[shiroiushi]

Fewer people means less insurance in case of natural disaster, less innovation, less of everything really. Of course, that has to be balanced with resource consumption, environmental effects, etc.

Also, a declining population doesn't just mean "go back to a more sustainable level". It's not like people are suddenly going to start having babies again when the population gets to, say, 1B, and things will carry on sustainably. Instead, there'll barely be anyone who can have babies, because everyone will be elderly (i.e. inverted population pyramid), so the population will just keep collapsing. And with so many old people needing care, and no young people around to do it, things are going to get really bad quickly.

People seem to think we're going to invent some super-advanced humanoid care-giving robots "any day now", and I suppose also invent some way of people being able to have more kids over a longer lifespan or something, but betting your society's future on uninvented technology is not good planning I think.

[ElevenLathe]

If we can survive population decline at all (fwiw I think is still an open question on a planetary scale), we shouldn't worry about rebounding for a long time yet. So many problems we face that would be easier to solve at 1B people than 10B would also be even easier with 100M. The "market" will clear and human population long term will settle into something that can be sustained with available resources and biosphere services. Getting there via "attrition" is preferable to getting there via apocalyptic wars, famines, genocides, and diseases.

[shiroiushi]

>Getting there via "attrition" is preferable to getting there via apocalyptic wars, famines, genocides, and diseases.

How do you think wars are going to be avoided when there's a demographic collapse? With so many old people and so few young people to support them, something's going to break. People don't normally just put up with failed economies; wars are a frequent result. Famine is also a strong possibility: the elderly people probably aren't going to be doing all the farming, but they still need to eat.

People who talk about population reduction as a good thing always seem to assume that the demographics will be similar to today, with plenty of young people to balance the old people, and that's absolutely not what's in store.

[ElevenLathe]

Right, hence my parenthetical. If we can do it at all, we should keep going. If we can't, then there's no good outcome available and we only get to choose between demographic collapse or biosphere collapse.