"Nigger." You know the second you hear it that the person saying it is a bigot, an ignorant white racist, head full of prejudices and probably a card-carrying member of some far-right political group with a fondness for Nazi memorabilia.
But when you hear someone use the word "gay" instead of homosexual or a more obviously scornful epithet, you register a different image. The speaker is of liberal persuasion, probably aware of social decorum, attentive to others' sensibilities and mindful of the susceptibility of minority groups to stereotypes and labels.
Different words tell us different things about their users. We can form social categories based on the language we hear used in relation to all manner of groups, including ethnic minorities and people of various sexual propensities. Unless the user happens to be one of the following: a hip-hop artist or a Radio 1 DJ.
This week we've heard David Cameron sermonising on the evils of rap music, a genre that deliberately resists and subverts the protocols of contemporary language and uses terms that would instantly draw accusations of racism were they uttered by anybody but a rapper.
We've also heard BBC Radio 1's Chris Moyles using the word gay in a derogatory though not intentionally homophobic way, according to the BBC, which refused to uphold a complaint from Stonewall, the gay rights group. Explaining its decision, the BBC drew attention to the context in which the word was used, pointing out that gay was widely used by young people to mean "rubbish".
It might have used a similar contextual explanation to defend its inclusion of hip-hop music, particularly in the Saturday night show singled out by Cameron as glorifying "guns and violence". It is not, said Cameron, demonstrating his mastery of today's idiom, "cool".
Are white, heterosexual males pushing the reset button? Cameron's censorious pontificating and Moyles's self-authorised expropriation are signs that white men are seizing their historical privileges back. They want to be arbiters of language again - as they were a few decades back.
In the 1980s, young blacks rioted and were seen as unruly manifestations of a cultural difference that threatened stability. Since then we have learned, sometimes painfully, to embrace the same difference we once feared. A crucial part of the project centred on language.
Using words like "queer" or "bent" was hardly likely to promote the belief that there was no absolute and unconditional standard of normality. Quite the opposite: those who deviated from the standard were reckoned to be so marginal that the nouns chosen to describe them either secreted or made evident contempt and prejudice. And so it was with "wog", "coon", "paki" and the other derisive and deliberately hurtful terms used quite casually in reference to ethnic minorities.
Leaving aside the excesses of political correctness ("Baa baa black sheep"; "manhole cover"), it was effective in exposing the falsity of "sticks and stones...". Names were potent weapons. But, if the words we spoke played such a powerful role in perpetuating our prejudices, then changing them would help to defy those prejudices.
The BBC, along with other television networks, cleared out dodgy language, even if it was spoken in inverted commas, such as in sitcoms and dramas.
For all the complaints about political correctness, the tendency reminded us that the words we use are connected to the thoughts we harbour. Ideas don't form in the mind independently of the language we use to express them. Language is an instrument, though not a neutral one: it inclines us to think in some ways rather than others.
Against a background of proliferating cultural diversity, we created an imaginary nation, one in which we welcomed difference rather than tried to eliminate, repress or incorporate it. There was woe for anyone caught uttering words that in some way denigrate minorities. (Even denigrate, meaning literally "blacken" became questionable.)
And then something happened: the groups intended to be the beneficiaries of the changing lexis sensed that the respectability conferred in absentia, so to speak, concealed the persisting antipathy they experienced and disguised their presence. Their response was either ingenious or backward looking, depending on your perspective. They twirled the terms of disrespect.
"Queer" was rehabilitated, given a fresh and, in many ways, militant new connotation. "Nigger" mutated into "nigga", a term that could be used with neutrality by black people, but which remained abusive when spoken by anyone else. Jennifer Lopez, boxer Hector Camacho, both of Latin American descent, and white film director Quentin Tarantino were among those who expressed their affinity with blacks, but were criticised for saying nigga in public. Words once used to differentiate and keep out were re-coded in a way that excluded the excluders.
The 1975 edition of the Oxford English Dictionary I have had since my undergraduate days defines "Jew" as, among other things, a "person who drives hard bargains", and adds the verb "jew", which is to "cheat".
The same volume limits its definition of gay to three meanings, two relating to light-heartedness and flamboyance, the third being "dissolute, immoral; (sl.) homosexual". By the 1980s, it was respectable, by the 1990s a tad too respectable for some. And now, it might be approaching extinction.
Nigga, on the other hand, shows a survivalist instinct. Both blacks and whites alike used to describe others as "coloured" to signify their respect for them. It might have been a grudging or a superficial respect, but it was once better than the disparaging "black". When "black" was transformed in the 1970s, "coloured" seemed increasingly transparent: a perfunctory acknowledgement rather than a genuine expression of esteem. It got worse as time passed. Soon "coloured" was used only condescendingly and gauchely by those who sought to be polite but who knew little of what was really going on among black people.
While he is at pains to display his Notting Hill boho credentials, Cameron appears to be the kind of person who might use "coloured". He's no doubt been advised never to do so, of course; though his deracination of rap betrays an indifference to contemporary black culture. Moyles, being a Radio 1 jock, probably knows about these things, but couldn't care less about upsetting anyone. (His strong listener ratings have rendered him virtually untouchable.)
Neither of them seems at one with the Zeitgeist. Yet this doesn't stop Cameron - a man who numbers Benny Hill's "Ernie (The Fastest Milkman in the West)" among his favourite tracks - making prescriptive statements about popular music. Nor prohibiting Moyles's employers and, historically, the institutional foundation of sensibility from passing judgement on the (to use another word of our times) appropriateness of terminology.
For my own part, I have no objection to the Conservative leader's purveying his views on hip-hop. I'm guessing the 50 Cent and Snoop Dogg albums that any self-respecting trustafarian must own have given him some background knowledge on the genre.
I sort of resent Moyles's indiscreet way of turning gay into a slur, though I'll wager he's seen Brokeback Mountain and Capote and wasn't affronted by either. And, working in the media, he will almost certainly have friends who are gay. What I object to is the way in which their questionable dispensations have been allowed to pass unchallenged. Since when were two influential and well-paid (in Moyles's case, extravagantly well-paid) white males with, as far as we know, no sexual ambivalence in their predispositions, qualified to be arbiters on popular terminology?
The two events are symptomatic of a reassertion of long-standing rights, those of white men to pronounce on... well, anything.
We would take notice. But would we give the critics credence? Cameron has authorial weight, the gravitas that comes with the demographic profile and the political office. And they don't come much weightier than the BBC. The sources guarantee that we will take the pronouncements seriously.
The two episodes represent the comeback of the undead white male. Put another way, they disclose the limits of the liberal pluralist vision of a society based on managed cultural difference. Over the past two or three decades, we have progressively worked towards an integration of cultures and lifestyles, in which difference has been celebrated and sharedness has been enhanced. And yet we have struggled with the effects.
New Labour's vocabulary of difference and unlimited possibilities has introduced a new atmosphere. But experiences, especially since 11 September 2001, have brought home the uncertainties inherent in a society that preaches difference yet has concerns focusing on global security, identity cards, core values and, most significantly, common sense.
The returning white male is bringing a censorial mandate: minorities can be reprimanded for the incautious use of language; white men can use what minorities themselves regard as insulting language with impunity.
Politicians and major media corporations alike deal with active groups that register their identities and preferences with a variety of responses, including cynicism, suspicion, retreat and inattention. If a Tory politician either cannot or will not take some of them seriously, we shouldn't be surprised, should we? The BBC, I suspect, will continue scheduling rap.
So it's dismaying to discover that the Beeb finds the context of Moyles's show, which is flip and frequently mocking, mitigation for insulting gay people. Inevitably, there is some migration of schoolkids' terms to a radio station aimed at young people. This shouldn't implicate the BBC in mirroring and reproducing popular prejudices, as it seems to have both done and defended.
Equally, it shouldn't elide them. At the risk of loading the BBC with even more patrician responsibilities, I'll suggest it has an obligation to deflect terms that have the potential to harm. But it might go one better and challenge its DJs to consider their insinuations. Cameron, as we now know, is one such listener.
Ellis Cashmore is professor of culture, media and sport at Staffordshire University. His book 'Tyson: Nurture of the Beast' is published by Polity