Abstract

This paper provides the framework for understanding Galileo’s request to the Grand Duke of Tuscany, in 1610, to be appointed in Florence as both Mathematician and Philosopher. By explicitly choosing such a title, he wished to stress the fact that his own work aimed at contributing to the new physical astronomy with which Copernicus inaugurated what is now called the Scientific Revolution. As opposed to Ptolemy, who understood astronomy as a purely mathematical tool in order to “save the phenomena” and allow for accurate predictions, Galileo – very much in line with Copernicus and Kepler, as well as Newton after him – supported the reality of the Copernican system not only against Aristotle and Ptolemy, but also against Tycho Brahe. And, as it turned out after 1616, against the Church itself, which, in full accord with Osiander’s unsigned preface to the De revolutionibus, refused to see in the Copernican theory anything more than a mere working hypothesis to which astronomers were allowed to appeal only for computations