A few weeks ago, I was at a dinner party where I found myself defending MTV's new reality show, Rich Girls. This show is the apex of shallow, chronicling in painstaking detail the lavish shopping sprees of Ally Hilfiger (daughter of Tommy) and her friend Jaime Gleicher. My friend argued that although shows such as Pop Idol and The Simple Life were, admittedly, dumb, they still maintained a kernel of value (Pop Idol requires a talent; The Simple Life, featuring the It girl Paris Hilton living on a farm, has as its premise "fish out of water learns how to cope"). A show like Rich Girls, she said, was about nothing more than shopping.

Precisely. It is a show with no redeeming social value whatsoever. There is no pretence. And therein lies its beauty.

A rash of stupid entertainment has recently invaded our radar - from The Osbournes to Johnny "Jackass" Knoxville, not forgetting the daily exploits of the fabulous Britney Spears. It's not just that Britney does stupid things (who hasn't got married as a "joke"?), it's that she doesn't seem all that bothered about her simple- mindedness. She recently confessed to never having heard of John Lennon.

Initially, I thought she meant she hadn't heard him sing, which was bad enough, but I soon discovered that no, she'd really never heard of him. Her excuse? He was before her time. Hmm. So was Jesus Christ - has she heard of him? It's a good thing she's cute.

And therein lies the nub of it: stupid has become kind of glamorous. The Hilton sisters - Paris and Nikki - may be idiots, but they have become bewitching, iconic idiots. In The Simple Life, Paris and her best friend, Nicole Richie (Lionel's daughter), are sent to live with a family in the Ozarks, Arkansas. Landing on a farm as if they have landed on the moon, they bring Louis Vuitton luggage and Tinkerbell, a chihuahua in Chanel booties. The new stupid have style.

Yet what is intriguing is that while the Hilton sisters are vilified for doing nothing, they have created a template for success that captures Andy Warhol's prophetic American dream: free fame. But then, Americans have always embraced stupidity. In movies and in television, it is a useful comic device - think Joey from Friends, or the hugely successful Dumb and Dumber, or Clueless, which started the whole genre off. It's usually offset by something that keeps us from feeling sorry for the person - good looks, salaciousness, oversized ego, luck with the ladies - but in these new reality shows, the stupidity is even funnier because, really, you couldn't make it up. You can't believe someone could actually say something so ridiculous and that it's not a line crafted by a bunch of comedy writers sitting round a table.

In Rich Girls, Jaime thinks she's much smarter than she is. She's a "novelist".

But when she tries to use big words, they backfire on her. So when she feels left out, she says: "I just feel really secluded", instead of "excluded". And she and Ally sit around philosophising about class differences, and the politics of cargo pants. They think they have tremendous insight when they arrive at the conclusion that someone in the Midwest wears cargo pants not because they would look great with strappy heels and a cute tank top, but because they need the extra pockets when they're working in the fields.

One episode of Rich Girls features Ally alone at her father's mansion in Connecticut. It opens with her dangling her legs into the pool and crying into her mobile phone to her dad that she "never had a childhood". After a few minutes, the conversation is cut short when Ally has a sudden burst of independence. She's going to make a sandwich. Entirely on her own.

The problem is, she has no idea what actually goes into a sandwich, so the rest of the show revolves around her valiant attempt to prove to herself she can make it happen. We see Ally at the supermarket, dazed in the cheese section, not knowing what to buy. In the produce department, we see her pondering over lettuce, and whether or not she actually needs it. In the end, she is in the kitchen, chopping and slicing - but it's still not working out and she has an emotional meltdown. Unable to understand why she is in floods of tears, she cries out: "I just want to make a sandwich."

Despite the absurdity, or maybe because of it, there is something that we can relate to Ally's struggle. When everything in life feels as if it sucks, you just want one simple thing to work out - it's only a matter of degrees.

What Rich Girls does is take all of the emotional complexities of life and distil them down to moonshine. We relate to the frustration, the anguish, the existential despair of not getting what we want. What gives the show levity is that there is total guilelessness about Ally and her friends as they shop their way over a threshold into adulthood.

So while we learn how to earn a living, Ally learns how to make a sandwich. We empathise with Ally and Jaime's stupidity in a "there but for the grace of God go I" sort of way.

With Paris Hilton, it's a different story. Her stupidity delights us because we see that no, she doesn't have everything. She can enter a lawn party by customised helicopter, but she probably has no idea what the metro is. You would think all her wealth and privilege and travel and exposure to the world would make her worldly, but it doesn't: she's still unbelievably ignorant. "What's Wal-Mart?" she asks. "Is that where they sell stuff for walls?" When we see photos of her, we feel deprived because she lives a life we never could - but when we see her being an idiot, we get to feel superior. (If I were Paris's sister, Nikki, I'd be dancing for joy. Compared to Paris, she comes off looking like Madeleine Albright.)

It's not just Americans who glamorise idiocy, though. Jordan? Jade from Big Brother? These women have been profiled by intellectual magazines and embraced by the middle classes. Or how about Ozzy Osbourne, the man who did so much acid that his brain is a doily, but who has become a national treasure? So much so that the Prince of Wales, hearing about Ozzy's recent accident, sent him a bottle of scotch as a get-well offering. Great gift, except for one thing. Ozzy's whole image is now that of a recovering alcoholic. Now that's brilliantly - Britishly - stupid.