 Research in quantum gravity has always had a rather peculiar flavor, owing to both the technical and conceptual difficulty of the field and the remoteness from experiment. Yoichiro Nambu (1985) wryly labels research on quantum gravity “postmodern physics” on account of its experimental remoteness. Thus conventional notions of the close relationship between theory and experiment have but a tenuous foothold, at best, in quantum gravity. However, since there is a rudimentary ‘pecking order’ amongst the various approaches to quantum gravity, and since the history of quantum gravity contains various fatalities, there clearly are some methods of theory evaluation in operation, there are constraints functioning in something like the way experiment and observation function. Investigating these methods and constraints constitutes an open research problem for philosophers of science—for initial investigations along these lines, see James Mattingly (2005a and 2009) and Rickles (2011). Audretsch (1981) argues that quantum gravity research conflicts with Kuhn’s account of scientific development since it stems from the desire to unify (for reasons not based on any empirical tension) multiple paradigms, both of which are well-confirmed and both of which make claims to universality. One might easily question Audretsch’s focus on direct empirical tensions here. Given, as he admits, both general relativity and quantum theory claim to be universal theories, any conceptual or formal tension that can be found to hold between them must point to either or both theories being in error in their claims to universality—this is an empirical claim of sorts. In the context of string theory, Peter Galison (1995) argues that mathematical constraints take the place of standard empirical constraints. James Cushing (1990) also considers some of the potential methodological implications of string theory (though he deals with string theory in its earliest days, when it underwent a transition from the dual resonance model of hadrons into a theory of quantum gravity). Dawid (2014) focuses in more detail on methodological issues in string theory and defends the idea that string theory is characterised by a uniqueness claim (the no-alternatives argument) according to which string theory is the only way to unify gravity and the other fundamental interactions, thus grounding physicists’ strong belief in the theory; however, that is a rather different problem (that of constructing a theory of everything) than the more restricted problem of quantum gravity — quantum gravity researchers from other approaches might simply reject the need for such a unified theory (e.g., as opposed to a theory that is compatible with the inclusion other interactions). 