Galileo and Reasoning Ex Suppositione

Abstract

Galileo has been seen, from the philosophical point of view, alternately as a Platonist whose rationalist insights enabled him to read the book of nature because it was written in ‘the language of mathematics,’ and as an experimentalist who used the hypothetico-deductive methods of modern science to establish his new results empirically (McTighe, 1967; Settle, 1967; Drake, 1970; Shapere, 1974). Both of these views present difficulties. In this essay I shall make use of recent historical research to argue that neither is correct, that the method utilized by Galileo was neither Platonist nor hypothetico-deductivist, but was basically Aristotelian and Archimedean in character. This method, moreover, was not merely that of classical antiquity, but it had been emended and rejuvenated in the sixteenth century, and then not by Greek humanist Aristotelians or by Latin Averroists but rather by scholastic authors of the Collegio Romano whose own inspiration derived mainly from Thomas Aquinas. Other influences, of course, were present, and these came from other medieval and Renaissance writers, but these need not concern us in what follows.