 This argument appears to beg the question. Price’s objection comes to this: we know a priori that realism is an error in the case of secondary qualities, but it remains an open question whether it is an error in the case of moral properties. But the sentimentalist can maintain that, strictly speaking, the one identification is as much a metaphysical error as the other, though we make them often enough in ordinary life. It only seems to Price to be an open question in the moral case because he rejects the metaphysics of the sentimentalist.  But that is precisely what is in dispute. If moral properties are affective responses, it is incoherent to ascribe them to objects.