This is known in politics as the Overton Window.
It's pretty applicable to what you're discussing here. Basically there are some people who can see several steps ahead or behind, and there are lots of people who can only see one or two steps forward or backwards, and anything outside that window is weird/ deviant/ dangerous.
What is REALLY interesting in this discussion is that the majority of people are unable to remember what it was like to hold an opinion (ethic) that was different to the one they hold now, it seems that as a species we are, generally speaking, pretty poor at seeing outside of our own current environment and belief set.
My opinion is that when many people talk about their ethics, they are more often than not using an ''appeal to authority type argument'' (such as in the wonderful cartoon above) for people to dispense with critical, open, difficult, living thinking and rather choose to live by a set of rules that fit that persons current belief system.
Ethics are not a stick to beat other people with, which unfortunately is what happened with Mollisons 3rd ethic.
It went from being 'Setting limits to population and consumption' to 'Fair share'
Meaning that people were able to believe that they could tell other people to give them stuff, and if those people didn't comply, then they were not being ethical.
Ethics are quiet, personal things IMO. I tend to be allergic to people who have noisy ones.