Well, yeah. I'm not offended by the C in NAACP -- which isn't racist for obvious reasons -- but someone out there must be. That's not an argument for changing the name. I am offended, however, that the Philadelphia Eagles are named after the Blue Eagle, the propaganda symbol of the New Deal's National Recovery Administration, which restricted competition and even threw a dry cleaner in jail for undercharging (by a nickel) to clean a suit. But I don't think the Eagles should change their name on my account.
And that's my problem with Costas' crusade. He -- and the editors of Slate -- are simply deciding to be offended about something they don't need to be. According to various accounts, "Redskin" actually has quite innocuous origins. It was probably adopted from Native Americans themselves. And though it obviously took on nastier connotations over time and in some contexts, it strains credulity to believe that the team name was intentionally pejorative or that the fans or the ownership see it that way today.
Words become offensive when we choose to be offended by them. When should we be offended? That's a tough question. "The answer, of course, lies in the context," the late Hugh Rawson wrote in his lovely lexicon, "Wicked Words." "The meanings of words change according to who says them, to whom, and in what circumstances." Rawson chronicled many words that were uncontroversial in Chaucer and Shakespeare but are considered repellent today.
Ultimately, of course, this isn't a fight about words but about cultural politics and the imperative to scrub society of all offensive language (or, often, merely language that offends liberals). That fight will never end, and not just because some people always need to be offended by something. It will never end because words themselves will never cooperate.