Local and Global Relativity Principles

Abstract

Local versions of the (special) principle of relativity say that if the same type of experiment is conducted in two isolated, unaccelerated laboratories, then the outcomes of those experiments must be the same. Global versions of the principle say that if you take a physically possible world and boost the entire material content of that world, you get another physically possible world. Some authors say that the local and the global principles are logically independent, and that the local version is more important. These authors are wrong. I argue that the global version entails the local version, and discuss why a counterexample to this entailment offered by Tim Budden fails.