Is it now okay to call Goody subhuman?

Stupidity is less common than people think. Mostly, what we mean by stupidity is a form of intelligence that is different from the approved norm or from the particular set of mental skills that we ourselves possess. David Beckham would probably not be the best person to talk to about Proust or astrophysics.

But he can do something astonishingly intelligent: calculate, intuitively and almost instantly, the precise alignment of physical forces necessary to send a football on a curving trajectory around the bodies of other players and into the goal. Conversely, the architects of the Iraq war - Donald Rumsfeld, Paul Wolfowitz, Douglas Feith, Richard Perle, Condoleezza Rice - are among the best-educated, most articulate and most intellectually accomplished holders of public office in recent times. And they conceived and implemented one of the stupidest plans of the last century.

People are seldom stupid, but their words and actions often are. Most of us are stupid in some respects, smart in others. And because we know this, we tend to be deeply insecure about our own intelligence. We need reassurance, and we get it by labelling other people as stupid.

Any teacher will tell you that a child who is having trouble with a subject in class will reach for the ultimate weapon: "That's stupid." This mechanism now operates on a grand scale. In society as a whole, we increasingly organise and justify hierarchies by pretending that the rich are rich because they're smart and the poor are poor because they're stupid. What we've seen in the whole Big Brother melodrama over the last week is how deep this assumption goes.

The new form of celebrity that has emerged from sport (especially soccer) and reality TV shows is disturbing because it confuses the distinction between rich and smart on the one side and poor and stupid on the other. The standard explanation for the hatred that someone like Jade Goody evokes is that she has become rich and famous without having any talent whatsoever. But this is hard to credit, especially in a society like Britain which places at its apex a royal family whose wealth and glamour is entirely unrelated to any kind of talent. Manufactured celebrity merely confers on someone like Goody a little of the money and the status that hundreds of thousands of people in our societies acquire through inheritance.

What really sparks the outrage is not the spectacle of undeserved wealth but the fact that it is conferred on the undeserving poor. The way to deal with this disturbance is to reach for the old reliable - stupidity. A Jade Goody may, alas, escape poverty but, we reassure ourselves, she will always be stupid.

The irony is that if you want to see stupidity in action, you need look no further than much of the self-righteous reaction to the undoubtedly racist bullying in the Big Brother house. Racism is vile because it treats people, not on their merits, but as members of a category to which subhuman characteristics have already been assigned. But in condemning Goody and her little gang of bullies, much respectable opinion resorted to precisely the same mechanism.

On the BBC's Question Time, the former Tory minister Edwina Currie called Goody and the two young women who were her companions "slags". The audience applauded enthusiastically.

This kind of language - "slags", "scum", "chavs", "povvos" - is threaded through the whole debate, often used by people who claim to be outraged that Goody called Shilpa Shetty "Shilpa Poppadom".

And it is not just an intemperate but understandable reaction to the on-screen bullying. Goody in particular attracted the most vile, fascistic ranting long before the whole Shilpa episode. The online Urban Dictionary, a respectable, user-created dictionary of contemporary slang, defines "Jade Goody" as: "A horrific abomination of a human being. Became famous for being as thick as, and uglier than, pigshit after appearing on Big Brother".

And the definition gets much worse.

After last week, the new social etiquette seems to be that racism is not acceptable but you can call uneducated, white, working-class people anything you like.

It is now okay to regard the urban underclass as a kind of genetic sludge-tank, occupied by a subhuman race with no capacity for intelligent life. There is nothing new in this: the Irish as a whole once belonged to this category. The eugenics movement, promoted by intelligent, cultivated people, proposed the sterilisation of the lower orders to stop them passing on their defective genes.

Condemning people for their supposedly ineradicable stupidity is easier, after all, than tackling the long-term structures of inequality and deprivation that create and sustain an underclass. And it's easier, it seems, to meet one kind of stupidity with another than to think intelligently about our societies.