One of the most important trends likely to drive the 2020 presidential race: A growing disillusion with capitalism as practiced, and a coming struggle over how to recast this pillar of the Western order.

The bottom line: You could hardly challenge a more basic part of who we are as Americans and Westerners.

Polling shows a rising number of young Americans prefer socialism to capitalism.

Gallup found this summer: "Americans aged 18 to 29 are as positive about socialism (51%) as they are about capitalism (45%)."

"Americans aged 18 to 29 are as positive about socialism (51%) as they are about capitalism (45%)." That's "a 12-point decline in young adults' positive views of capitalism in just the past two years and a marked shift since 2010, when 68% viewed it positively."

Why it matters: The main messengers of this coming steamroller are nowhere near the fringe. They're mainstream thinkers with ideas like, "We must rethink the purpose of the corporation" and "The crisis of democratic capitalism" (both from Financial Times columnist Martin Wolf).

The thinking is captured in a clutch of must-read new books by Paul Collier, Jonathan Tepper and Oren Cass; and a growing body of academic papers in the U.S. and Europe.

in a clutch of must-read new books by Paul Collier, Jonathan Tepper and Oren Cass; and a growing body of academic papers in the U.S. and Europe. What they are mostly doing is connecting the dots of what we all realize by now: Flaws in the system — including forgetting about so much of society — are largely to blame for widespread disaffection with establishment institutions, leaders and answers.

The evidence of something profoundly amiss is visible in:

Almost four decades of largely flat wages for the vast majority of workers.

of largely flat wages for the vast majority of workers. Four decades of meager productivity gains.

of meager productivity gains. An anemic number of new startups, and relatively few IPOs.

If you remember one thing: All that bigness that you see around you — outsized cities, companies and individuals gobbling up most of the economic pie — is not normal.

For the economic system to become more inclusive, competitive, and deliver for more people, some or a lot of that bigness may have to be broken up.

Axios' Felix Salmon notes: The past four decades have seen massive global increases in wealth and income and productivity, thanks almost entirely to capitalism. (Look where South Korea was 40 years ago!)

So flattened wages in the U.S. reflects the way the benefits of capitalism wound up getting spread across the globe, rather than being concentrated in the West.

in the U.S. reflects the way the benefits of capitalism wound up getting spread across the globe, rather than being concentrated in the West. This does, of course, explain the disaffection in the West.

What's next: In the U.S., look for this trend to be a primary battleground among Democratic presidential candidates in 2020. Each of the political parties is likely to promise that it can best reformulate the system to deliver for the vast number of Americans.

Axios' Dan Primack points out that this could be the dividing line in the Democratic primary: A pretty hardcore group that believes that even Sen. Elizabeth Warren is too capitalist (because she wants to reform, not replace).

Be smart: Innovative Republican candidates will also reach for many of the same issues and solutions, rather than the GOP orthodoxy of old.