In this chapter, we present the concept of force in Kepler. We follow the
development of this concept during Kepler’s scientific career, starting from his early
considerations in the Mysterium Cosmographicum (1596) until his ripest conceptions
expounded in the Epitome Astronomiae Copernicanae (1618–1621). Kepler
tried to supply a dynamical explanation to the planetary movements. This is an
important novelty because astronomy was traditionally a kinematical science. Based
on the main accredited literature we present a historical account and theoretical/
nature of science (NoS) developments: (1) Keplerian forces; (2) physical astronomy;
and (3) orbits, force, and the relation between distances and forces. Koyré had
a prominent role in the studies on astronomical revolution and on Kepler. He was
also important in fully clarifying the pivotal function that physical astronomy—and
hence the concept of force—had in Kepler’s system of the world. Indeed, Koyré is
still nowadays an almost unavoidable reference point for Kepler’s Forschung. We
refer to several interpretations of his. This is the reason why we think appropriate to
present this work in homage to Alexandre Koyré.
