String theory has the potential of explaining why there are three generations of elementary particles by invoking the Euler characteristic of the compact spaces it employs

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