You make me wish I knew more about Rome.
It’s a good reminder that Rome had an identity/value for individuals to buy into. I think it’s true, and it’s probably also true that Germany or France do not have similar non-ethnic identities; however, they certainly seem to stand for Western-style tolerance and economic mobility. And — on the other hand — the US still has an ethnic component to its identity, though it’s certainly more multi-ethnic than most European countries. So I’m not sure the problems with multiculturalism lie so much in the ideal of the country as in the execution of multiculturalism.
Take the example of the Goths in the Roman Empire. The Goths were partially admitted as soldiers, but many came as “refugees” from the Hun invasions of AD 375, in return for military service. Their mistreatment at the hands of Rome, essentially Rome’s refusal to apply their usual tolerance/multiculturalism to these “barbarians,” led to deep Gothic bitterness and eventual uprising against the Roman government. In this case I think we see danger for the modern West — an ideal of tolerance or justice is worse than no ideal at all if it ends up being a hypocrisy. Some refugees I talk to are more angry at Greece (which has sheltered them from war or distress) than at Saudi Arabia (which refused entry to most in the first place), because at least the Saudis were honest in the beginning.
And indeed, I think it needs to be made clear that I don’t think multiculturalism means unlimited immigration (nor do I think you assumed that — just for my peace of mind). Multiculturalism is more of the policy followed after migrants arrive: tolerance, kindness, a level of autonomy, and a level of participation in national culture/governance. Like the Amish within the US are given space to live their culture peaceably, as long as they respect the law and don’t conspire against the government.
Of course, some people emigrate for better opportunities and become disillusioned by what they perceive as the hypocrisy I mentioned earlier. That seems to be one of the major reasons for radicalization of Muslims in Europe and for the creation of urban second-generation gangs in the US. And this is a serious consequence of adopting multicultural policy, of not requiring assimilation or of not refusing immigration altogether. Multiculturalism has its risks. The Roman Empire experienced the consequences. For the time being, I’m merely arguing that the potential upside is greater than the potential downside.
All right, I’ve gone on long enough. On the Crusades, I concede your point — they were not entirely monocultural, depending on the Crusader Kingdom, and the caliphates fighting them certainly were not shining examples of multiculturalism either. The Spanish Reconquista would, frankly, have been a better example of a group requiring monoculturalism. And your point on cities is very good as well — city does not equal multicultural, though perhaps they are more likely to be so.
And I love your thoughts on hospitality to strangers in ancient and modern times. We really are, as a human race, less likely to treat strangers hospitably. I’ve thought of it briefly, but have no theories of my own. Will have to ask yours sometime.