There is much talk of incentivising fecundity. It did not work for Imperator Augustus, nor will it for us, for a simple reason: kids are a pain in the arse. And land grants for chavs are probably not the best idea; need I explain why? One must differentiate based on intelligence or education level (a proxy for the former) to avoid pouring money into the sewer, and since no earthly government has the balls for that, we can forget it.
Alternatively, technology promises that which the Romans could scarcely have dreamt of. The demographic “problem” is not low fertility. Only in light of mass migration, which need not be, is low average fertility bad, and selection pressure will deal with that regardless. The problem is that the cognitive elite are infertile. Conversely, would the African population explosion be worrisome if the children all had IQs upwards of 180?
Even if you adhere to an ethical system such as libertarianism and so place all emphasis on freedom from coercion, there is a lot to be said for a state-enforced rewriting of human genetics, perhaps even a global one – setting aside the practicalities thereof. If the rewrite is imposed on all, well, there goes the problem of an inherited continuity of stupid. I am sympathetic to a lot of anti-paternalist intuitions where paternalism is liable to exacerbate a problem or make no odds, but it does make odds when one contemplates a future of regression to the mental acuity of orangutans. There will be no liberty then, nor indeed anything worth speaking of (assuming people could still speak). The desire for paternalism often arises from the knowledge that most people have poor reasoning abilities, but that need not always be, thanks to forthcoming technological interventions, too numerous to list. True, this may not be coming soon. What was that about caring for the long-term?
As per, pessimism is sensible. In the zeroth approximation, bet on China. Beyond that, don’t bother. This is where we are at.