Making an unpopular decision and accepting the ensuing criticism is part of the job of a university leader. Whether the topic is research priorities, academic freedom, athletics, or, as it turns out, snow days, there is always a range of opinion on a college campus. And there should be, provided the campus nurtures an environment where everyone feels safe entering into the debate.

When those opinions move from civil and respectful discourse into vitriolic attacks on an individual it can be discouraging and damaging – personally and institutionally. On Monday, about a dozen students, upset that classes were not canceled because of cold weather, took to social media to criticize the decision and to attack me – in comments that were vulgar, crude and in some instances racist and sexist.

People have asked me whether the attacks disturbed me.

Yes.

Not necessarily on a personal level, because many of the comments could be dismissed as juvenile, notwithstanding the offensive language.

Not because the comments truly reflect my university. The outpouring of support from our students, my colleagues and others – including heartfelt apologies from several of those who posted comments – has shown our true nature.

What was most disturbing was witnessing social media drive a discussion quickly into the abyss of hateful comments and even threats of violence. I shudder to think what might happen if that type of vitriol were directed at a vulnerable member of our student body or university community.

The negative comments, as offensive as they were, are protected speech. But what is protected expression and what is the level of discourse we as educators expect from our students can be very different things. And the size of that gap – so evident this week – is what has been most disappointing. Racist, intimidating or culturally derogatory epithets have no place in any debate in any circumstance. Of all places, a university should be home to diverse ideas and differing perspectives, where robust – and even intense – debate and disagreement are welcomed.

How do we foster such an atmosphere? Only through an unwavering and unrelenting commitment to building truly diverse communities of students and scholars. One dinner with someone who doesn’t look like you and doesn’t sound like you can open new worlds of ideas. You can sit in a classroom and discuss situations in Egypt or in Syria based on academic readings. But, to hear these issues explained by a classmate from that country, from her or his personal experience, in his or her voice – this is when an academic exercise can become a moment of personal transformation. That is why we say diversity is the route to excellence.

And, in fact, we are a diverse campus at Illinois, with students, faculty and staff from every state and more than 100 nations. They are a key part of what makes our university special, a community of cultures and ideas that generate original thought, outstanding research and the excitement that comes with working with the top people in their fields. But this incident shows that we still have work to do.

On Monday, Jan. 27, we held classes, as usual, at the University of Illinois. And, I hope, we all learned something.