43.7% of the population is still working age (25-65).
And in 2100, it would be 41.2%.
As of 2020, it is 58.2%.
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Now, you tell me, in 80 years of technological progress and economic development, do you think China will be able to become 40% more productive? And manage to do ~the same amount of work with 30% fewer workers?
(PS. China's per-capita GDP grew 40 times in the past 40 years. It's full of smart people, I think it's going to figure something out.)
> And worrying about 'what will happen if human population actually drops to zero' is like worrying about commuter traffic congestion on Mars.
Why not? I don't think it will happen, but at the same time, I don't want to say anything about human behaviour without stating assumptions. If you think (as do I) that there is always some point above zero population at which birth rates do stabilise, then it's valuable to examine what exactly that would entail.
It sounds like we agree the point exists somewhere - we could extend your example to the whole Earth's population becoming 2 and the population becoming (8 bn / 2)% more productive. Why can't we extend it to the population becoming 1?
Because fertility has feedback loops. When there are two people left on earth, their decision to have children or not will not be based on any of the economic or social concerns that we currently face.
It's a completely different situation, and none of the shit we are arguing about applies to it. There's a fundamental difference between running and meeting the long-term needs of a human society of 10 billion people and a human society of 10.
The mathematics you're using is the same reduction to absurdity that leads a manager to believe that nine women can deliver one baby in one month.
And worrying about 'what will happen if human population actually drops to zero' is like worrying about commuter traffic congestion on Mars.
Even in a worst-case projection scenario, like, say, China (Currently at 1.16 births/woman) in 2070:
https://www.populationpyramid.net/china/2070/
43.7% of the population is still working age (25-65).
And in 2100, it would be 41.2%.
As of 2020, it is 58.2%.
---
Now, you tell me, in 80 years of technological progress and economic development, do you think China will be able to become 40% more productive? And manage to do ~the same amount of work with 30% fewer workers?
(PS. China's per-capita GDP grew 40 times in the past 40 years. It's full of smart people, I think it's going to figure something out.)