  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 &amp; 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 Quine (1960). The debate here is especially interesting because although both sides are Nativist—in that both accept innate ‘numerical’ systems—there are still learning elements in play in the search for an adequate psychological account of our distinctive arithmetic competence.