Non-empirical robustness arguments in quantum gravity

In the first part of the article, I illustrate and assess instances of non-empirical robustness analysis as they occur within and across different theories of quantum gravity. The endeavour is expected to offer insights into the actual role robustness analysis plays in non-empirical theory development where motivation and theory development are not reactions to straightforward empirical problems.

In the second part, I aim at making mileage in providing a web of principles for quantum gravity research — a systematic ordering and assessment of principles for quantum gravity research in terms of a graph structure as originally proposed by Crowther and Linnemann (2017): To achieve this, I first draw on the results of the presented case studies to identify theory-overarching relations between principles which can feature in the web. I then assess the epistemic power of the thus obtained web and its prospects as an aid in the context of discovery more generally. This part is hoped to be helpful to the working physicist actually pursuing a theory of quantum gravity — by providing both an overview on how specific principles relate to one another and a methodology of how to reliably relate them in the first place. This is not to say that this aspect is not of interest to the philosopher — especially the (normative) task of providing a methodology raises relevant questions on how to distinguish between what's pursuit-worthy, and what's not.