John Etchemendy was the Provost of Stanford University for more than 16 years and has a PhD in Philosophy. He stepped down from Provost role in January 2017. He recently gave a speech to the Stanford Board of Trustees:

Over the years, I have watched a growing intolerance at universities in this country – not intolerance along racial or ethnic or gender lines – there, we have made laudable progress. Rather, a kind of intellectual intolerance, a political one-sidedness, that is the antithesis of what universities should stand for. It manifests itself in many ways: in the intellectual monocultures that have taken over certain disciplines; in the demands to disinvite speakers and outlaw groups whose views we find offensive; in constant calls for the university itself to take political stands. We decry certain news outlets as echo chambers, while we fail to notice the echo chamber we’ve built around ourselves.

This results in a kind of intellectual blindness that will, in the long run, be more damaging to universities than cuts in federal funding or ill-conceived constraints on immigration. It will be more damaging because we won’t even see it: We will write off those with opposing views as evil or ignorant or stupid, rather than as interlocutors worthy of consideration. We succumb to the all-purpose ad hominem because it is easier and more comforting than rational argument. But when we do, we abandon what is great about this institution we serve.

Etchemendy was talking about Stanford, but his words ring true in a broader context. In the long term, intellectual monoculture is the single greatest threat to the American way of life. Our nation was forged by hard work and diversity of people and ideas. As we lose tolerance and receptivity to ideas and views different to our own, we lose the spine and sinew that hold us together.