She’s not doing either. In that same conversation, she goes on to talk about how we don’t live in that world and can’t return there, and what the implications should be for policy.
The thing is that if you depopulate by reducing the birth rate, you end up in a situation where you have a whole lot of old people and very few young people, which cannot be sustained.
However, in the intermediate stage, you are desperately short of working-age people to help support the massive aging population.
This isn't a theoretical - most of Western Europe has been in this boat for a long time, and relies heavily on immigration to fill the labour gap (despite however much political posturing about wanting to restrict immigration)
If we do this on a global scale, there is nowhere to draw immigrants from, and a bunch of old folks are going to be abandoned to die...
What's the alternative though? Creating new humans purely to be able to have them work and pay for stuff for other existing humans? That doesn't seem a bit dystopian for you?
The problem I have with this logic is that it seems to assume a binary of the population either staying at least as high as it is or massively reducing. The idea that there's no middle ground where the population goes down slowly rather than massively spiking all at once feels like it needs much more justification rather than just assuming it.
Oh, for sure, that alternative is not great either. We've built a society on the myth that infinite growth is possible, and at some point the chickens are coming home to roost...
I guess the question is just whether we want to be the generation that decides to try to do something about this problem or let it keep going on for a later generation to solve. Either way, we won't be the ones who actually are around when the pain starts to be felt, and it's not like as individuals we can do a whole lot about it anyhow. My wife and I have no interest in having kids, so I guess we're doing as much as we can, although our decision is pretty much completely unrelated to any opinions about population I might have.
Humans are humans, at the end of the day. Especially as someone who grew up at the height of EU open borders, I'm not real bothered which side of an imaginary line on a map someone happened to be born on
If the only argument behind why Europe should exist is that you don't like people who look like the people from Sudan or India, then maybe it shouldn't.
(If you instead want to claim that you're not trying to talk about ethnicity and are instead talking about economies or whatever, consider whether the ancestors you mention drawing those imaginary lines over places like Sudan and India were motivated by their desire to colonize and extract wealth from them at the expense of the local populations, and whether that's more responsible for the economic differences between them and Europe than the lines themselves)
In order to achieve this, though, we desperately need to get every country well below replacement-level fertility rate, and sustain that for a long, long time. Not sure it's possible, particularly when some political factions still consider "below replacement" to be a bad thing.