On the Question of Realism

Abstract

This essay engages the realism/instrumentalism debate in the philosophy of science. As she pursues her investigation of the world and our place in it, the Second Philosopher comes to believe in molecules and atoms based on evidence beginning with Perrin’s famous experiments on Brownian motion. This would seem to qualify her as a realist, but examination of the positions of leading instrumentalists van Fraassen and Stanford reveals that her claim to rational belief in unobservables on those grounds doesn’t amount to ‘realism’ as they understand it. This result suggests that the debate has gone astray.