The dark matter problem in astrophysics exposes an underappreciated weakness in the evidential warrant for General Relativity (GR). The "dark matter double bind" entails that GR gets no differential evidential support from dynamical phenomena occurring at scales larger than our solar system, as compared to members of a significant class of rival gravitation theories. These rivals are each empirically indistinguishable from GR for phenomena taking place at solar system scales, but make predictions that may differ radically from GR's at larger (...) scales. Thus the typical confidence in the universal applicability of GR is insufficiently warranted in the present evidential context. (shrink)