Migration does not merely bring units of labour or transfers of capital. In fact that is the most benign aspect of this subject. Nobody has a problem with his fellow man looking for his next opportunity, not even the most rabid nationalists I know, and doubtless as NRX I know more than most.
The central problem is something that at first appears to have nothing to do with migration. Namely; how is wealth actually created?
There are many answers to this question. Nearly all the obvious ones are wrong. This is amply demonstrated by the fact that almost every aid program, every economic structuring program in developing countries has repeatedly failed.
I suggest that we don't actually know the answer. Perhaps we do not have all the correct axioms. Perhaps extrapolating from having the correct axioms is just infeasible. We do not know why nations rise or fall. There are just people who pretend to.
What we do know is history and the present.
In history we know 4 centuries ago English and the Dutch began growing at quite a different trajectory to the others. They were gradually followed by most European states.
In the present the most powerful nations on earth are the result of that outgrowth, with the Asian Giants only coming onstream very recently roughly a half century ago.
I believe there are two things to take note here.
1. Whatever economic growth is, it doesn't transmit itself parsimoniously via word of mouth. We also know it has nothing to do with education, unbelievable though that may seem, there is ample evidence for this. North Korea is quite literate. The Communists were in general quite well read even as they fucked their countries into the ground. There are many African schools filled with enthusiastic learners (and disappointment when the economy proffers no value to much of this learning).
2. Economic growth is very discriminating. Based on culture. I think of culture as a collective idea network. There is a Occidental culture, there is an Oriental culture. The Occidental one grokked economic growth first, followed by the Japanese, Singporeans, Koreans, Taiwanese and then the Chinese with their SEZ. With the exception of the Japanese, that was very slow... suggesting that there is something... not simple... going on. The Asians after all are often very talented individuals. This is something about the collective.
Plainly the cultures that did not grok economic growth at all are the Africans and the Middle Easterners ex Israel. That may be starting to change with Iran but it is early days yet. Having oil is like winning a lottery ticket, the native economies are extremely impoverished and w/o oil...
Plainly the 'Protestant Work Ethic' is rot. Economic growth is not native to white people and certainly not a particular religion. Despite that, the cultural explanation makes most sense in light of the economic disparities.
The interesting thing is that we know it is culture because of colonization. We know it is in the particular people but not necessarily in the genetics or their education.
If you have large numbers of migrants from MENA, places that have not grokked economic growth, then they are bringing a dysfunction with them. They may be carrying a silent burden, a deadly memetic anti-matter, and don't even know it.
The individuals may be nice. Non-terrorists. Non-religious even. Friendly and civic minded neighbors. None of that matters if their network, which does not produce economic growth interferes with our network that does.
This is the great fear that afflicts nationalists instinctively.
Because again, if culture is what drives economic growth, and signs points to yes, then absorbing another culture which does not will lead to lots of little zero sum games, culminating in crime, terrorism and finally in broad conflict. You see it happening in France today, it is gradually but surely turning into a horror show.
That is the problem I never see addressed by migration discussions. No, not race, not genes, but the network problem.
Economists by the way know all of this. They just choose to call what I'm talking about 'institutions'. They really are spineless. What are institutions but groups of people acting in a certain way, namely; a culture.