I'm generally sympathetic to the idea of open immigration. At least in the context of a free economy. And I believe in the right to keep and bear arms.
But then there's this thought-experiment where uniformed Russians show up at your border with weapons in hand. Do you wave them in?
Of course it's absurd. It's a thought-experiment! They run to the ridiculous. But, no, you don't let the Russian Army in.
The question is: when does immigration morph into invasion?
Curiously, the ecologists are always talking about "invasive species"... wouldn't it be more circumspect to refer to them as "thriving immigrant species"?
Of course, in the thought-experiment, we're all the same species, and what put me in mind of it is the mess in Europe.
Is Europe ready to be a melting pot?
I fear that really it's not.