 The debate between strings and loops on this matter is severely hampered by the fact that there is no firm definition of background independence on the table and, therefore, the two camps are almost certainly talking past each other when discussing this issue. It seems prima facie reasonable to think that in order to reproduce a manifestly background independent theory like general relativity, a quantum theory of gravity should be background independent too, and so background independence has begun to function as a constraint on quantum gravity theories, in much the same way that renormalizability used to constrain the construction of quantum field theories. Advocates of loop quantum gravity often highlight the background independence of their theory as a virtue that it has over string theory. However, there is no proof of this implication, and aspects of the so-called ‘holographic principle’ seem to suggest that a background independent theory could be dual to a background dependent theory (see the contributions to Biquard, ed., 2005). Furthermore, depending on how we define the intuitive notion of background independence, and if ‘clues’ from the duality symmetries of M-theory are anything to go by, it looks like string theory might even be more background independent than loop quantum gravity, for the dimensionality of spacetime becomes a dynamical variable too (cf. Stelle, 2000, p. 7).