Full Idea
The style of nominalism which aims to reduce statements about numbers to statements about their applications does not work for the natural numbers, because they have many applications, and it is arbitrary to choose just one of them.
Gist of Idea
Nominalism as based on application of numbers is no good, because there are too many applications
Source
David Bostock (Philosophy of Mathematics [2009], 9.B.5.iii)
Book Reference
Bostock,David: 'Philosophy of Mathematics: An Introduction' [Wiley-Blackwell 2009], p.301