I'm not going to tell you that there won't be problems caused by increased migration. Anything that changes the world so much will cause problems. I'm not going

I'm not going to tell you that there won't be problems caused by increased migration. Anything that changes the world so much will cause problems. I'm not going to tell you that America's material wealth is the result of "random chance", either. But I do think that quite a lot of it is the result of centuries of immigration, each wave of which was met with much the same objections. It's one thing to caution against removing all barriers literally overnight. I don't know that it would be a disaster, but I don't know for sure that it wouldn't, and it's reasonable to exercise some caution. But, at the risk of making an inflammatory analogy, it would have been morally defensible to ask if there was a way to end chattel slavery in the US without a civil war that killed ~3% of the population. It was not morally defensible to oppose ending it. Global apartheid is an evil of a similar scale, and first world governments its active cause, not innocent bystanders. It is our duty to figure out how, not whether, to end it.