  That strategy has been pursued by Richard Boyd in defense of his naturalist form of moral realism, which is sometimes referred to as “new wave moral realism” (Boyd 1988, but see also Brink 1989). Boyd appeals to a causal theory of reference. His version of that approach is complex and differs in significant ways from more familiar versions (such as those offered in Putnam 1972 and Kripke 1980). But the main idea is that moral terms refer to the properties that “causally regulate” our uses of those terms, including our dispositions to apply them in particular cases. Such regulation presupposes that there are mechanisms which causally connect (instantiations of) the properties with the uses. Boyd insists that those mechanisms must ensure some tendency to apply the term reliably to actions, persons or states of affairs which have the properties in question, to secure a degree of epistemic access to them. However, he also stresses that this constraint does not preclude serious errors. Our use of “good” can be relevantly regulated by a certain property even if we are ignorant of it and even if our ignorance results in many affirmations which are false (given that the term refers to the property in question). Differences in our use of moral terms and sentences of the kind that Hare highlighted are therefore consistent with co-reference and accordingly also with thinking that there is a shared (factual) subject matter over which the people in his scenario express conflicting beliefs by using the pertinent terms and sentences.