Philoponus in Galileo’s Early Works.

This paper addresses Philoponus’ possible influence on Galileo’s Iuvenilia and De motu antiquiora. For in these early works Galileo confronts Aristotelian cosmology and its critics more directly. In his Iuvenilia, Galileo deals with the heavens’ incorruptibility, the nature of celestial matter and the elements. Philoponus is one of the philosophers most frequently mentioned, right after Plato, Aristotle, and Averroes. In this regard, Galileo focuses on two points: the inadequacy of the notions of ‘matter’ and ‘form’ to explain the nature of the heavens, and the reduction of gravitas and levitas to instrumental principles (principia instrumentaria) to describe motion. In his Iuvenilia, Galileo discusses the activity of the elemental fire, which is credited with both circular and rectilinear motions. The Iuvenilia are then related to De motu, where fire is also mentioned in relation to natural and violent motions. In Galileo’s De motu, Philoponus is only mentioned in two occasions, but there are good reasons to see a connection with his Iuvenilia.