[turc1656]

I agree that "it should work perpetually so long as a nation doesn't see massive population decline and employment remains reasonably consistent".

But the same thing is true for a ponzi scheme, right? The idea is a never-ending growth from which new people pay the existing. The requirement that the US population must continue to grow - not just stagnate and contain the same number of people, but grow, indicates a ponzi-esque scheme to me. There is a finite amount of resources on the planet. Therefore there is a finite number of people that can be living on this planet. But such systems mathematically require that the number of new people constantly goes up over time. This is indicative of an unsustainable system.

If it were altered in a way such that, for example, there was a 1:1 (payers:recipients) relationship (or less) between the number of payers and the number of recipients, than I'd say that's sustainable because it doesn't require growth. Currently we have ~130M payers and 64M recipients, which means there's a roughly 2:1 ratio. On the surface it looks fine because you think hey people work for 40-45 years and then retire for 20 so 2:1 sounds about right. And it is, but only if you can continue to produce that larger base forever.