Abstract

There is widespread consensus that a view of nothing but powers or dispositional fundamental properties struggles to accommodate physical symmetries. An option is to expand the fundamental ontology admitting extra modal elements constraining the behaviour of physical systems. Another is to eliminate symmetries altogether deeming them as dispensable structures. Either option is problematic. The expansion strategy yields a problematic ontological inflation that undermines the explanatory ambitions of the powers view. The eliminativist approach, if unsupplemented, does not deliver a naturalistically respectable view of symmetries and their role in contemporary physics. To avoid these problems, Samuel Kimpton-Nye (2023) has recently defended a promising solution to ground symmetries in powers taken collectively by defending a non-Humean Best System Account of nomic items. This paper critically examines Kimpton-Nye’s view of symmetries. We argue that it raises metaphysical and scientific concerns regarding their powerful grounds of symmetries and their physical features. As a more promising alternative, we argue for combining an ontology of fundamental powers with a deflationist account of symmetries. In contrast to Kimpton-Nye’s proposal, symmetries are not grounded collectively in powers, but they are epistemic, rule-prescribing principles in the Best Systems. Embracing the resulting view, we hold, is a better way to be a power theorist about symmetries.