For these reasons, some have argued that aside from these well-evidenced systems, there must be a third element in the human mind—viz., an innate concept of number, which must involve the grasp of a fully-general successor function—that grounds adult mathematical competence (see Leslie, Gallistel & Gelman 2007, for example). Others, like Carey (2009) have argued that the concept of exact number is not innate, but is constructed by the kind of language-based bootstrapping sketched out by Quin