Indispensability, the Testing of Mathematical Theories, and Provisional Realism

Mathematical concepts are explications, in Carnap's sense, of vague or otherwise unclear concepts; mathematical theories have an empirical and a deductive component. From this perspective, I argue that the empirical component of a mathematical theory may be tested together with the fruitfulness of its explications. Using these ideas, I furthermore give an argument for mathematical realism, based on the indispensability argument combined with a weakened version of confirmational holism