The current refugee surge into Europe has caused a lot of my friends who are immigration restrictionists to say this proves that I am naive.
During the Cold War, we (including most Conservatives) considered it immoral that Communist countries would not let their people leave (Berlin Wall, etc.). Now, however, it is argued by many of these same folks that it is imperative that the Western democracies build walls to keep people out.
So here is a question -- not of practical consequences, but of pure morality. Consider this picture of people being prevented from crossing the border.
Explain to me why this scene is immoral if the wall and police forces were put there by the country at the right (the leaving country) but suddenly moral if the same wall with the same police force were put there by the country on the left (the receiving country). Don't they have exactly the same effect? Same wall -- How are they different?