The Borders of Liberalism
If one is looking for an abstract principle to follow on questions of immigration, liberalism cannot provide it. What is clear, however, is that liberal societies must not only uphold the ideal of openness to others, but must also demand openness on the part of their new members.
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When it comes to whether and how to regulate the economy, Western societies have a history of liberal theory upon which to rely. But when it comes to immigration, there is not much in the liberal tradition to which they can turn. As a result, in both Europe and the United States, much of the debate over immigration is dominated by illiberal voices, the most insistent belonging to politicians who promise to protect the cultural integrity of the homeland against the presumed degeneracy of the alien.