According to structuralism in the philosophy of mathematics, the natural numbers are individuated purely by their structural interrelations. A related metasemantic view, which I call axiomism, holds that the meanings of our arithmetical terms are determined just by our acceptance of categorical axioms for arithmetic. Against both structuralism and axiomism, I present the case of the Dyadians. These speakers accept principles identical to our Peano axioms. Nevertheless, it seems clear that they u…
Read moreAccording to structuralism in the philosophy of mathematics, the natural numbers are individuated purely by their structural interrelations. A related metasemantic view, which I call axiomism, holds that the meanings of our arithmetical terms are determined just by our acceptance of categorical axioms for arithmetic. Against both structuralism and axiomism, I present the case of the Dyadians. These speakers accept principles identical to our Peano axioms. Nevertheless, it seems clear that they use terms like “13” and “natural number” with different meanings from us. English speakers and Dyadians refer to numerical structures that are isomorphic but distinct, a possibility that axiomists and structuralists cannot adequately account for. This basic problem has been noted before, going back all the way to Russell’s Principles of Mathematics (1903), but it has often been brushed off. My primary aim in this paper is to clarify the costs of doing so. In the final section of the paper, I suggest a remedy. Contra structuralism and axiomism, we should acknowledge that the natural numbers, and the meanings of our basic arithmetical terms, are essentially tied to counting. This is also reminiscent of proposals from Russell, Frege, and the neo-Fregeans. However, I identify two senses of the transitive verb “to count” that are often conflated in this context. In only one of the two senses is counting essential to the natural numbers or our concepts of them.