In a new paper, a senior European Union economist suggests anew that the political upheaval on both sides of the Atlantic could erupt into World War III, a danger that numerous scholars and politicians have flagged for a couple of years.

Details: In his paper, however, Gerhard Hanappi, a professor at the Institute for Mathematical Models in Economics at the Vienna University of Technology, describes how such a war could unfold: Between the U.S., Russia and China; in the form of multiple, small civil wars within countries; between poorer and richer nations of the world.

I emailed a few geopolitical specialists about Hanappi's forecast. Most were scornful — Brookings' Robert Kagan called him "loopy" and Richard Haass of the Council on Foreign Relations said, "I can't see why you would give this that much attention." But all went on to offer their own view of the prospect of war.

Here are excerpts:

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"He’s not really forecasting WWIII. He’s saying global conflict is far more likely given the rise of nationalism/authoritarianism and its disintegrating impact on global capitalism. With that caveat, I agree with him. We’re on a path to far more global violence and deprivation, despite all the breakthroughs to alleviate poverty and advance well being, because the geopolitical order is falling apart. And the tail risks of all three of his global conflict scenarios are increasing accordingly."

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"I certainly do worry that we could be headed for war if we don’t watch out. I don’t believe it is inevitable. But as World War I showed, you can stumble into war — a war which nobody wants. We are still a ways away — somewhere in the 1890s by my estimation. But there is too much lighthearted warmongering. And we seem to believe that China has no business being a global power, rather than accepting that the world won’t be just the U.S.’s oyster forever."

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"To say that capitalism is 'disintegrating' because of the rise of nationalism/authoritarianism is historically dubious. Did capitalism disintegrate when nationalism/authoritarianism were dominant forces between 1800 and 1945? No. It eventually rose to take over the world. Geopolitics is critical to the equation. To say that 'capitalism is disintegrating' is different from saying we are returning to geopolitical competition over spheres of influence and to the historic divide between democracies and authoritarians. And the two together suggest increasing likelihood of conflict, especially if Americans are not interested in deterrence any more."

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"The internal challenges capitalist/developed/democratic countries are facing are real and could threaten social cohesion and our willingness and ability to tackle international challenges. (The) situation [is] worse than it was, which is what you’d expect a guy who wrote a book about disarray to say."

"The odds for something happening somewhere have gone up, but [it's] impossible to predict exactly what and when and impossible to predict how it might unfold."