I think the parent's ultimate point is that no country (by which I mean under the same constitution, monetary system, or de facto political arrangement) has lasted longer than a few hundred years.

Even if everything seems economically fine right now and for the foreseeable future, at some point all countries and their associated economies go away and are replaced by something else entirely, at which point the stock market index within said structure goes to at or near zero.

You just need to take a longer time horizon than "when I retire".

What is the scientific basis by which we can expect this to continue indefinitely? In fact, all evidence points to the contrary.

I saw this data on how fast China's economy had grown recently and thought it relevant: https://en.wikipedia.org/wiki/Historical_GDP_of_China

What evidence is contrary?

I do imagine this growth will be asymptotic though on a longer timespan as we need to slow down population growth due to the environmental impact. But who knows? At some point maybe we will be mining asteroids and finding wealth (and places to spend it) outside of Earth.

So the population growth rate of the U.S. is declining, and many developed nations now have negative population growth rate.

> I do see that some nation economies will be hurt and others helped as everything will probably revert to a mean to some degree.

Right, so would you expect the U.S. economy to be helped or hurt by the decline of its economic dominance and a reversion to the mean?

> What evidence is contrary?

No nation, empire, or civilization in history has managed to sustain global economic dominance indefinitely.

There are probably many events that could cause the U.S. economy to contract. But even if the U.S. economy continues to grow, though at a much slower pace than competitors or the global economy, I just don't expect the U.S. markets to continue rising in a meaningful way. People in this thread are claiming that local markets always rise as though they're stating a law of physics, and it's absurd.

The US stock market is made up of mostly multi-national companies. Its a financial center for earth, not an isolated economy.

If we talk about civilization at this point in time then its the global civilization of earth we are talking about.

This is true currently. But again, there's no reason to assume this will continue forever.

> If we talk about civilization at this point in time then its the global civilization of earth we are talking about.

Nice idea, but I'm unconvinced. What does "the global civilization of earth" even mean? The world always seems more connected than the day before. Of course, in 1914 it seemed more connected than ever before. In 1939 too. Yet our global civilization split apart at the seams and we were thrown into two of the most devastating wars ever. And both hugely impacted the economies of the nations involved. The U.S. has been at war almost continuously for the last 25 years. With whom? The global civilization of Earth?

Even if you restrict your perspective to purely economic matters, to a "global economy," this seems dubious. If we truly have a global economy, it's one disproportionately controlled by a single nation -- a situation many nations are probably unsatisfied with, but currently unable to change.

So you've reached the conclusion that other nations are now content to sit back and let the U.S. run the global economy forever. Where's the evidence? Just because no other country has been able to challenge the U.S.'s dominance over the world economy in the past 50 years, doesn't mean they've accepted this as the natural state of affairs.

Yes, that was the basis of my analogy. I do indeed think those situations are similar for that reason.

> But a long term downward trend in the stock market? Means death for a nation's economy.

Well, you're forgetting the idea of a steady-state stable non-growing non-shrinking economy, which is one possibility (see spain: https://www.google.com/finance?q=MADX%3AIND&ei=p5LcVYr0EI6S2...)

But even talking about down-trends, I think "death" is a bit strong. It could also indicate a gradual transition to a lower stable position. Plenty of economies survive at small sizes.