The 2016 James T. Cushing Memorial Prize in History and Philosophy of Physics was awarded to Dr. Adam Caulton, currently assistant professor at the Munich Center for Mathematical Philosophy, for his paper, “The Role of Symmetry in the Interpretation of Physical Theories,” published in Studies in History and Philosophy of Modern Physics (2015).
Symmetries and analytic postulates: a framework for interpreting physical theories
It is widely accepted that the identification of a physical theory’s symmetries — roughly speaking, transformations defined in the theory’s formalism which preserve all the values of some salient set of quantities — is a project that is intimately connected to the project of identifying which quantities in a theory’s formalism represent “genuinely physical” properties and relations. The connection is supposed to be this: all physical quantities are preserved under the symmetries, and in this way they determine each other. And yet it is also widely accepted that symmetries encapsulate general and highly non-trivial empirical truths (as in the case, for example, of the relativity principle in the special theory of relativity). But how can a symmetry preserve all physical quantities, while at the same time having interesting empirical implications?
In this talk, I present a framework for making sense of these rival roles for symmetries in physical theories. The inspirations for this framework are many, but borrow chiefly from Carnap: in particular his conception of a theory’s “analytic postulate”, which serves to constrain the interpretation of the terms of a formal theory. I give Carnap’s proposal a semantic setting, along the lines of van Fraassen and Beth, and defend the fruitfulness of something like (but not quite identical to) an analytic/synthetic distinction for the purposes of theory interpretation. Amongst other things, this distinction serves to separate those symmetries which reveal representational redundancies and those which have important empirical implications.