What IS good, and how do we determine it?

[Silver]

But don't you believe there are some things that ARE immoral regardless of how someone might "feel?"

For example, a jealous husband can feel that murdering his cheating wife is not immoral. But he is wrong. It IS immoral regardless of how he feels or what he thinks. The question is, where does the universal truth "murder is wrong" come from?

It would obviously be wrong via the wife's feelings at being murdered by the man whom she thought loved her above all else.  

Not to mention that killing of one's own clan in primitive times was considered wrong due to the fact that survival was of the up-most importance; thus morality was born.