Ashlanders don't seem to bother - they put the theory that appears when you call a race inferior into practice, and see Argonians, Khajiit, and others as so inferior to them that they wouldn't be able to understand instructions.
They don't necessarily object to slavery, though. I'd wager that those rights they claim to raid other tribes and settlements includes the right to take slaves, and they'd defend that right through tradition as the settled peoples defend theirs through the Armistice.
No, the ancient Chimeri morals, which now have the strength of law. I suppose that their philosophy is based on that of farmers and herders who turned away from the Aldmeri gods and to the Daedra, possibly for better protection or just a personal connection, which is, in turn, based on the philosophy of three very different Daedra.