 Curiel goes on to question, more generally, the ranking of approaches to quantum gravity given what he views as the absence of demonstrated scientific merit in any of them: elegance and consistency might well be merits of a scientific theory, but they do not count as scientific. (ibid, p. S437). However, this claim hinges on the direct alignment of scientific merit and empirical clout; but this requires an argument, for it is far from obvious: from whence this prescription? Surely if a theory is mathematically inconsistent that says something about its physical status too? Moreover, the relationship between experimental and observational data and theories is not a simple matter. Finally, it is perhaps too quick to say that approaches do not have empirical consequences. Already known empirical data can confirm the predictions of a theory; therefore, it is clear that we can judge the extent to which the various contenders satisfy this old evidence, and how they do so. For example, string theory at least has the potential of explaining why there are three generations of elementary particles by invoking the Euler characteristic of the compact spaces it employs—the Euler characteristic is equal to twice the number of generations (see Seifert, 2004, for details). Whatever one might think about string theory’s relationship with anthropic reasoning, we do have here a potential explanation of a previously inexplicable piece of old empirical data, which ought to lend some credence to the theory. There is also the not inconsiderable fact that string theory is able to derive general relativity (and all the physically observed facts that are associated with this theory) as a low energy feature. This is not a novel fact, but it is an physical, empirical consequence of the theory nonetheless.