Underdetermination and Scientific Realism

It is claimed that the underdetermination of scientific theories by empirical data can undermine the position of scientific realism. Believing in the (approximate) truth of mature scientific theories, scientific realists believe that we can know the unobservable level of the world based on the ontologies of these theories. But this belief has been challenged by relying on the underdetermination thesis. It has been said that since there are numerous equivalent theories for each scientific theory that, despite presenting different ontologies, they are all equally consistent with observational evidence, any realistic belief in the truth of any theories would not have any epistemic support. To overcome this challenge, realists need to show that we have epistemic ways other than the direct confirmation by observational evidence that can break such an underdetermination. In this article, after carefully delineating the problem, we will try to show that it is possible to answer this question by relying on an approach we call "development of confirmation resources". According to this approach, theories can also be confirmed by other sources. The most important resources presented so far are: indirect confirmation and theoretical virtue. After evaluating indirect confirmation, in favor of this claim we will argue, beyond empirical consequences, theoretical virtue, especially "explanatory power", can serve better as the source of confirmation that realists need. Of course, the usage of theoretical virtue has always been challenged, but, in the final sections of the paper, we will show that these challenges can be answered.