I don't know if this is something that the USA has been late to pick up on (a bit retarded, you could say) but retard has been pretty offensive in the UK for some time now. In much the same way that spastic was a term of playground abuse until we were all told off for using it, retard has always been a bit contentious. For example, I'd find it pretty hard to imagine a disability rights group in the UK calling itself the Association for Retarded Citizens. But then again, the expression spaz also hit the headlines a while ago in the USA, a good two decades after a school assembly from my old headteacher reminded us all that it was a bad word.
In his article, Fairman makes some very good points about the cycles words go through and the euphemism treadmill that turns to generate new terms which - for a short time at least - avoid offence to different groups of people:
The irony is that the use of "mental retardation" and its variants was originally an attempt to convey greater dignity and respect than previous labels had. While the verb "retard" -- meaning to delay or hinder -- has roots in the 15th century, its use in reference to mental development didn't occur until the late 19th and early 20th centuries, when medical texts began to describe children with "retarded mental development," "retarded children" and "mentally retarded patients." By the 1960s, "mental retardation" became the preferred medical term, gradually replacing previous diagnostic standards such as "idiot," "imbecile" and "moron" -- terms that had come to carry pejorative connotations.
What's also interesting is the parallel Fairman draws with other potentially offensive words such as the n-word, queer and gay. And while Fairman is sensitive to retard's offensiveness, his point is that we are grown up enough to show discretion and judgement in how we choose to use terms:
The current public awareness campaign surrounding the use of the word "gay" offers better lessons and parallels for the R-word debate. Advocacy groups contend that the phrase "that's so gay" fosters homophobia and that anti-gay language is directly related to violence and harassment against homosexuals. At the same time, there is recognition that much anti-gay language is uttered carelessly and isn't necessarily intended as hurtful -- as is probably the case with uses of "retard." The Ad Council and the Gay, Lesbian and Straight Education Network have developed a Web site, ThinkB4YouSpeak.com, that, much like R-Word.org, encourages the public to sign a pledge to cease using the phrase. (The slogan: "Saying that's so gay is so yesterday.")
By increasing sensitivity and awareness, the campaign hopes to encourage people to think about the possible consequences of their word choices. Such reflection would presumably lead individuals to censor themselves once they understand that others can be hurt by their language.
Inherent in this idea is the realization that words have multiple meanings and that those meanings depend on the context and circumstances surrounding any particular statement. For example, "gay" is a term of identification for homosexuals, but it also can be used as an all-purpose put-down: "That's so gay." Those using it as an insult don't intend to say "that's so homosexual," nor do they necessarily make the conscious leap that homosexuality is bad. (Indeed, the success of the ThinkB4YouSpeak.com campaign depends on this distinction.)