Universities have always been a home for the world’s great arguments. Professors and students are supposed to debate the issues of the moment, gaining understanding of the other side’s views, refining and strengthening their positions, and learning how to solve problems. Argument thrives in a culture of openness, and maintaining that culture ought to be paramount for universities, as well as any institution that wants to shape public policy or debate.

There are many ways to stifle a culture of openness; in recent years, both the far left and the far right have shown a willingness to win arguments by silencing the other side. But the threat that Americans should be most concerned about is any attempt by government to limit the freedom of individuals to express their views or to dictate what they say.

That is what happened when Nathan Thrall, a writer on Israeli-Palestinian issues, was invited by the University of Arkansas to speak on the subject last year, and an ideological barrier imposed by the state government prevented him from joining that debate. Mr. Thrall, like everyone else who enters a business relationship to an arm of the Arkansas government, was required by state law, as stipulated by the contract for his speaking fee, to sign a pledge that he would not boycott Israel. He refused to do so, calling the requirement “McCarthyist” and an affront to his free-speech rights.

This meant that he was unable to share his perspective, informed by years of experience writing about the relationship between Israelis and Palestinians, at a time when students have a desperate need to understand the causes and effects of the war between Israel and Hamas in Gaza. The campus has lost many other speakers for the same reason, and students say they are missing out on the chance to hear a variety of voices.