Multiculturalism is a branch of Political Philosophy that deals with the proper way to respond to cultural and religious diversity. It is not a simple choice between alternatives as the Prime Minister would have us believe. There is a voluminous library of works on this subject that dates back to ancient times.
Multiculturalism includes not only the way to deal with the moral and political claims of immigrants who are ethnic and religious minorities but also of disadvantaged groups like women, children, gays and disabled people. It claims that culture and cultural groups are to be recognised and accommodated in a society.
Since language and religion are at the heart of claims for cultural accommodation by immigrants, for the Prime Minister David Cameron to condemn Britain's long-standing policy of multiculturalism as a failure , is a recipe for another violent confrontation between radical islamists and western governments. This will not combat home-grown extremism but rather fuel it.
Multicuturalism is a topic that must be handled with care. The question is what is the relationship between multiculturalism and the integration of immigrants? This has generated debates over centuries featuring great thoughts for and against and it will be a folly for one to dismiss any side of the discourse lightly.
My advice to David Cameron is for Britain and Europe in general to encourage a culture of contact and dialogue with the ethnic minorities. I believe his attack on immigrant multiculturalism is based on fear and anxiety about foreigners, and nostalgia for an imagined past when everyone shared thick bonds of identity and solidarity as native Brits.