 Field’s physicalist interpretation of arithmetic and analysis not only undermines the Quine-Putnam indispensability argument. It also partially provides an answer to Benacerraf’s epistemological challenge. Admittedly it is not a simple task to give an account of how humans obtain knowledge of spacetime regions. But at least according to many (but not all) philosophers spacetime regions are physically real. So we are no longer required to explicate how flesh and blood mathematicians stand in contact with non-physical entities. But Benacerraf’s identification problem remains. One may wonder why one spacetime point or region rather than another plays the role of the number \(\pi\), for instance.