This thesis examines the idea that when a physical theory contains symmetries, the theory should be interpreted in such a way that symmetry-related models represent the same physical state of affairs. It argues that we can best do so by drawing on analogies to ideas in philosophy of logic and language: specifically, by thinking of symmetries as a means of translating a theory into itself. It consists of six chapters, together with an introduction and conclusion.

In Chapter 1, I set ...