When, still in opposition, Tony Blair decided to send his children to the Oratory School rather than to their local comprehensive in Islington, he was attacked for surrendering Labour Party policy to his own self-interest. He responded by saying that the criticism was just "political correctness gone mad". Almost a decade later, during the summer of 2004 when, presumably, he hoped that the dearth of hard news would mean that someone might pay attention, Michael Howard made a speech attacking the constraints 'political correctness' imposed on the police and other public officials going about their business. Indeed, should you be inclined to open any right-wing newspaper, you'll find attacks on the tyranny of 'political correctness', so much so that the perception that we're all victims of a repressive politically correct police state has filtered deep into the national consciousness.

Take, for instance, a drunken friend of mine a few years ago who was bemoaning that the bumbling Etonian jack-of-all-trades Boris Johnson had allegedly been banned from the airwaves of Radio 4 because of his plummy accent. "It's just political correctness gone mad," he slurred. "I really really hate political correctness," he went on, at some length. When I tried to point out that this embargo didn't seem to have slowed Boris down any, and that he might just have got hold of the wrong end of the stick as far as this political correctness lark was concerned, he was, alas, too pissed, or possibly 'differently sober' to reply.

Then there was the time I was invited onto Radio 4's arts programme Front Row to review the first couple of episodes of South Park, the foul-mouthed American cartoon series, which, its publicity claimed, was acting as an overdue counter to political correctness.

As far as I could tell the only politically incorrect aspect of the show, which was mostly about farting and shit, was the throwaway line "Africa? Isn't that full of black people?", so I said that political correctness must be a pretty feeble behemoth (my brother-in-law later laid into me for using the word 'behemoth' on national radio) if this garbage was seen as an attack on it, and that actually the most interesting thing about South Park was the animation technique, the same as that used to make Ivor the Engine which was, in its way, much more subversive. What I didn't know at the time was that I'd been invited onto Front Row specifically to praise South Park because I'm seen as a pretty vicious cartoonist who, presumably, is meant to enjoy this kind of thing. Mark Lawson told me a few years later that because I didn't enjoy it Front Row's producers black-listed me from the programme.

So, that's me genuinely banned from the radio for being, however tenuously, politically correct, while Boris Johnson's patrician squawks, assumed to be politically incorrect, quack out of a wireless set near you almost ceaselessly. What, you might ask, is going on?

The point about political correctness, of course, is that it's an invaluable Aunt Sally, a flimsy paper tiger for anyone to have a pop at when they can't be bothered to come up with a proper argument to back up their position. Blair used it as a knee-jerk response to avoid admitting that he's just a sell-out merchant (if, that is, he ever truly bought in), while Howard evoked the monster as a cheap rhetorical device to make cheaper political capital. Had I been in a position to produce a cartoon about that speech (I was on holiday at the time), I'd have done something along the lines of "you'd expect an attack on political correctness from an oily yid like him". Not, of course, that anyone in their right mind would have published anything like that. Irony is too open to misinterpretation for newspaper editors entirely to trust their readers to get it, but I think that putative cartoon which I never drew gets us to the heart of the issue.

Political correctness is a clumsy term for affording people different from you a modicum of courtesy. Of course, like hares in March, it seems to have an amazing propensity for going 'mad' or just being silly, but then again it's a blunt political tool wielded with entirely laudable intentions: that, in public at least, you don't glibly assume you can denigrate people merely because of their ethnicity, sexuality, physical condition or gender. So when a racist comic or a reactionary columnist or a shameless politician or a lazy policeman complain that they're straining under the unendurable yoke of political correctness (which, inevitably, has also gone mad) what they're really saying is that they've been deprived of their inalienable right to call blacks 'niggers', jews 'kikes', South Asians 'pakis', the disabled 'spazzes' and women 'whores' as a very blunt political tool to keep them in their places.

But isn't that what free speech is all about? And how can I, as a satirist, possibly endorse a constraint on abuse? Except that there is a difference between believing in anyone's right to express their opinions and guaranteeing their right to shout "Fuck off, you nigger cunt!" at Archbishop Desmond Tutu during a television interview. Or to a black suspect in a police station, for that matter. And, of course, the point of satire is to comfort the afflicted and afflict the comfortable. In other words, only attack people more powerful than you, who tend, by and large, not to be the beneficiaries of political correctness.

And we should all applaud the fact that as a political gambit 'political correctness' has proved so effective that the 'alternatively liberal', the 'differently powerless', now pretend that they're the victims instead.