the death of Descartes. Descartes' version states: "Each thing, insofar as in it lies, always perseveres in the same state, and when once moved, always continues to move."