>What's the strong case against population dwindling other than supporting aging population? Given the AI armageddon,

Because you're not "dwindling the population" in the way you think. You're not taking an "8 billion" number and changing it to "4 billion". You're taking this growing organism, and switching it into a shrinking mode. Worse, you're changing it to "shrinking mode" in a way where you can't switch it out of that mode. It will, by necessity, shrink to nothing.

And it shrinks quicker than you could imagine. When fertility rates are at 1.0 (China), each generation is one half the size of the previous. It doesn't seem like much has changed... there are 4 or so older generations that are still large (but non-reproductive). When you have a 0.5 fertility rate (South Korea), each generation is one quarter the size of the previous.

Human extinction only takes about 12-14 generations at that rate. Less than 350 years. Even before it gets that far though, things get awful really quickly. It's not as if it's 350 years, and then everyone's gone. Those last few generations have no technology, they're huddled around in the dark trying not to starve.

>If there's less population, we need less production and less workers.

This isn't as true as it sounds. Some of our technology does not scale downward. If you need a nuclear power plant, this has a minimum number of workers. Even if you only want half the power, you can't get away with "half the workers". So, as there's less population, some technology will have to be abandoned. If you just employ people at the power plant despite that, then you're by necessity pulling those people from some other industry... it's an opportunity cost thing, and you have fewer opportunities.

Sub-replacement fertility is human extinction. Not in 10,000 years, but in just a couple of centuries.

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ahtihn an hour ago | parent [-]

> Those last few generations have no technology, they're huddled around in the dark trying not to starve.

At that point, the birth rate would quickly rise again, no?

Because if you're back to living in a pre-industrial society, kids suddenly have value again.

So it's likely that either there's a point of equilibrium or the population keeps swinging up and down. Total extinction seems unlikely.

	▲	geodel 39 minutes ago \| parent [-]
		Indeed. And in context of India since that's what Economist's article is about. Having higher population growth is just insanity to me. After destroying land, water, air, forests, mountains and still barely enough for hundreds of millions souls I am not sure how population deflation can be a important concern at this point.