Re fertility decline, yes, as the main change in the last half century is the number of women who become moms, not the number of kids per mom, all we need is a larger fraction of women having kids. Yes, as that used to happen, it must still be feasible. Yes, a big enough subsidy per kid would work, and we could make the new kids pay for that via government debt. And yes, as we’ve seen fertility rise at some times and places, there’s historical variation that we could plausibly mine to find factors to promote fertility.
However, it takes voters who want more kids to vote in politicians who promote them. After all, the cultural ask re higher fertility is huge, plausibly even larger than to cut carbon emissions. The trends to be opposed are in both cases deeply embedded in existing culture, and in ways that most of us treasure. Societies in history that have loudly lamented fertility declines, and tried to reverse them, either among elites or more widely, have consistently failed. This includes recent versions of our societies. Our world’s fertility decline has been pretty consistent for ~2.5 centuries, and local deviations have so far always been temporary.
Thirteen years ago I guessed fertility to be our biggest problem, but didn’t let it distract me much. Two years ago I guessed that insular fertile subcultures is how fertility decline will end, but still didn’t let the topic distract me. A few months I realized that innovation would grind to a halt during a declining economy, and since have read and talked much on the topic.
Alas this has confirmed my worse fears. I’m not sure quite how best to persuade you all of this, but world population will soon fall fast, and then unless we achieve full AGI or end aging by then, our total world economic capacity will also fall, with scale economies and innovation rates both falling roughly in proportion. Actually innovation will fall faster due to diminishing returns, populations getting older, and lower-than-Western African innovation quality.