I never said that structures of this sort are arbitrary. I can see why you interpreted my comments on the N-word that way, but what I said was that the word got it's offensiveness from the history of it's use, not by arbitrary fiat. As I said "It acquired its vileness from who said it for hundreds of years, and how they were treating African-Americans when they said it." The word is not intrinsically insulting, like the word "untouchable" for India's lower caste Dalits. But this history of use is a real set of events, not a made-up line.