Derb: Everyone here, at least, gets why importing young Gaza Palestinian men yearning for martyrdom is probably a bad idea. But I think a lot of people don’t realize the mathematical absurdity of his claim that “In the decades to come, North America and Europe will have to take in tens of millions of immigrants anyway to slow the aging of their populations.” We’ve actually looked at the numbers, and there just isn’t that much “slowing” possible; for immigration to have any appreciable effect on our country, it would probably have to be more like hundreds of millions. From our piece on immigration and aging:

* Looking at the full impact of post-1980 immigrants reveals that if they and all their U.S.-born children are not counted, the working-age share would have been 65.9 percent in 2000, almost exactly the same as the 66.20 percent when they are all included. …
* Looking to the future, Census Bureau projections indicate that if net immigration averaged 100,000 to 200,000 annually, the working age share would be 58.7 percent in 2060, while with net immigration of roughly 900,000 to one million, it would be 59.5 percent.

Is that tiny benefit, assuming it’s a benefit, really worth all the side effects?