Abstract

It is argued that Galileo's theory of justification was a version of explanationism. Galileo's Dialogue on the Two Chief World Systems is to be read as primarily a defense of his theory of the tides. He shows how, by assuming Copernican motions, he can explain the tides, thereby justifying the endorsement of Copernicus. The crux of the argument rests on Galileo's account of explanation, which is novel in its reliance on the use of geometry. Finally, the consequences of his use of geometry, and his views on the limits of knowledge, force us to conclude that if Galileo was a realist, his realism was so highly constrained as to be irrelevant