Remember that I’m an anti-moral realist trying to steelman the moral realist position. As an anti-realist, it is not surprising at all that moral reasoning changes.
A thought here: if you genuinely want to steel-man moral realism you need to look at various forms of “minimal” moral realism, which are consistent with moral subjectivism. See http://en.wikipedia.org/wiki/Moral_realism and the sub-section “Robust versus minimal moral realism”.
An example here could be a missionary confronting a New Guinea highlander just after a cannibal feast (assuming these really happened). The missionary says “Eating people in your cannibal feasts is wrong”. The highlander says “Eating people in our cannibal feasts is not wrong.” According to a minimal moral realist, one who embraces moral subjectivism, both of these may be true statements—they both correspond to moral facts—because the term “wrong” has a different meaning for the different speakers. Though their meanings clearly overlap e.g. they may both agree that eating people outside special feasts is “wrong” or that sex outside marriage is “wrong”.
Or, for an analogy, consider two normally-sighted people looking at a coloured wall. One says “The wall is orange”, the other says “The wall is not orange, it is red”. Both of these statements may be true—i.e. both correspond to colour facts—because the speakers put the boundary between orange and red in a slightly different place. They have slightly different (though overlapping) concepts of “red”.
It is very hard to refute versions of moral realism like this. You’d have to somehow show that no-one has a properly consistent concept of right and wrong, so that even within the cannibal’s own moral system he is talking self-contradictory nonsense. That’s going to be difficult.
A thought here: if you genuinely want to steel-man moral realism you need to look at various forms of “minimal” moral realism, which are consistent with moral subjectivism. See http://en.wikipedia.org/wiki/Moral_realism and the sub-section “Robust versus minimal moral realism”.
An example here could be a missionary confronting a New Guinea highlander just after a cannibal feast (assuming these really happened). The missionary says “Eating people in your cannibal feasts is wrong”. The highlander says “Eating people in our cannibal feasts is not wrong.” According to a minimal moral realist, one who embraces moral subjectivism, both of these may be true statements—they both correspond to moral facts—because the term “wrong” has a different meaning for the different speakers. Though their meanings clearly overlap e.g. they may both agree that eating people outside special feasts is “wrong” or that sex outside marriage is “wrong”.
Or, for an analogy, consider two normally-sighted people looking at a coloured wall. One says “The wall is orange”, the other says “The wall is not orange, it is red”. Both of these statements may be true—i.e. both correspond to colour facts—because the speakers put the boundary between orange and red in a slightly different place. They have slightly different (though overlapping) concepts of “red”.
It is very hard to refute versions of moral realism like this. You’d have to somehow show that no-one has a properly consistent concept of right and wrong, so that even within the cannibal’s own moral system he is talking self-contradictory nonsense. That’s going to be difficult.