When I argue about immigration policy with libertarians, we very quickly realize that we’re talking past each other.
The libertarian case for open borders goes like this: There are people in poor countries that want to come to rich countries. Preventing these poor folks from coming into a rich country is effectively forcing them to live in poverty. Allowing them to come to a rich country would make them richer, and therefore better off. After all, we’re all people – they’re just poor. Here’s Aretae stating is about this simply.
I can see this line of reasoning working if you favor immigration on a relatively small and selective scale, but in no way do I understand how this line of reasoning works for open borders.
The key question here is: if borders were really open, how many people would actually move to the US? As is so often the case, the only person who’s tried to answer the question is Steve Sailer.
Let’s round down a bit from these estimates and say that one billion relatively poor people move to the US.
It seems obvious to me that if a billion poor people moved to the US, conditions in the US would . . . deteriorate. I’d go so far as to argue that the world would end up a worse place without a rich and productive US. Therefore, we can’t have open borders, since it will make everyone worse off.