 In earlier research on quantum gravity it was often supposed that if there was at least one quantum field in the world together with the gravitational field, then given the universal coupling of the gravitational field, it must follow that the quantization of the one field somehow infects the gravitational field, implying that it must necessarily have quantum properties too. The arguments basically involve the consideration of a mass prepared in a superposition of position eigenstates. If the gravitational field remained classical (and, therefore, not constrained by the uncertainty relations) then one could violate the uncertainty relations by simply making measurements of the gravitational field, discovering the properties of the quantized matter to which it was coupled. However, all attempts at making this argument stick have so far failed, meaning that there is no logical necessity demanding that we quantize the gravitational field. Given that we also seemingly lack experimental reasons for quantization of the gravitational field (since we have not observed evidence of its quantum properties), several physicists (and philosophers) have questioned the programme as it stands. It is, they argue, a matter for experiment to decide, not logic. Note, however, that this does not mean that the project of quantum gravity itself rests on unsteady ground: if there are quantum fields and gravitational fields in the world, then given the nature of gravity, we need to say something about the manner in which they interact. What is being questioned is whether this means that gravity cannot itself remain fundamentally classical while interacting with quantum fields. After all, as far as all our experiments show: gravity is classical and matter is quantum. This pessimistic argument is usually traced back to Rosenfeld, though he wavered somewhat on the matter (see DeWitt and Rickles, 2011, p. 164 and p. 170, for Rosenfeld’s original arguments).