I may not have explicitly stated it in the parent comment, but it's quite explicit other places.

Either a system is sustainable or it's not. If it is, it can continue forever. And, if it's not, it won't. One way or another, it won't, though you can pick the method early on, and later, reality will force it on you. The history of civilization collapse is the history of this reality being forced on groups of people who thought it didn't apply to them.

Plastics in their current form won't exist as new products in 1000 years (though the current stuff probably won't have broken down entirely). Either something far less vile and toxic to "all life" will have been found, or, more likely, industrial civilization will have done the usual "overshoot and collapse" thing, so we won't have the technology to make them in their current form then.

None of that changes the fact that plastic are toxic to life now - and, so, we ought not be using nearly as much of them. I don't mind "durable plastics" quite as much, but the bulk of it is single use, and splitting out all our recycling, I'm regularly reminded of just how much plastic one cannot avoid, even when trying to minimize it.

If the reality (which it probably is...) is that people won't stop doing anything until the external reality we live in forces their hand, the outcomes are almost always far worse than if we decide to stop doing those things earlier.

Plastics are convenient, certainly. They're also a horrid biotoxin that has, quite literally, blanketed the planet in the form of microplastics. We have no idea what to do with the stuff, and burying it only works for so long (and if you're really careful to not let the bits and pieces leech into groundwater). But, I mean, at least you can get water without having to use a drinking fountain!

Plastics aren’t a system. Some plastics are likely to be manufactured in 100,000 years simply because their made from abundant atoms, non toxic, and have useful properties. The current global economy on the other hand isn’t stable across months let alone hundreds of years. But that doesn’t matter much, the meat your eating today probably didn’t come from a wild animal like the meat your ancestors where eating 100,000 years ago but it’s still edible. Different systems to produce essentially the same thing across vast stretches of time.

> Either a system is sustainable or it's not. If it is, it can continue forever. And, if it's not, it won't. One way or another, it won't, though you can pick the method early on, and later, reality will force it on you.

The mistake you are making is thinking the plastic system is a closed system. It is not. The plastic system is part of the universe, which is populated by people who constantly create new knowledge to solve problems. And we never know which new knowledge will be created which will affect this system.

For example, when nuclear power was invented one might have predicted that cheap, clean power would be available to all. But you probably wouldn’t have predicted the environmentalist backlash to it and resultant continued dependence on fossil fuels.

Or Malthus predicting worldwide food shortages and starvation as the population grew. He had no way of predicting the invention of fertilizer.

There are a million examples of this but the takeaway is: people solve problems and create new knowledge that is constantly redefining what is possible.

> The history of civilization collapse is the history of this reality being forced on groups of people who thought it didn't apply to them.

On the contrary, the history of civilization collapse is rife with people who insisted on thinking about things as closed systems and stifling open ended progress (e.g. ancient Sparta).

It is actually hard to think of an example of a civilization which couldn’t have been saved if only they had the right knowledge. Say the cure for a disease or a piece of military technology.

I believe that is the point the other person is trying to make. That humans continually solve problems, create new ones, and rapid progress means a higher likelihood of developing the new solutions needed.