Scientific Realism and the Underdetermination Argument

One of the most influential arguments against the scientific realist’s position is the Underdetermination Argument (UD) which holds that every theory has indefinitely many empirically equivalent, but logically incompatible, rivals, and hence there is no rational epistemic basis for believing any theory to be true. In this paper, after explaining some general points about and presumptions of UD, the most important arguments for and against UD will be discussed. Then, it is argued that a modified version of scientific realism, called “entity realism” (ER) can be immune from UD, since it is only committed to the existence of some unobservables, but is agnostic about their theoretical descriptions (whatnesses). ER, however, would be an incoherent thesis if the existence/whatness distinction, and the Existentialist’s idea, according to which existence is fundamentally real, is rejected. The conclusion of this paper is that ER, supplemented with Existentialism, although is not an ideal stance, is the best secured position for scientific realists that worth fighting for.