At Middlebury College, student demonstrators recently shut down a speech by Charles Murray, the conservative writer, in the process injuring a Middlebury professor who was accompanying him.

At Claremont McKenna College, student protesters this month succeeded in shutting down a speech by Heather Mac Donald, another conservative writer. In a subsequent letter, students from the adjoining Pomona College explained that Mac Donald “is a fascist, a white supremacist, a warhawk, a transphobe, a queerphobe, a classist, and ignorant of interlocking systems of domination that produce the lethal conditions under which oppressed peoples are forced to live.”

Officials at the University of California at Berkeley last week canceled a scheduled speech by Ann Coulter, the conservative writer, on the ground that the school could not “find a safe and suitable venue” for her.

Outbursts of campus activism can be good, potentially even great. But far too often, they turn out to be about expressing what students regard as the correct values, rather than actually improving people’s lives. Expressive protests take up a lot of time and energy and produce an abundance of passion. But they do little or nothing to address the injustices students say they want to remedy.

Efforts to shut down speakers are the worst and the most extreme form of campus expressivism. It should go without saying that at colleges and universities, free speech is indispensable, and interferences with it are deplorable.

If the goal is to combat “interlocking systems of domination,” students have opportunities, whether the activity involves helping particular individuals who face terrible conditions, or devoting time and attention to some kind of reform that might produce systemic change. Instead of silencing speakers, how about helping victims of domestic violence or working on behalf of increasing the earned-income tax credit, one of the best programs for combating poverty?

To be sure, most forms of campus expressivism are a lot less harmful than efforts to shut down speakers.

At Princeton, for example, students engaged in a 32-hour protest and sit-in at the office of President Christopher Eisgruber, asking him to excise Woodrow Wilson’s name from its buildings and programs because Wilson believed in racial segregation. But how, concretely, would it further the cause of racial justice if Princeton dropped the name of its former president — and the president of the United States?

No one should deny that symbols matter, because they can affect how people experience their institutions. It is important to reckon with history, and in some cases changing names might make sense, especially if a building was originally named after a prominent defender of slavery.

But far too often, student expressivism looks inward at college life, rather than outward at the world, focusing on what is happening on campus rather than in places where people most need help. It ensures students will devote their limited time, idealism and concern for justice to actions or reforms that do little or nothing to improve human lives.

Previous generations of student activists contributed immeasurably to the civil rights movement and the fight against sex discrimination. On the right, they helped create the Federalist Society, which has transformed how judges and lawyers think about the Constitution. On the left, they have given life to the movement for LGBT rights.

Student activists would do well to think much less about how to express their values and instead to focus insistently on a single question: If I succeed, how many people will I actually be helping?

Cass R. Sunstein is a Bloomberg View columnist.