Issues of population, multiculturalism and immigration have a recurrent tendency to boil up in political and media discussion. Which is curious because there is very little that is novel about the principles involved, although practical political choices, for instance about immigration, make some folk acutely uncomfortable. The chief criteria for recognising a society as a nation or more particularly, as a nation-state, are reasonably well understood. In our world the concept of “nation” has for some three centuries or more revolved around the notion of ethnic and cultural homogeneity. In fact, homogeneous national cultures have become the norm for modern…