Until we have settled the question of whether moral beliefs necessarily have motivational force, for example, we are in no position to say whether it is a point in favor of a given account of our moral practice that it endows them with such a force; and until we have decided whether mathematical beliefs can be known a priori, we will be unable to say whether it is a point in favor of an account of our mathematical practice that it allows them to have such a status. A realist or antirealist conclusion therefore represents the terminus of philosophical inquiry into a given area rather than its starting point; and so it is hardly surprising that such slight progress has been made within realist metaphysics, even by comparison with other branches of philosophy.
Kit Fine, ‘The Question of Realism’, Philosophers’ Imprint, vol. 1, no. 1 (June, 2001), p. 25