Meeting 1: Cristian López and Valeriya Chasova on Symmetries in Physics
Channel: CEFISES at UCLouvain
Date: 2021-03-25

[REUPLOAD] Recorded online, March 17, 2021. Abstracts of the two talks:

Cristian López — Against symmetry fundamentalism, in defence of symmetry deflationism

In this presentation I argue that symmetry fundamentalism, pace naturalistic metaphysicians and some philosophers of physics, is not an adequate view to construe the role that symmetries play in physics. I do this by introducing symmetry deflationism as a more adequate contrasting view. According to symmetry deflationism, symmetries are neither aspects of fundamental reality nor guides to our ontological commitments. Rather, they play just a heuristic role in theory construction, providing general rule-prescribing principles to build the dynamics and to comprehend the nature of forces in physics.

The main reason for supporting symmetry deflationism rather than symmetry fundamentalism, I submit, is a (sometimes overlooked) tension between two opposing views on how symmetries become established within a physical theory: either by stipulation or by discovery. I claim that the by-stipulation view not only is dominant in today’s physics, but also captures philosophically well the role that symmetries play in physical theorising. However, I contend that symmetry fundamentalism conflicts the by-stipulation view. Therefore, by overloading the ontological import of symmetries symmetry fundamentalism fails to capture the role that symmetries play in modern physics. I hence claim that symmetry deflationism, instead of symmetry fundamentalism, should be adopted.

Valeriya Chasova — A gradation of empirical statuses for conservation principles

Kosso [2000, BJPS] introduced two ways for theoretical symmetries to be empirically meaningful, called direct and indirect empirical status (DES and IES). These have been thought to obtain through the links of theoretical symmetries respectively with empirical symmetries and with conservation laws. However, I show that conservation principles, i.e.derivations of conservation laws from theoretical symmetries, make us overcome the binary DES/IES distinction in favour of a gradation. Moreover, conservation principles involve not only IES but also DES.

Indeed, more precisely theoretical symmetries have IES when they entail theoretical conservation laws which correspond to empirical conservation laws in the world. So, in the case of IES the link between theoretical symmetries and the world is mediated by theoretical conservation laws, while in the case of DES it is immediate (at least on my analysis of DES). I suggest that this kind of mediation between the theoretical element of interest and the world is what makes an empirical status indirect, and that indirectness can be measured in terms of quantity of the mediating elements. As that quantity may vary, IES becomes not a single status but a gradation, and hence so does the DES/IES distinction itself. Moreover, while the link between theoretical symmetries and the world is mediated in the case of IES, the link between theoretical conservation laws and the world is not mediated. Therefore, theoretical conservation laws have DES.

In the talk I spell this out in a more nuanced way.