Well, again, you're kind of just asserting your claim. Prima facie, it seems pretty plausible that whatever function evaluates how well off a person is could take into account things outside of their mental states. People looking after their families isn't often thought of as especially altruistic, because it's something that usually matters very deeply to the person, even bracketing morality.
Your second paragraph is genuinely circular: the whole argument was about whether it showed that S was false, but you appeal to the fact that
whether the cube exists in this example is completely decoupled from whether P believes the cube exists
This is only relevant if we already think S is true. You can't use it to support that very argument!
Look, if it helps, you can define utility*, which is utility that doesn't depend on anything outside the mental state of the agent, as opposed to utility**, which does. Then you can get frustrated at all these silly people who seem to mistakenly think they want to maximize their utility** instead of their utility*. Or just perhaps they actually do know what they want? Utility* is a perfectly fine concept, it's just not one that is acutally much use in relation to human decision-making.
Edit: remember to escape * s!
Edit2: quoting fail.
Look, if it helps, you can define utility*, which is utility that doesn't depend on anything outside the mental state of the agent, as opposed to utility**, which does. Then you can get frustrated at all these silly people who seem to mistakenly think they want to maximize their utility** instead of their utility*.
Someone can want to maximize utility**, and this is not necessarily irrational, but if they do this the are choosing to maximize something other than their own well-being.
Perhaps they are being altruistic and trying to improve someone else's ...
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.