Quote Originally Posted by Surferbeetle View Post
(...), a portion of the costs the 60+ cohort has not saved for (or subjected to pension shortfalls).
It makes little to no sense to speak of savings of elderly when looking at demographic problems. My country had this fallacy in its public discourse about the topic a decade ago as well (and sticks with it), but it's still a fallacy in most contexts it's being used in.

Look, the quote is talking about the global population, so there's a perfectly closed economy (as quite safe assumption even for 2050, 2070 etc).
The elderly may have savings or not, but that's merely an indicator for allocation issues. What would they do with their savings? They would buy the period's economic output (or output that's not much older).

It makes thus little sense to discuss savings in the context of demographic change; it's much more reasonable to speak about natural GDP growth paths, capital stock, depreciation rates (share of very durable goods in capital stock) etc.
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My view on demographic change etc is the view of someone who has read too much about history:
Forget about the supposed problem. Humans adapt easily to changes, and especially so to slow changes. The problem almost solves itself because it's so creeping.
We might be able to consume more per capita if a larger share was working. Not going to happen. Instead, we won't get used to this 'more' consumption and thus won't really miss it more than we would miss 'even more' consumption if we had 'more'. We won't be satisfied anyway.

When thinking about this topic I contrast the often qualitative answers provided by economics with the quantitative answers provided by science & engineering. Although exogenous inputs are an example of a nonlinear stochastic process, IMO economics still has a ways to travel yet before it can provide satisfactory answers to the questions we pose.
Maybe the problem is with the questions.
Very, very, very much can be answered with economic theories older than I am. Most often economic science can say "this would be stupid because ..." and there's no real need to calculate how stupid it would be.

The problem is in my opinion more that people cannot make good use of existing economic theories. It's perfect routine for politicians to ignore economic science advice and listen to charlatans instead.