When I first was asked questions about morality, I didn't really think it required an explanation. What was right was right, what was wrong was wrong, and that's as far as anyone needed to go. Of course when trying that out on others it doesn't really go so well. If they have a different conception of right and wrong, then it's not just a matter of right conduct. It's having to justify right and wrong and that seeks some sort of explanation.
The context I was arguing in was one of education, that individuals knew right and wrong because that's what they were educated to believe. In that sense, I saw morality much the same way I saw law. Only that law was an explicit construct while morality implicit. This kind of explanation made sense to me as different cultures around the world had different conducts of behaviour. As the saying goes "when in Rome..."
This explanation was further solidified when I did ethics at university. Subjectivism had to be wrong because it made the conception useless. If I took your ice cream because that were permissible in my morality, it would make the action right even if you felt it wrong. So there had to be something that would transcend the individual, and it was something that wasn't absolute. So that attribution of an implicit code of conduct was something that sounded right and to my mind could explain differences.
However, I had made the same mistake as those who say altruism is for the good of the species. In seeking a crane, I had inadvertently put in a skyhook.
There were a number of problems with the logic. First was going from IS to OUGHT, that one OUGHT to follow the conventions of a society because it IS how that society operates. There's nothing to suggest that just because that's how a society does it that it makes it right.
The second problem was defining just how a group decides upon that morality. A majority of people? The leadership? The dogma that is proclaimed to be the moral fabric of the community? There's no way to solidify the concept at all.
The third problem was how these change. If morals really were culturally defined, then there has to be some mechanism by which they change. Is something immoral until it becomes the norm? Again this seems to make intuitive sense, like smoking while pregnant is something as a society is now deemed immoral where before there were no problems, but again this at best describes as IS rather than an OUGHT.
That was probably the biggest problem with my conception, there was no OUGHT, only an IS. This was back to moral subjectivism, only as the culture as the individual. It is easy to excuse Thomas Jefferson for owning slaves because that was standard in his time, but if I did that then in what sense did I have to condemn what happened in Nazi Germany?
So for a number of reasons I simply find my old view untenable to hold. It was wrong, both logically and empirically, and worst of all it wasn't useful. It put me into a spot of hypocrisy, on the one hand refusing to condemn or praise on the grounds of culture yet holding some values as beyond it. For a while I referred to my position as moral pluralism, but I was so obsessed with finding an explanation that described how we do behave than how we OUGHT to behave that the position I advocated was inconsistent.
I'm not sure whether or not I have any clearer understanding now, but I'll elaborate on where I currently sometime in the not-too-distant future.