A common response (although, one I cannot find an example of via the search feature, blah) I have observed from Less Wrongers to the challenge of interpersonal utility comparison is the claim that "we do it all the time". I take this to mean that when we make decisions we often consider the preferences of our friends and family (and sometimes strangers or enemies) and that whatever is going on in our minds when we do this approximates interpersonal utility calculations (in some objective sense). This, to me, seems like legerdemain for basically this reason:
One stand restoring to utilitarianism its role of judging policy, is that interpersonal comparisons are obviously possible since we are making them all the time. Only if we denied "other minds" could we rule out comparisons between them. Everyday linguistic usage proves the logical legitimacy of such statements as "A is happier than B" (level-comparison) and, at a pinch, presumably also "A is happier than B but by less than B is happier than C" (difference-comparison). A degree of freedom is, however, left to interpretation, which vitiates this approach. For these everyday statements can, for all their form tells us, just as well be about facts (A is taller than B) as about opinions, tastes or both (A is more handsome than B). If the latter, it is no use linguistic usage telling us that interpersonal comparisons are "possible" (they do not grate on the ear), because they are not the comparisons utilitarianism needs to provide "scientific" support for policies. An equally crucial ambiguity surrounds the piece of linguistic testimony that tends to be invoked in direct support of redistributive policies: "a dollar makes more difference to B than to A." If the statement means that the incremental utility of a dollar to B is greater than it is to A, well and good. We have successfully compared amounts of utilities of two persons. If it means that a dollar affects B's utility more than A's, we have merely compared the relative change in B's utility ("it has been vastly augmented") and in A's ("it has not changed all that much"), without having said anything about B's utility-change being absolutely greater or smaller than A's (i.e. without demonstrating that the utilities of two persons are commensurate, capable of being expressed in terms of some common homogeneous "social" utility).
-Anthony de Jasay, The State
I think the point is to suggest that there may be a precise concept hiding in there somewhere.
Compare with "niceness". We say "Jim is nicer than Joe, but not as nice as James", and yet there's currently no prospect of a canonical unit of niceness. There are then two things we can say:
I figure morality as a topic is popular enough and important enough and related-to-rationality enough to deserve its own thread.
Questions, comments, rants, links, whatever are all welcome. If you're like me you've probably been aching to share your ten paragraph take on meta-ethics or whatever for about three uncountable eons now. Here's your chance.
I recommend reading Wikipedia's article on meta-ethics before jumping into the fray, if only to get familiar with the standard terminology. The standard terminology is often abused. This makes some people sad. Please don't make those people sad.