A quo moventur planetae? : Kepler et la question de l'agent du mouvement planétaire après la disparition des orbes solides / Miguel A. Granada.
Abstract:
"A quo moventur planetae?" After the elimination of the solid orbs: Kepler and the question of the agent of planetary motion. The elimination of the celestial spheres in the 1580s raised the question of the agent of planetary motion. Against the general conception that the planets moved by virtue of an internal principle (through their intelligent souls), Kepler elaborated between 1593 (the date of a dissertation in Tubingen defending the motion of the Earth) and 1609 (the year of publication of the Astronomia nova) a celestial physics which accounted for planetary motion throught the action of physical principles, mainly the motive force of the Sun. This celestial physics dispensed with intelligent internal principles of planetary motion. The present article focuses on the progressive construction of this system of plysics up to 1609 and on Kepler's criticism of the possibility that planetary motion was the product of an internal intelligence. As evidenced by De stella nova (1606), this criticism did not exclude the existence of souls in the heavenly bodies in order to account for a plurality of phenomena beyond simple planetary motion. Rather, it followed the construction of the new physics and was subordinated to it. At the same time, Kepler's criticism was closely related to the 'rhetorical' needs that conditioned the presentation of his new astronomy to the public.
Galilaeana A. 7 (2010), p. 111-141