As campus clashes over free speech and race go, last week’s dust-up at Dartmouth seems to have been a relatively tame affair. But staff writer Rob Wolfe’s account serves as a reminder that these skirmishes actually do harm the cause of free expression and academic freedom, even — or perhaps especially — among non-combatants.

The incident itself began with the posting by a student group known as Dartmouth College Republicans of a bulletin-board display in the Collis Center honoring police officers killed in the line of duty. The display appeared under the provocative title “Blue Lives Matter,” which elicited the probably-hoped-for response from Black Lives Matter activists, who were apparently unable to resist the temptation to take down the display and replace it with fliers bearing a message of their own regarding police violence against civilians.

The young Republicans professed to be shocked — just shocked! — at this affront to their right to express themselves, and issued a statement claiming to be “dismayed that a group of students would attempt to censor our message while co-opting the space for their own purposes.”

President Phil Hanlon duly delivered the obligatory condemnation of “an unacceptable violation of freedom of expression on our campus,” and the administration promised to round up the usual suspects to see if any disciplinary action was warranted. (Wolfe reported in this context that the college had found no violations of its Standards of Conduct in relation to last fall’s protest by Black Lives activists in Baker-Berry Library, which by most accounts seems to have been significantly more intense than last week’s indirect confrontation.)

We’re generally inclined to regard the bulletin-board war as an exercise in immaturity on both sides. But as in actual battle, there was collateral damage. Several days after the incident, Wolfe interviewed two students having lunch in Collis under the shadow of the offending (or offended) bulletin board. One, a junior, sensibly took exception to both the tone of the Republicans’ display and the activists ill-advised decision to remove it. More tellingly, both expressed reticence about speaking to a reporter and indicated that because of the climate on campus, they felt they needed to be careful in their discussions with other students. “I think to an extent you can talk to people of opposing viewpoints,” said one, “but I wish I could talk more freely with people.” The other agreed: “You do want to tread lightly.”

It hardly needs to be said that if this hesitance to speak one’s mind is widely shared on campus, then the whole idea of a liberal education is called into question. The marketplace of ideas depends on the uninhibited exchange of views, nowhere more so than in academia. This is true not only of the sellers — those committed to strong opinions on either side of a question — but also of the consumers who sort through those views with an eye toward buying in. College students ought not to feel the need to tread lightly, but to go boldly where they haven’t gone before. That’s how young people discover themselves, and how society’s institutions are renewed.