There's been a spate of ableist language in my life this week (that is, language that discriminates against people with disabilities).
First, in my very modern (2011) linguistics textbook, one of the examples used the word 'Mongolism'. This word used to be used to refer to people with Down's Syndrome but has been considered offensive for some time, so we don't use it, especially not in textbooks.
Then today, a weird mismatch of expectations happened on the Today programme on Radio 4. Lynda La Plante was on, and during the course of her interview she mentioned that she had been misquoted as saying that people at the BBC were 'retards'. You could almost hear the relief in the presenter's voice when she heard it was a misquote (I presume the presenter was Sarah Montague, as she is the only female presenter listed on the website). So she asked what exactly La Plante had said, and it was here that there was a sharp divergence of what the problem is with having been quoted as calling the people at the BBC 'retards'.
It transpired that she hadn't said that they all were; she had merely said that it was possible that someone there might be a retard.
She did use the word, and she then repeated it several times on air. This was not at all what the presenter had been hoping for when she sought to clarify La Plante's actual words and you could almost hear the producer yelling 'Move on! Stop her saying that word!' as she scrambled for a different topic.
What a difference! La Plante thought that the problem with being misquoted was that she had cast a slur on all BBC employees, whereas the problem for just about everyone else in the world is that the word 'retard' is actually highly offensive to a lot of people and it's just best not to use it if you want to be at all sensitive to people's feelings.
This word wasn't always taboo - it used to be the standard way to refer to someone with a learning disability. And of course the verb itself is not offensive - a chemical reaction could be retarded at lower temperatures, for instance. It just means 'slowed down'. In fact, 'mental retardation' is still used as a medical term for particular conditions. 'Retard', however, is not acceptable, and at this year's Olympics there was a bit of a hoo-haa when some idiot used it to describe Obama.
But derogatory terms move in a cycle. As a medical term gains broader use, it becomes derogatory. 'Imbecile' used to be the term for a particular mental disability, as did 'cretin', 'idiot' and so on. If you use the term for a person with a mental disability as an insult, you imbue that term with derogatory meaning, because you're saying that it's bad to be an imbecile, and idiot or a cretin. (Consider also the criticism of the use of 'gay' to mean 'stupid'.) Note that today, no one objects to the use of these words from a PC point of view (though they might not like to be called them). 'The r-word', on the other hand, is still very much within this process. Unfortunately for the Today programme, no one told La Plante.