Nothing in history is inevitable. But it sure looks like the politically centrist neoliberal order that held sway throughout large swaths of the world over the past two-and-a-half decades may well be doomed.

As recently as the middle of 2017, analysts thought the populist challenge to the centrist establishment would be turned back following the Brexit vote in the U.K. and President Trump's shocking victory in the United States. Surely the electoral defeat of populists in France and the Netherlands, along with Angela Merkel's buoyant poll numbers heading into a national election in Germany, were cause to suspect precisely such a rethinking on the part of voters. Yes, they were angry, but now they'd seen the alarming consequences of acting on their destructive impulses and come to their collective senses.

The latest sign that this was wishful thinking comes from Italy, where in a national election this past weekend the governing center-left Democratic Party finished a distant second (with roughly 19 percent of the vote) to the upstart Five Star Movement of left-leaning populism (which won 32 percent). Meanwhile, coming in just behind the establishment center-left was the far right (The League, with approximately 18 percent) and paleo-populist Silvio Berlusconi's center-right Forza Italia (with just under 14 percent). Forming a government from this mishmash of competing populisms will be extremely difficult, since the parties share little besides an antipathy to the ruling political establishment in Rome and Brussels.

Germany might be just one election from a similar fate. After several months of stop-start negotiations, members of the center-left Social Democratic Party voted over the weekend to join in a national unity government with Merkel's center-right Christian Democrats. It's the same coalition that governed the country prior to the most recent election in September — only now both centrist parties are substantially weaker than they were, with the newly formed far-right Alternative for Germany (AfD) the largest opposition party in the country.

This time around the parties of the centrist establishment refused to entertain forming a government with AfD. But if their share of the vote falls much lower, and/or if AfD gains further ground between now and the next election, that may prove impossible — or else require the formation of a fragile and ideologically incoherent government among the remaining parties.

If the situation in Germany and Italy shows that the rise of anti-system parties can lead to ideological incoherence and practical dysfunction, trends in Hungary, Poland, Austria, and the Czech Republic have shown that when populist impulses coalesce on one side of the political spectrum (in all of those cases, on the right), the act of challenging the centrist consensus need not produce political debility. Whether the European Union proves capable of governing itself, or even staying intact, with growing numbers of its member states opting to shift their politics several clicks to the nationalist right is another matter.

But the populist insurgency isn't limited to Europe. In Mexico, Brazil, and Indonesia, upcoming elections could catapult anti-establishment parties and politicians to power. The same is true in Great Britain, where the Labor Party led by the far-left Jeremy Corbyn appears poised to take control of parliament in the country's next election.

And then there is the American populism of Donald Trump.

Because American politics (like the continent-wide country itself) is so big and noisy, it's tempting for domestic observers to view Trump as sui generis — as an outgrowth of very old, morally pernicious impulses in the conservative movement and Republican Party. While it can be useful to highlight such long-term domestic continuities, it's also important to recognize present-day links between the rise of Trump and his analogues abroad. When we do so, the Trumpification of the GOP begins to look a lot like the rise of far-right populist parties abroad, albeit from within the country's established center-right party. The same thing happened in 2016 with the left-wing populist insurgency of Bernie Sanders within the Democratic Party.

If the U.S. had a multi-party system, we'd be seeing the same kind electoral collapse in the country's centrist parties and rise of populist parties of the right and left that we've witnessed in Italy and Germany. But because our electoral system so strongly favors two parties, this shift is happening internally to the Republicans and Democrats. A generation or more from now, our parties will probably have the same names and trace their histories back to the same heroes of the past, but their ideological configurations will probably be very different than what they were during the decades immediately following the end of the Cold War.

The transformation of the GOP into a right-wing populist party is already well underway. Partly in response, the Democrats are following suit by shifting further left. Not that either change is happening without a fight. On the contrary, just as the formation of a stable and coherent government in a multi-party system becomes more difficult when parties further removed from the center gain in strength, so the big-tent parties that prevail in two-party systems begin to buckle as those on the inside drift apart ideologically from one another. But of course the gap separating members of the same party is nowhere near as wide as the even greater chasm that separates each party from the other.

Those are the centrifugal forces that will be buffeting our political system for the foreseeable future — with each party lurching away from the center and engaging in a rancorous internal struggle over how far to take the change. What happens if Trump's massive tax breaks for corporations, cuts to federal regulations, and attacks on immigration are followed by Democratic moves to vastly expand social programs, increase taxes, and open the nation to newcomers? The answer is that those very policies, which gained popularity on the left partly in reaction to Trump's diametrically opposite agenda, will provoke yet another round of radicalization on the right, and so on and so forth.

Politics in a polarized, populist age can be nasty, turbulent, and unstable. But it will never be boring.