Full Idea
Abstract entities are useful because we can use them to formulate abstract counterparts of concrete statements.
Gist of Idea
Abstractions can form useful counterparts to concrete statements
Source
Hartry Field (Science without Numbers [1980], 3)
Book Reference
Field,Hartry: 'Science without Number' [Blackwell 1980], p.24
A Reaction
He defends the abstract statements as short cuts. If the concrete statements were 'true', then it seems likely that the abstract counterparts will also be true, which is not what fictionalism claims.