 We saw above that the representation of mathematical objects in traditional set theory (proceeding “bottom up”) brings with it the possibility to express all sorts of properties about their set-theoretical constitution that are not isomorphism invariant in this sense. The central advantage of category theory over classical set theory (and similar approaches) is, according to this argument, that such non-structural properties are simply ruled out in the categorical framework. This point was first stressed in McLarty’s “Numbers Can Be Just What They Have To” (1993), which, as the title suggests, presents a rejoinder to Benacerraf (1965). McLarty’s central thesis in this article is that Benacerraf’s structuralist program is most successfully realized if one considers numbers to be represented in categorical set theory (such as in ETCS or a subsystem thereof), and not in orthodox set theory. 