ABSTRACT
Realists suggest that acceptance of a mature and genuinely successful theory should be identified with belief that the theory is approximately true. Some empiricists, however, counter that there is a simple argument against the realist thesis: the argument from the underdetermination of theories by evidence (henceforth, UTE). It goes like this: two theories which are observationally indistinguishable, i.e. they entail exactly the same observational consequences, are epistemically indistinguishable, too, being equally well supported by the evidence. Hence, the argument concludes, there are no positive reasons to believe in one rather than the other. This conclusion is what Laudan very aptly has called the egalitarian thesis (1996:33). Since, the argument goes on, for any theory which entails the evidence there are incompatible but empirically indistinguishable rivals, it follows that no theory can be reasonably believed to be (approximately) true.
