Underdetermination—where two different theories give the same predictions—is rarely an all-or-nothing affair, because the distinction between theoretical and observational claims is blurry. Apparent cases of underdetermination often get resolved over time as one theory turns out to be more powerful as a framework. The only realistic cases of exact underdetermination seem to be where two theories are mathematically equivalent; in these cases, physicists—and some, but not all, philosophers of physics—regard them as the same theory.
underdetermination
