On July 7, an open letter signed by 153 writers, artists, and public intellectuals appeared in Harper’s. Arguing that a growing “vogue for public shaming and ostracism” has led to “greater risk aversion” among those who “fear for their livelihoods if they depart from the consensus, or even lack sufficient zeal in agreement,” the letter affirmed the value of the “free exchange of information of ideas, the lifeblood of a liberal society.” I spoke with Thomas Chatterton Williams, one of the originators of the letter, about its genesis, the varied reactions it has provoked, and the importance of principles that transcend partisanship.

Ash Carter: You’ve written about these issues for some time now. Why an open letter?