A constant stream of young workers is required for a sustainable economy.

In order to pay for pensions, the government borrows money from young, working adults. This is effectively what happens in pay-as-you-go public pension systems (which is most of them, to my knowledge, apart from the US, I'm not 100% sure how pensions work in the US). The money you put in actually goes to pay for another person, with the government guaranteeing that they will do the same for you.

If the percentage of retired people increases, the percentage of working adults naturally decreases. Eventually, you'll hit a turning point where the government can no longer borrow from working adults. The government is now in a debt crisis and has to loan money from banks or foreign investors at a significantly higher interest rate, which becomes even more unsustainable if the percentage of retired people increases even more.

This is what is happening in e.g. South Korea and Japan. There are too many old people, and too few working adults. This is caused ny low birth rates over a long period of time.

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ryandrake 2 hours ago | parent [-]

It's going to be painful, but at some point the bandaid has to be ripped off. This idea of sustaining our economic system infinitely through simply breeding more bodies is going to naturally fall apart in a world with non-infinite resources.

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traderj0e 2 hours ago | parent [-]

They don't need the population to increase, just stay the same or not decrease too fast.

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regenschutz an hour ago | parent [-]

Or like the US solves it, through immigration. In the US, the fertility rate is at roughly 1.6 children per woman (which is below the 2.1 children per woman required for a stable population), and yet the US population is steadily increasing thanks to immigration. One can talk all day about pros and cons of immigration, but it is ultimately the only solution we have to a falling fertility rate (other than trying to increase it, of course).

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Qem an hour ago | parent [-]

Fertility in the migrant source areas is decreasing fast as well. At some point the books won't balance anymore, to provide a reliable flow of workers.

	▲	ryandrake 17 minutes ago \| parent [-]
		Yea, my comment was looking at it from a global point of view. We simply can't base the global economy on an infinitely growing population--it's ultimately a ponzi scheme.