Full Idea
If mathematical statements are part of every competing hypothesis, then no matter which hypothesis comes out best in the light of observations, they will be part of the best hypothesis. They are not tested, but are a background assumption.
Gist of Idea
All scientific tests will verify mathematics, so it is a background, not something being tested
Source
Elliott Sober (Mathematics and Indispensibility [1993], 45), quoted by Charles Chihara - A Structural Account of Mathematics
Book Reference
Chihara,Charles: 'A Structural Account of Mathematics' [OUP 2004], p.128
A Reaction
This is a very nice objection to the Quine-Putnam thesis that mathematics is confirmed by the ongoing successes of science.