This is a very disappointing comment line. I know not everyone here is a CS major, but if you're even CS-knowledgable you should understand what an exponential process is. It is not, as many laypeople assume, something that is "very big".
That said, I was not intentionally trolling. I do think it's possible for a SS-style benefit to sustain itself provided that an exponentially growing population, whose exponent is greater than 1, is obligated to pay in.
A country with a stagnant or declining population will probably have trouble.
You may disagree, that's fine.
Nevertheless, any population whose growth (or lack of growth) is defined by the average number of children per member will behave exponentially.
