What is your proof that it will not decline further? If you have no proof, then at the very least the cause must be investigated. After all, the concern is that the current rate of declining birth rate, means extinction in a few centuries.

You don't just shrug that off and say "oh well, it'll probably be just fine."

Sure I do. You have zero proof that decline goes below a world population of 1 billion. This belief that it must always grow is based on just a fear. Very similar to the fear that gays marrying will cause everyone else to stop. Hasn't happened.

the only reason for population growth is that economy (asset valuation) is based on future projection of consumption (which is based on population) and social security, which is based on future taxpayer paychecks.

the idea behind "population growth" is that we will need future slaves to prop up our social security and asset bubbles.

think of a country as an ant colony, what happens if population decreases? the queen will get less food

I wasn’t as clear as I should have been: I am not talking about global population and humans going to zero in some hyperbolic nightmare fantasy. I am talking about one society, e.g. US population, living with the values and freedoms and technology we enjoy today, sustaining itself. Our society will cease to exist because of course humans aren’t just going to stop making babies. It’s just that the ones that do achieve positive replacement rate will have different society than us. The call to action is that if we want our comfortable society to persist, we have to swing back to a positive replacement rate at some point time (preferably before we become an irrelevant global minority), and also figure out how to insulate against the other faster growing societies, eventually. I never argued we always have to go up, that only matters in the context of ways to combat other more rapidly growing populations.

We don't just shrug off the fantasy that there will be zero children born in "a couple of centuries"??

What on earth am I reading?

> We don't just shrug off the fantasy that there will be zero children born in "a couple of centuries"??

That's not a fantasy, it's the inevitable outcome of sub-replacement fertility, which is the state we find ourselves in (though my intuition says it will take longer than "a couple of centuries" to get to zero).

It's the inevitable outcome of everybody continuing it for all the generations that remain. As soon as there aren't enough people to manufacture contraceptives, it will of course grow. But after a few generations, there will be more land, water, animal and plant life, copper, cobalt, gold and such per person, and people can easily say "that shrinkage sucked, let's grow". You assume that things will always be the way they are now, which is of course false.

Yes. We’re saying that shrinkage sucked and it’s time to grow. It’s sooner than you’d imagined, perhaps.

....assuming the sub-replacement rate continues forever, which is a hefty assumption. It's quite certain that a greater-than-replacement rate can't continue forever (eventually, the mass of the humans would be greater than the mass of the planet), though that has been the world we've lived in up to now.

You should play a game of Age of Empires, and have your Villager population halved at some point of the game. See what happens then.

We do. Because as you said it's a fantasy.

There are subpopulations with high birth rates. They are very small currently, but if you really think the general population will die off for want of reproduction, eventually they will comprise a sufficiently large fraction of the population to raise the overall birth rate.

The plane only levels off by taking the fact that it has no power to its engines seriously, troubleshooting, and then restoring power. That’s all I’m suggesting we start to do.