We are currently experiencing a human-induced mass extinction event and reduction of biodiversity comparable to the largest natural catastrophes in the planet. The way things are going, by the end of the century most of the large mammalian predators will be definitely extinct, and if carbon emissions are not reduced by the end of the century, by which we should become a carbon-negative society, the oceans will not be able to support most of the base of its food chain.

I question your valuation of human society above the base of the biological systems that support its very existence. A large population living in a humongous wasteland is of dubious utility for its inhabitants.

I reckon you haven't been able to see the true impacts of humans on most of the ecosystems in the planet. Ultimately, I think you're confusing density with population; a large population is not a requirement for a dense population. Furthermore, the percentage of the population that contributes to innovation is a very, very restricted subset of it.

Nobody is being thrown overboard. The article is just pointing out that it may not necessarily be catastrophic if population growth slows or even reverses for a time. We're all just speculating, whether you agree or disagree.

In support of the article, slower population growth would reduce resource consumption. Rampant population growth would speed up the resource depletion process. As certain crucial resources become more scarce, conflict is likely to follow. It'd only be a matter of time before large scale war followed, perhaps leading to an extinction event.

There are definite positives and negatives to slowing growth rates, but I think there are probably more positives if we're talking about a gradual slowing (as opposed to a sudden tanking). We can do a lot more with a lot less today. Many of us don't need massive families anymore, and that's OK.

You try to patch it, but it also makes a lot of sense to stop bringing more people onboard. Lowering birth rates is an example of the latter, not of throwing people overboard.

How much density is needed to make progress? At which point too much density becomes a danger and what kind of danger?

I guess that there might be already some answers to these question. And in my opinion it IS important that we start talking about this. Because the only discussion that I hear until now is that many countries have not enough children (e.g. Japan, Russia, Germany, Italy - just to name few that I have seen in print media in Europe) which is seen as a danger. But talking about socially and psychologically positive solutions how to better distribute population density - nobody is speaking about this. I guess that one of the reasons is because we still think in national boundaries. But this is not the only one. I think the deeper reasons might be more on an instinctive level? I do not know, but I find it good that we start talking about un-growth of population instead just having a taboo.

But, yeah, patch the raft. And stop having 4 kids.

I am told BART was approved by a whole lot of voters who liked the idea of everybody else using BART, so they could have less traffic on the roads. Nobody was voting for BART so they could use it themselves. (Or so the story goes).

Without a fresh supply of young workers, but with all the factories/tools/capital/housing that supported a larger population, the benefit of incremental workers becomes gigantic.

The winning regions in such a scenario would be those that welcome massive immigration to maintain production.

Even assuming some xenophobic fear arising from the uniqueness of the zero-fertility situation, nations like the UK or US, that already have the benefit of worldwide adoption of its language (and cultural exports), and functioning beachhead immigrant communities of all types, would in such a scenario be most likely to recognize that immigrants could soften the pains of a population-shortage.

Keeping immigrants out would require even more of the dwindling population wasted on 'guard labor', and even more empty buildings/communities and idle factories. And to the extent that there are culture clashes – there's now plenty of space to congregate in voluntarily-segregated communities, but still within the same national boundaries for easier trade.

So while I loved a lot about the 'Children of Men' story/movie, its economics were all wrong.

I'm partial to the idea that geniuses have one or two great ideas in them per lifetime, regardless of how long that life lasts. Given 150 years of life, I don't think Picasso would invent cubism then something else.