Mickey Kaus has an elaborate theory of social equality vs "Money Liberals" that I don't really understand, but that also leads him to want to kick unauthorized migrants out of the United States and curtail the ability of future migrants to come to the United States. To my way of thinking, that involves completely discounting the interests of human beings who happen to have been born in Mexico or Morocco or Mali. They are perhaps reasons for deciding that people born in Boston or Birmingham count more than people born in Bangladesh or Bolivia, but they're nationalistic reasons not egalitarian ones.
At any rate, in responding to me on this point he suggests that cosmopolitanism would lead to disaster:
I leave it to you to imagine the real-world consequences of Yglesias’ position. (Hint: Blade Runner set in Brazil!) But what about my position? I would give Americans priority in the competition for low wage jobs. I worry more about whether they can make $12 an hour than I do whether Mexicans who may have made only $2 an hour are able to come here and make $8 an hour. “We take care of our own”–even though the jump from $2 to $8 might be a huge income boost for the immigrants, who are indeed “people too.”
I love Blade Runner but I think some data might help elucidate this point. According to Gallup there are 150 million people around the world who say they'd like to move permanently to the United States. Right now the United States has about 89 residents per square mile. Add another 150 million people and we'd be at around 135 people per square mile. How would that stack up in context? Well, France has 303 people per square mile and Germany has 593. Japan has 873. The Dutch have 1,287!
All those places have their share of problems (and so do we) but none of them are exactly post-apocalyptic hellscapes. I've never been to Japan, but the other countries are all quite pleasant. German cuisine would benefit from more immigrants.
Now that said, it does seem like the sudden arrival of 150 million new people all at once would overtax American infrastructure. Some kind of phase-up of permitted immigration levels (perhaps tied to a residency permit auction) would be a lot better than a sudden leap to an open borders policy. But the United States ran an open borders regime throughout the 19th century and we weren't worse off for it. On the contrary, it laid the foundations for American greatness. Shifting back in that direction—with exceptions for dangerous criminals and other select problem types—over time seems perfectly feasible to me and would substantially increase overall human welfare. Now obviously that doesn't resolve the question of whether or not, morally speaking, it makes sense to simply not care about the interests of foreigners. But Kaus and I agree that foreign-born people are people, so for my part I'd like to take their interests into consideration.