I sometimes pose for my liberal friends a stylized thought experiment. Say that they live in a country of 3 million people (the size of New Zealand) where 55% of the citizens are pro-choice and 45% are pro-life (1.65 million vs. 1.35 million). Now the country is facing an influx of 1 million devoutly Catholic immigrants, who are 90% pro-life. If these immigrants are let in and become citizens, the balance will flip to 2.25 million pro-life to 1.75 million pro-choice (56% to 44% pro-choice); and what my friends might see as their fundamental human right to abortion may well vanish, perfectly peacefully and democratically.
It’s unlikely that any constitutional protection will stand in the way: Even constitutions can be amended, and new judges can be appointed. Nor can one rely on “education” or “assimilation” — what if the immigrants simply conclude that their views on abortion are just better than the domestic majority’s? I think many of the current residents may rightly say “We have nothing against Catholics; but we don’t want our rights changed by the arrival of people who have a different perspective on the world than we do.”
Letting in immigrants means letting in your future rulers.
If today’s immigrant wave were likely to vote Republican, all right-thinking people would be demanding deportations and a mile-wide belt of barbed wire and minefields along the border.
I wish I could get my more dunder-headed Libertarian and Objectivist friends to understand this lesson: If your supporting open borders results in an American culture that rejects and despises your philosophy, you would seem to be suicidal, eh?