[vlovich123]

The person making the claim gets to present the data supporting it.

It depends on what you mean by collapse. Is it that population will decline globally for a bit to a new equilibrium point? Sure I can believe that because boomers were a huge population bubble after WWII and there have been lots of living standard advancements since then (a huge one being family planning options being more and more available to the world’s population). It’s also important to remember that the population bubble was also driven by significant life extension and health advancements in medicine and nutrition without any real birth control being available so the lag until birth control became available results in another population bubble.

None of that is particularly dire. And btw, it’s not even clear to me that the population will actually start decreasing. And even if it does, believing it’s some runaway effect that can’t be fixed within 20 years once we notice it seems myopic as well.

The position you’re taking though, that population will not only decline but that there’s no bottom to it and society will collapse, is the Elon Musk doomer talking point that this somehow portends the end of countries or civilizations or humanity itself. There’s simply no evidence and no realistic mechanism of action for something that extreme. Human populations have always ebbed and flowed and the exponential growth we’ve seen since the Industrial Revolution is not the norm nor is it sustainable.

> This is not a fringe theory. The effects of the collapse we can theorise on, but the collapse will happen now. It's not a question or a theory

Again - you’ve stated something quite extreme without providing any support and then tried to shift the responsibility for providing evidence to the person doubting your wild claim. That’s not how it works, sorry. It is a hypothesis that there’s demographic collapse until it’s either happened or there’s credible evidence it will happen. Right now afaik neither is true.

[zpeti]

The reason this isn't a doomer Elon Musk theory is that the numbers are very counter intuitive. Add to this the fact that our average age is also rising, hiding the worrying signs even more.

Imagine we have a society with 100 people with a fertility rate of 1, that give birth at 20 and die at 80. Here is how that looks:

---

Year 0: 100 newborns (Population is actually 300 at this point)

Year 20: 100 twenties, 50 newborns

Year 40: 100 forties, 50 twenties, 25 newborns Year 60: 100 sixties, 50 forties, 25 twenties, 12 newborns

Year 80: 50 sixties, 25 forties, 12 twenties, 6 newborns

Year 100: 25 sixties, 12 forties, 6 twenties, 3 newborns

Year 120: 12 sixties, 6 forties, 3 twenties, 1 newborn

within 120 years you've gone from 300 people to 22 people

Korea is worse than this. Japan is close, Europe is getting close. A birth rate of 1 is not impossible worldwide soon.

[vlovich123]

In what world do you imagine a constant fertility rate over a 120 year period? In the 1950s everyone was concerned about overpopulation because it was so high. Now you’re concerned about a collapse because it’s low. It’s a silly fear because it’s a control system with a feedback loop. We’re just not used to seeing it oscillate because we’ve been in exponential growth for a long time, but exponential in nature must plateau and that’s what you’re seeing here.

Also you focus on individual countries and yet worldwide the population keeps increasing.

[zpeti]

You are making a big assumption about it being cyclical. Never in history have we had contraception, it's a huge change to human behaviour. It's not at all obvious that women actually want more than 1.5 children on average in the west.

We also have tinder etc and a bunch of other changes that are HUGE in terms of culture.

I'm not saying any of these are bad, and there's not way we are going back to no contraceptives. But to ignore the effects of these, ESPECIALLY as birth rates are trending down EVERYWHERE, is pushing your head in the sand.

You are making a lot of assumptions, and as my example shows, if your assumptions are wrong for say ~50 years, you've already made a huge dent in your populations makeup.