Filip A. A. Buyse

In Il Saggiatore (1623), Galileo makes a strict distinction between primary and secondary qualities. Although this distinction continues to be debated in philosophical literature up to this very day, Galileo's views on the matter, as well as their impact on his contemporaries and other philosophers, have yet to be sufficiently documented. The present paper helps to clear up Galileo's ideas on the subject by avoiding some of the misunderstandings that have arisen due to faulty translations of his work. In particular, it shows how Galileo's distinction directly implicates a novel understanding of physical bodies, which played an important part in his later condemnation by the Catholic Church. At the same time, the paper also argues that Galileo's distinction can already be found in the text and illustrations of earlier, popular Copernican writings.

Spinoza’s Principles of Cartesian Philosophy is often presented simply as an interpretation of Descartes’ Principia that does not reveal anything significant about Spinoza’s philosophy and its development. This paper, however, shows that Spinoza altered Descartes’ text in a way congruent with what he would later write in his Theological Political Treatise and the Ethics. More precisely, this paper concentrates not on what Spinoza added to Descartes’ texts but on how he presented them. The paper furthermore examines questions that were obviously important for Descartes but absent in Spinoza’s interpretation. Finally, this paper examines two concrete examples to show that Spinoza’s adaptations function as an unmasking of Descartes’ physics.