Reuben Hersh has argued, persuasively, that mathematics is not a collection of eternal truths existing in some ideal but nebulous world—the Platonist viewpoint—but is instead a shared human mental construct [11]. It seems difficult to maintain that mathematics is not a shared human mental construct, since it has been developed by mathematicians communicating their ideas to each other, but Platonism lingers on. The suggestion that mathematics is dependent on human conventions has proved unpopular in some circles, possibly because it appears to smack of relativism, whose more extreme form maintains that the whole of science is merely what scientists choose to believe.