http://www.guardian.co.uk/commentisfree/story/0,,1990573,00.htmlMigrants from poor countries working in rich ones send home much more - $200bn a year officially, perhaps another $400bn informally - than the miserly $80bn western governments give in aid. These remittances go straight into local people's pockets, paying for food, clean water and medicines, enabling children to stay in school, and benefiting the local economy. Just as EU trade barriers that prevent African farmers selling the fruits of their labour in Britain are unfair, so are immigration controls that stop Africans selling their labour here.
Immigrants also make native workers more productive: nurses from the Philippines allow doctors to provide more patients with better care. They also add diversity and dynamism, stimulating innovation and enterprise, and thus economic growth: witness the buzz of a cosmopolitan city such as London. Innovation most often comes from groups of talented people sparking off each other. If they have different perspectives they can solve problems better. Look at Silicon Valley: Intel, Yahoo!, Google and eBay were all founded by migrants.
Undeniably, learning to live together can be tough. Yet closing our borders would not reduce the terrorist threat from a tiny home-grown minority, while anti-immigrant rhetoric fuels hatred towards existing ethnic minorities. While concern about entrenched segregation is understandable, the real issue is not multiculturalism, but social exclusion. Nobody is terrified of rich whites clustering in Chelsea.
As for shared values, society is broad enough to accommodate nuns and transsexuals, Marxists and libertarians, eco-warriors and city slickers - but we must all abide by parliamentary democracy constrained by fundamental principles such as freedom within the law, equality before the law and tolerance of differences. And while we fall well short of the lofty ideals of liberal democracy - discrimination is rife, tolerance limited - they are still the standards we aspire to and the basis of our peaceful coexistence.