In the late 1960s and early '70s, America's college campuses exploded with widespread protests and sometimes-violent unrest.

It's about to happen again. And this time, it might be worse.

The first time around, there were a variety of causes: the civil rights movement and the injustices that inspired it; the perceived immorality of the Vietnam War and the threat of conscription; growing hostility toward the supposed conformity of the ruling establishment (which included the leadership of the nation's universities) and its complicity in the country's multifarious ethical lapses; the rapid, destabilizing rise of youth culture along with its celebration of and demand for anti-bourgeois forms of entertainment (sex, drugs, and rock 'n' roll).

Today the causes and trends look very different, but they are conspiring to produce a very familiar perfect storm.

American political culture is more polarized than it has been in decades, perhaps going as far back as the Civil War. The election of Donald Trump to the presidency was both an expression of this polarization and a provocation for more of it, as we have repeatedly seen in the country at large during the 10-plus months since Trump's shocking electoral victory. That sets the broadest context for rising campus tensions.

More specifically, there is Trump's distinctive style of cultural populism and alt-right conspiracy-mongering, which mocks and even flagrantly assaults (at the level of both policy and political rhetoric) the highest ideals of the university: the methodical pursuit of truth, and respect for all members of the campus community, very much including those from marginalized groups. Most colleges, from world-renowned research universities on down to community colleges serving working-class populations, welcome immigrants and foreigners as students. They also tend to see themselves as contributing to the benefit of humanity through the pursuit and dissemination of knowledge (and consequent vanquishing of ill-informed prejudices). That makes campuses places uniquely inclined to oppose everything Trump and his most vociferous supporters stand for.

Then there are the conservative student groups that deliberately invite right-wing rabblerousers to campuses, not primarily to broaden the range of acceptable topics for public debate (which is an important and admirable goal), but in the hope of provoking an overreaction on the part of left-leaning students and faculty members. This is then made even more volatile by the presence in some communities of "antifa" left-wing extremists who appoint themselves arbiters of acceptable thought and take it upon themselves to mete out violent punishment to those they judge guilty of ideological transgressions. When clashes between these opposed illiberal groups get out of hand, images and stories of angry denunciations and violent actions get repurposed as propaganda in the right-wing media, which promotes them as evidence of generalized lunacy in American higher education.

And that brings us to the final element in the increasingly toxic brew churning on so many campuses — the anxieties of university administrators. Eager to demonstrate their commitment to the open exchange of ideas, but also terrified of how donors, alumni, and parents of current and future students will respond to bad press, administrators often end up in an impossible situation. First they invite to campus, or agree to honor, a controversial speaker (whether on the right or the left). Then some faction on campus that opposes the speaker, or some ideologically antagonistic media outlet, or maybe just a noisy group of partisans on social media, makes a stink. In the echo chamber of our technologically amplified public life, the controversy can grow deafening in a matter of hours, inspiring the very same administrators to capitulate, withdrawing the original invitation — and in the process managing to provoke a whole new round of accusation and recrimination.

We've seen this happen with right-wing speakers (Milo Yiannopoulos and Ann Coulter at the University of California, Berkeley) and, more recently, with figures admired by many on the left (Chelsea Manning at Harvard's Kennedy School, Fr. James Martin at Catholic University). Each time the cycle gets repeated, the antagonistic forces and parties on and around campus dig in further and prepare for the next round of hostility.

No one knows when one of these incidents — or more likely, a precipitating event in Washington or elsewhere — will spark something bigger than a self-contained protest at a single college. But the pressure is building on campuses across the country. They are unlikely to remain placid for very long.