Quoted in a thoughtful discussion at David Thompson about the Left's internal conflict between internationalism and nationalism:
The justification for giving priority to the interests of fellow citizens boils down to a pragmatic claim about the value of the nation-state. Without fellow-citizen favouritism, the nation-state ceases to have much meaning. And most of the things that liberals desire - democracy, redistribution, welfare states, human rights - only work when one can assume the shared norms and solidarities of national communities.
Read the whole thing.