The Underdetermination of Theories and Scientific Realism

The empirical underdetermination of theories is a philosophical problem which until the last century has not seriously troubled actual science. The reason is that confirmation does not depend only on empirical consequences, and theoretical virtues allow to choose among empirically equivalent theories. Moreover, I argue that the theories selected in this way are not just pragmatically or aesthetically better, but more probably (and/or largely) true. At present in quantum mechanics not even theoretical virtues allow to choose among many competing theories and interpretations, but this is because none of them possess those virtues to a sufficient degree. However, first, we can hope for some future advancement (new empirical tests, or new theories). Second, even if no further progress came forth, all the most credited competitors agree on a substantial core of theoretical assumptions. Therefore underdetermination does not show that we cannot be realist on unobservable entities in general, but at most that in particular fields our inquiry may encounter some de facto limits.