IN the twenty-five years since the fall of the Berlin Wall, the architecture of liberal modernity has looked relatively stable. Not flawless or wonderful or ideal, to be sure; not free of discontents and decadence. But it’s been hard to imagine the basic liberal democratic capitalist order cracking up, let alone envision what might take its place.

Through the dot-com bust, 9/11, the Iraq war, and the financial crisis, it was striking how consensus held, how elites kept circulating, how quickly populist movements collapsed or were co-opted, how Washington and Brussels consolidated power even when their projects failed. No new ideological movement, whether radical or reactionary, emerged to offer the alternative to liberalism that fascism and Marxism and throne-and-altar traditionalism once supplied. And no external adversary, whether Putinist or Islamist or Chinese, seemed to offer a better way than ours.

Here in the dying days of 2015, though, something seems to have shifted. For the first time in a generation, the theme of this year was the liberal order’s vulnerability, not its resilience. 2015 was a memento mori moment for our institutions — a year of cracks in the system, of crumbling firewalls, of reminders that all orders pass away.

This was especially true in Europe, where for generations the parties of the center have maintained a successful quarantine against movements that threatened their dream of continental integration — be they far-right or far-left, nationalist or separatist.