In many areas of dispute between realism and antirealism, realism is the natural metaphysical position. We begin as realists about the external world or the unobservable entities mentioned in well-confirmed scientific theories. Generally, peoplebecome antirealists about these things (if they do) because they become convinced that realism is in some way naive and must be abandoned in the face of compelling metaphysical and epistemological objections. So too, I think, in ethics. We begin as (tacit) cognitivists and realists about ethics. Moral claims make assertions, which can be true or false; some people are morally more perceptive than others; and people’s moral views have not only changed over time but have improved in many cases (e.g., as regard slavery). We areled to some form of antirealism (if we are) only because we come to regard the moral realist’s commitments as untenable, say, because of the apparently occult nature of moral facts or because of the apparent lack of a well developed methodology in ethics.

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 knowna 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.

Naive realism leads to physics, and physics, if true, shows that naive realism is false. Therefore, naive realism, if true, is false; therefore it is false.