For nearly a century, America has maintained a unique tradition of distinguishing between words and acts: One can say almost whatever they like, and be as offensive as they please, so long as those words aren’t likely to lead to otherwise avoidable physical harm. In 1919, the Supreme Court ruled in Schenck v. United States that, unless words are “of such a nature and used in such circumstances as to create a clear and present danger”—as in falsely yelling “Fire!” in a public place—the First Amendment to the Constitution protects any kind of speech.

John Stuart Mill, the English philosopher and economist, outlined a similar theory of speech six decades before Justice Oliver Wendell Holmes Jr. wrote the opinion in Schenck. In his 1859 treatise, On Liberty, Mill gave the example of a newspaper publishing an opinion article claiming that “corn-dealers are starvers of the poor.” Whether corn dealers are actually starving poor people or not, Mill argued, such an article would have to be permitted because it is expressed within a context in which no immediate harm might be caused to corn dealers. It would not, however, be acceptable to place those same words on a poster or a placard next to a corn dealer’s house, where an angry mob is gathered. Doing so, Mill wrote, would constitute “a positive instigation to some mischievous act.”