The most pressing issue today is best summed up in the question asked by Rodney King after the Los Angeles riots over a decade ago: "Why can't we just get along?"
The US struggles to find a balance between their need for Hispanic migrant labour, and the challenge this poses to Anglo domination of its culture. We are asking the same question about migration from Eastern Europe and Africa. In the Middle East Jews, Christians and Muslims struggle to find a way of living together. And in the EU as a whole we agonise about the place of Muslims. We are all trying to find the answers to the implied questions - how can people of very different cultures find a way of sharing the same space?
In this country much of the debate about these issues has been encapsulated in three arguments: n Is the current level and nature of immigration positive or negative for the UK, socially, economically and culturally? n Has our historic policy of multiculturalism led to a more integrated or polarised society? n Do we need a more explicit assertion of our common national identity, our Britishness; and if we do, how should we express and promote that identity?
We desperately need immigrants to sustain our workforce. But in this new world of more rapid and diverse immigration, coupled with an unprecedented threat to global security, we cannot pretend there are no costs faced by our changing communities. Ruth Kelly's call for a rational debate about how to assess and manage those costs is both timely and bold.
Her words were especially courageous, since she knew she would be tilting at the unquestioning acceptance of the doctrine of multiculturalism in most of our political, media and academic establishment; she publicly backed what you might call the integrationist heresy.
Ruth Kelly's call for honesty should not be the excuse for every anti-immigrant, Muslim-baiting wingnut to hijack the debate to advertise their latest assault on some part of the community.
Take for example the calls for racial profiling in the wake of the recent - and welcome - uncovering of a plot to carry explosives on to British aircraft. We need to be straight about it - you can't tell how someone worships by looking at them. So there is no such thing as religious profiling - it has to be racial.
Everyone knows that we have to find new ways of tackling new threats - the terrorists will be ruthless and creative, and we have to respond in kind. Whatever the causes of terrorist actions, we, whatever our faith or race, have a shared interest in taking steps to stop them. I'll wait in line at the airport however long it takes. I'll give up the hand luggage. And I'll gladly accept that if the specific intelligence says that today's threat is likely to come from middle-aged black men with glasses, I am more likely to be stopped and interrogated than my teenage daughter.
Security has to be our first priority. But those steps have to reduce the threat, rather than increase it, and since Muslims, like Christians, come in all shapes and colours I can't see how religious or racial profiling will deal with so-called Islamic terrorism.
That is why in the US, most police and security authorities reject racial profiling as clumsy, and ineffective.
Any 16-year-old with a GCSE in media studies will tell you what even the suggestion of racial profiling will produce: first, greater effort by terrorists to recruit, bribe or intimidate non-Asians into terrorist activity. And second, a completely unnecessary sense of being picked on amongst British Asians - who I think have been remarkably tolerant of the focus on them so far. And let's remember that focus recently included the shooting of a young man in Forest Gate.
We all want the security services to do whatever they need to do to protect us. Surely the key here is patience and professionalism, on the part of the security and intelligence services; and also on the part of those of us who are engaged in the delicate task of building confidence in Muslim communities so they become allies in the fight against terrorism.
Policy should never be driven by political expediency or whim. Policy should be there to change things, not just so that our leaders can make us feel better.
We cannot build policy on what we would like to be true about people's lives. Instead of grasping at cultural straws, we have to work with what we know to be true.
So what do we know?
There are more cities with high segregation between Whites and Asians than between Whites and Blacks or Whites and Non-Whites.
However, the highest levels of segregation anywhere are those recorded between Indians and Pakistanis in north and west towns.
We know there is a mix of reasons why segregation - residential, psychological or social - takes place. One reason is sheer economic and social inequality. If you are more likely to be unemployed, less likely to be well-educated and live in poor housing your chances of meeting others and making friends outside your immediate community are poor.
Another is cultural - some people want to be near their church or mosque or synagogue, or near the shops or hairdressers that cater to their community.
A third is history, particularly for migrants recruited to a particular trade or factory, and who settle near their place of work.
And fourth, there is protection; for Jews who came 100 years ago, Asians who came 40 years ago and even the Eastern Europeans arriving now, all of whom may be subject to abuse and violent assault by a minority of their neighbours, there is safety in numbers.
None of these factors leading to segregation should necessarily lead to the formation of communities that are shut off from the outside world, but that is what we are seeing emerging.
The real crisis lies in the areas which the middle-class minorities have left behind; the areas which are becoming increasingly ethnically concentrated and exclusive. And the institutions which should be the engines of integration in these areas are failing to fire. In particular the public education system - which should be teaching our children to live together - appears to be achieving the very opposite of integration.
The colour and culture of societies has changed: cultural homogeneity is a thing of the past. Globalisation has made the politics of identity the true politics of our time. And in recent months it has been dramatised by the debate over migration.
What is more at issue at the moment is the degree to which communities can cope with the speed and scale of change. Half of all migrants arrived in the UK in the last generation and a third in the last decade.
There is the challenge of greater diversity of migration, and greater diversity of destination. Where we used to talk about ten or so ethnic communities we can now identify in London alone over 40 substantial groups of people with recent foreign antecedents. And whereas we used to assume that most migrants would settle in numbers in a few large cities we now see relatively small towns being settled by substantial numbers.
Thirdly, there is the challenge of greater transnationalism. When migrants arrived a hundred years ago, they more or less broke with the past. Today, international travel and communications mean you need not abandon the physical link with the past. Indeed, we expect that the majority of those coming from the EU Accession countries will return home within a few years. Even those who come from the Asian subcontinent now have a far more concrete relationship with their ancestral home.
The new migration from Eastern Europe however poses some major new issues for us.
The issue here isn't just numbers, though they do matter. But in a free market economy, the number of migrants generally speaking responds to our rate of growth or more concretely to the number of jobs available. There's no real evidence that anyone who wants one, and has the skills, is being deprived of a job.
So why are we so anxious
about this wave? First some facts. Ninety-eight per cent of applications for National Insurance numbers made by Accession country nationals between May 2004 and March 2006 were for employment purposes. The vast majority of workers are young and single, and only four per cent had dependent children with them.
In many cases Accession nationals are supporting the provision of public services in communities across the UK. Between July 2004 and March 2006, almost 5,700 Accession country nationals registered as bus, lorry and coach drivers and over 11,500 as care work-ers. There were 1,400 teaching staff; almost 550 dental practitioners; and over 1,750 medics.
But there are some features of this migration which make it very different to the post-Empire wave.
The first is pretty obvious. These people come to work, and to earn; they are young, often highly educated, single and child-free. In our last wave of migration most people came, did the jobs no one else would and rapidly brought their families to join them. The upside is that this is largely dependent-free migration; but it is socially significant - an influx of young men or of young women will change any community. And they can compete successfully for the better jobs with settled young workers. The growing number of migrants increasingly have their own institutions - places of worship, shops, even media outlets. There's nothing wrong with these preferences, but it means the range of areas in which we share experiences as a whole nation is shrinking daily.
Finally, there is factor that has nothing to do with immigrants at all. It is the continuing process of emigration, for centuries a feature of British life.
More Brits are leaving the UK than at any time since World War One and for every two Brits who leave only one returns. However for every two new migrants who enter only one leaves. The result is the composition of the population changes. There is nothing wrong with that, but we have to recognise what is happening and adjust policy accordingly.
We need a real, accurate understanding of the dynamics that are influencing today's society and we must not make things worse. We need long term and more sophisticated strategies in order to secure a cohesive, integrated Britain where nobody is sufficiently alienated to be attracted by extremism.
We cannot expect people to integrate into our society if they believe they are second-class citizens. The state has a responsibility to uphold the rights of all its citizens to fair and equal opportunities.
In terms of participation the CRE is undertaking comprehensive work to identify the reasons behind the democratic deficit this country faces and in particular the specific barriers to ethnic minority participation. Our Parliament is absurdly white and male. But even at the most humble levels of decision making things are little better.
We cannot expect people to integrate into our society if they believe they do not have a voice.
There are many things we could be doing and are doing but I am not Panglossian about this. These are merely contributions to a massive task. And we may not yet have got the tools right. Individuals, though they may be as engaged as anyone else can still choose a path of destruction and hostility. But we do know that the more we allow groups of people who live and work here to feel that they do not belong to this society the higher the risk of their taking hostile action against it.
But actually I am optimistic. Britain, despite the acute threats facing us today, is equipped in the long term to move from its current position of sleep walking to segregation. The majority of us, regardless of race, religion or class know that the freedoms, the lifestyle, and the mutual tolerance we enjoy here can not be matched in total anywhere else in the world. That of course is the essence of Britishness.
Perhaps the tide is already changing - who knows? What I do know is that we cannot afford to be complacent and the journey will be difficult.