When I was growing up, I was told that I was living in a "multicultural society", which meant that people of different cultures could live alongside each other as equals. In this society, everyone was free to practise their own religion, and educate their children according to the values they believed in. Although learning English was a major advantage for getting on in life, and most people therefore did, it wasn't compulsory. Indeed, in some areas of the country, people were actively encouraged to learn and speak a different language; the general consensus being that "cultural diversity" was good for our society, and worth preserving.

The society I grew up in wasn't perfect by any means, but I quite liked it. You could, for the most part, live as you pleased, so long as you didn't infringe on other people's rights to live as they pleased. I liked the fact that my capital city was so diverse, open and integrated. I liked the fact that my country was a safe haven for people who came here fleeing persecution in less open, tolerant countries. I knew that in many other European countries, minorities didn't have the same protection from discrimination that they did in Britain, and ethnic minorities were much less integrated. I knew there were countries around the world, like Apartheid South Africa, where people of different races and cultures were not treated as equals.

I knew that in the past my country had not been so tolerant. Religious minorities had suffered persecution for hundreds of years. In the 19th Century, Welsh children were forced to speak English at school and beaten if they were caught using their own language. During the Second World War, hundreds of German Jews had been refused entry to Britain and "sent home" to their deaths. Even in the 1960s, my mother told me, you would see signs around London saying "No Jews, No Blacks, No Irish".

I knew that there were some people who pined for the days of English dominance, who bemoaned the fact that it was no longer legal to put up signs in shop windows barring certain ethnic minorities from coming in, and who wished that our country was more like Apartheid South Africa. But these people were an extremist minority, and for the most part the government had the good sense to ignore them.

As time went on, I grew to like my multicultural society more and more. I left the monocultural small town I'd grown up in, and moved to London. This big, cosmopolitan city seemed especially strong and vibrant for the fact that so many different cultures existed here side by side. Living in London was an education, and I loved having friends from all over the world; Europeans, North and South Americans, Asians and Africans; Hindus, Christians, Jews and Muslims. As I learned more about life in other parts of the globe I began to realise how lucky I was to live in such a rich country, in a society free from intercommunal violence, where human rights abuse was the exception rather than the rule, where the overwhelming majority knew they need never fear starvation or homelessness. This multicultural society wasn't perfect, but compared to much of the rest of the world, and much of the rest of human history, we were doing pretty well.

So when I first heard the BNP leader saying that "The multicultural experiment has failed", I laughed. If this society was a failure, what was a success supposed to look like? The only "monocultural" society that came anywhere near to Britain in economic terms was the People's Republic of China, and I doubted that this was the alternative Nick Griffin had in mind. So what was the evidence? Well, there were some riots in Bradford and Burnley. In 2001. Which the BNP had helped to organise. Shops were looted, cars got torched. A pub got burned down, and everything. And then? Well, then it all got cleared up and everyone got on with their lives.

Much as I wanted to believe Nick Griffin, it hardly seemed like knockdown evidence. I mean, all credit to the BNP for trying, but compared to Bosnia, Chechnya, Rwanda, Cambodia, Sierra Leone, Kosovo, Nepal, Afghanistan, Guatemala, Laos, Vietnam and Thailand, Nick's burgeoning civil war really wasn't very impressive. I kept waiting for my non-white friends and neighbours to torch my car, kill my children and burn down my house but it just wasn't happening.

But then things got really confusing. Trevor Phillips, the head of the Commission for Racial Equality, started agreeing with Nick Griffin. Multiculturalism hadn't just failed, he announced, it was such a bad thing that we shouldn't be using the word any more. Polly Toynbee, who was obviously a bit short of "hot issues" for her controversial Guardian column that week, agreed with him, although being Polly Toynbee she was careful not to say anything that hadn't already been said by somebody else. Then everyone piled in. It was like one of those bar fights you see in Western movies. In the end, people started forgetting how the fight got started, but that didn't matter because so many people were now involved that it had become a Mainstream Issue.

Multiculturalism was bad, said Trevor, because it meant segregating people. Multiculturalism was bad, said Polly, because of "unctuous, unthinking platitudes about the richness of all diversity". Multiculturalism was bad, said Nick Griffin, because it allowed lots of dangerous Muslim types to come and live here. Yasmin Alibhai-Brown had already written a book with the word "multiculturalism" in the title, so she got to say whatever she wanted.

Since then it's all got a bit crazy. Now everyone seems to be saying that multiculturalism is a bad thing, and offering their own set of solutions. The great thing is that you can more or less make up your own personal definition of multiculturalism, kind of like those pizzas where you get to choose your own toppings, and then attack it to your heart's content.

Trevor says that multiculturalism equals a kind of "Apartheid-lite", which surprises me because I always thought it meant the exact opposite. Polly says that multiculturalism stops us from outlawing discrimination against women or condemning suicide bombers. The British teenagers who get involved in terrorism, she insists, "inhabit a different cultural universe" from the rest of us, and that's the problem. The solution, she and Trevor agree, is "a universal coming-of-age ceremony to give meaning to adult citizenship, along with the right to vote and eventually receipt of the matured baby bond". That's right; we can beat the evil threat of terrorism by giving everyone an ISA and making them swear an oath of allegiance to the Queen.

Trevor and Polly both seem to think that we can learn lessons from the way the French do things, which I find a bit confusing, because putting all your immigrants into huge out-of-town ghettos hardly seems to be the best way of promoting integration.

I can't help but think that Trevor, Polly and Yasmin, in their desperate rush to say something that hasn't been already been said before (keep trying, Polly), have grabbed on tight to the wrong end of a rather enormous stick. Nick Griffin, meanwhile, is loving every minute of it. Because he knows that whatever nuanced, post-modernist definition Polly, Trevor and Yasmin are using, the vast majority of us still see multiculturalism the way that we always have - ie. people from different cultures living together as equals. Despite the best efforts of the London bombers and the BNP, most of us still believe in it.

Many of us don't make any great distinction between multiculturalism and multiracialism. And when we hear the mantra, endlessly-repeated in the media, that "multiculturalism has failed", what many of us hear, many who are rather more easily-led than Polly and Trevor, is that "multiracialism has failed". Funnily enough, that's exactly what the BNP, in the aftermath of the London attacks, have now started saying openly. Nice one, Polly.