Superficially, at least, it seems as if Wittgenstein is offering an essentialist argument for the conclusion that real number arithmetic should not be extended in such-and-such a way. Such an essentialist account of real and irrational numbers seems to conflict with the actual freedom mathematicians have to extend and invent, with Wittgenstein’s intermediate claim (PG 334) that “[f]or [him] one calculus is as good as another”, and with Wittgenstein’s acceptance of complex and imaginary numbers.