Much of the discussion about ethics revolves around an analogy to matters of personal preference. doctor(logic) recently said,
Morality bears all the hallmarks of something subjective, like taste in food or taste in art.
My argument is that, unlike the objective sciences, morality has no more basis for objectivity than the things we regard as subjective (food, music, etc). In particular, there is no formal evidence that moral opinions are objective facts because the only thing predicted by morality is how members of our species feel about certain acts.
It seems to me that this analogy fails right where it counts most. I like chocolate and I dislike Brussels sprouts. I do not therefore conclude that chocolate is right and Brussels sprouts are wrong, or that eating one is right and the other wrong. It’s a completely different internal apprehension for these things than it is for murder or torturing children, or for loving and giving.
Morality predicts more than “how members of our species feel.” It predicts persons’ convictions and beliefs; and yes, we can tell the difference between feelings and convictions. The moral sense is not just one of personal liking or appreciation. It carries with it an incorrigible sense of rightness vs. wrongness. We do say that murder is wrong and that being a loving person is right, and most of us, when we say these things, believe they are actually true statements, not mere expressions of preference.
Granted there is some analogy between gastronomic or aesthetic taste and moral beliefs. The moral subjectivist can rightly say that the moral sense is another instance of personal preference or aversion, just as matters of taste are. We all say things like “I like chocolate,” and “I like it when people get along well.”
But when he says it is just another instance of personal preference or aversion he goes beyond what this analogy can support. We say things like “Murder is wrong,” but we do not say things like “Brussels sprouts are wrong.” But this is precisely the question of moral realism: whether statements like “murder is wrong” are really true. Any thoughtful person would say that “Brussels sprouts are wrong” is not a true statement. Only someone whose metaphysical views have successfully overridden his native knowledge would deny that “murder is wrong” is a true statement.
The analogy between morality and matters of taste fails at the point where we speak of something’s being actually true. And that’s exactly the point that matters.