But it is happening independently of social campaigns to cut back on population, and that was just my point. That is not engineering a change in social behavior. That is people living their lives normally and not changing their behavior because of a movement not to have children.
Yes, that's my point too.
Social engineering is not only hugely difficult, and very unpleasant; It's also completely and utterly unnecessary.
There's nothing so useless as to do, with great efficiency, that which should not be done at all.
You are looking at a massive rock that has been pushed off a cliff, and saying "How on Earth are we to solve the dreadful problem of this rock being too high up??".
You haven't demonstrated that the height of the rock is problematic, but even if we accepted your assertion that it is, it won't be for long even if we do nothing at all. The best strategy here is to do nothing at all.
Population isn't too high, isn't increasing exponentially, and within a few decades won't be increasing at all.
The only "problem" is that so many people are convinced that there's a problem, and are hell-bent on making other people miserable in an attempt to mitigate the problem that doesn't exist.
We don't need to engineer a solution to the problem of overpopulation, for the same reason that we don't need to engineer a solution to the problem of water running uphill.
We should ensure a good education for as many people as possible, for a million excellent reasons. Population control isn't one of those reasons.
It might, with great effort, be possible to force humanity back to exponential population growth; But the first and most difficult step towards that completely stupid and pointless goal would be to stop educating almost everyone, and that would be practically impossible to achieve at this point, because even the uneducated can now see that education is the way to improving their lives.
You couldn't make exponential population growth back into a problem if you tried.
All movements for people not to have children are both needless and futile, and serve only to enable the authoritarianism of the members of such movements. They are therefore evil.