Constraints and divergent assessments of fertility in non-empirical physics in the history of the string theory controversy

Abstract

This paper examines historic appraisals of string theory to develop a less abstract understanding of the string theory controversy and assessment in non-empirical physics. This historical approach reveals several points of conflict in the controversy, each centring on a constraint. By proceeding stepwise through these constraints, I reveal the role that constraints played in determining divergent assessments of string theory. Rather than disagreement between two competing methods, a level of agreement is found amongst those critical and supportive of string theory as to the commitment to the relevant constraints, but disagreement as to the sufficiency of consistency, the path to background independence and a non-perturbative formulation, and how to interpret the significance of applications. Furthermore, the string theory community itself is shown to be divided in its commitment to the necessity of uniqueness and the legitimacy of anthropic reasoning. These varied assessments, guided by considerations of constraints, have informed divergent claims as to the past and future fertility of string theory. These are claims as to the value of string theory in guiding research in quantum gravity: claims as to whether string theory has and will be valuable as a means rather than an end.