I think it's less about preserving sparkling blue eyes and more about the negative effects of a declining population on a country's economy. Sam Harris had a guest (Peter Zeihan) a few episodes ago who talked about the downsides of population decline, and he was pretty interesting.
One of the key points he made that seemed fairly intuitive is that as your population declines you eventually wind up with significantly fewer long term experts in various fields of science and engineering. This means that the people who train up the next generation of scientists and engineers are spread thinner, and therefore less depth of expertise in those fields as the decline continues.
I'm not sure how much that idea is backed up by evidence, but it at least makes some sense.
Population decline had never really registered as a problem to me until I heard that episode - I always kinda figured that less people around would be a net good. Definitely worth a listen if you're interested in the topic.
> One of the key points he made that seemed fairly intuitive is that as your population declines you eventually wind up with significantly fewer long term experts in various fields of science and engineering.
Good thing we have books, the Internet, billions of video recordings, et al.
Minor nitpick - Sam is not the one making these points in the referenced episode - it's the guest who wrote a book on the topic. In fact Sam brought another guy onto this show to act as a backstop, admitting up front that he didn't feel he knew enough about the topic to have a deep conversation without some help. The other guy pushed back on various points that Zeihan made and it's a pretty interesting discussion.
As for immigration, no arguments there. But that point leads back to the question of why a society hits population decline in the first place. Presumably the same things that cause your "native" population to stop reproducing eventually affects your immigrants after a generation or so, so while it can definitely slow the population decline, it's not a full solution.
To your point about the loss of deep expertise - I think the problem is still worth thinking about. Yes, we can make new experts. And those experts might even be more productive than the last generation of experts. But at the end of the day, it takes longer to make them, and you still have less.
I'm not sure how much I agree with Zeihan, but he makes some interesting points which I hadn't previously considered.
>Presumably the same things that cause your "native" population to stop reproducing eventually affects your immigrants after a generation or so, so while it can definitely slow the population decline, it's not a full solution.
I think it could be a full solution. In theory there could be 2 populations, a slow population and a fast population, and the fast population continually donates people to the slow population via immigration to sustain it. The worry would be if some idea from the slow population infects the fast population and causes it to slow down.
That point doesn't seem particularly intuitive to me. A society in population decline is a society where the old outweigh the young. You would seemingly have a higher ratio of long-term experts to young learners than you do under a population growth scenario.
If there is a risk, your risk isn't that you have too few experts to offer training, it's that the young learners are spread too thin. There aren't enough people looking to learn for all the people who have knowledge to pass down and so you lose knowledge in that transition.
--------
With that said, I find the general premise that we would be looking at some kind of dark age with the level of population decline any of us are likely to see in our lifetimes, nearly comical.
The global population now is around 8 billion. It was around 3 billion in 1960 (4 billion in 1974, 5 billion in 1987, 6 billion in 1999). It doesn't seem to me that the pace of change or technological advancement was particularly slow in any of those time periods, and the substantial productivity gains since then would alone suggest that we'd be more efficient for those population levels than things were at that time.
One of the key points he made that seemed fairly intuitive is that as your population declines you eventually wind up with significantly fewer long term experts in various fields of science and engineering. This means that the people who train up the next generation of scientists and engineers are spread thinner, and therefore less depth of expertise in those fields as the decline continues.
I'm not sure how much that idea is backed up by evidence, but it at least makes some sense.
Population decline had never really registered as a problem to me until I heard that episode - I always kinda figured that less people around would be a net good. Definitely worth a listen if you're interested in the topic.