Peter: But of course numbers matter, and of course aesthetics is important (I argued that point in a previous post). A thousand people living on a one-sq-km island is not at all the same thing as a million people on a 1,000-sq-km island. That densest quarter of the Chinese–over 300m people–are living on 450,000 sq km. That’s like putting the entire population of the USA into California. Supposing we were to do this, Americans would feel overcrowded. If the rest of the country was uninhabitable desert, it would be no consolation to them to hear you say: “Yes, but your country as a whole isn’t overcrowded.” I think we are just working from different definitions. For you, a nation would be “overcrowded” if it would be demonstably better off with fewer people. To me it’s overcrowded if a large number of citizens, on being asked, would say: “You bet it’s overcrowded!” I’ll grant you, it is possible that that person’s grandchild might say: “Grandpa was wrong. We just needed a few technological fixes, and there’s plenty of room for everyone.” That is a possibility. Another possibility is, that the grandchild might die in infancy as the result of some ecological catastrophe brought on by overcrowding. You are dealing in hypotheticals. I don’t know how you could prove that the one thing is more probable than the other. Certainly not by appealing to the 1880-1920 Great Wave of immigration into the US. That was one time and one place. It was not all of US history, and US history is not all of history. In any case, do we know for sure that our country was improved by it? Has this been rigorously demonstrated? (Yes, yes, I know, the immigrants and their descendants were much improved by it. That’s not the question.) I have seen somewhere that if there had been no immigration into the USA at all since 1790, the country would now have half its present population. What would be wrong with that? My guess is, we would be just fine. We would have lost much–the Broadway Musical, for example–but not knowing we’d lost it, we wouldn’t miss it. We wouldn’t be starving, or cutting each other’s throats. We’d probably be a sleepy, cozy, loose federation of Scandinavian-style social democracies. Not my cup of tea, but not hell on earth.