At the Rally to Restore Sanity in 2010, Jon Stewart delivered a funny political speech to a crowd of his fans on the mall in Washington, D.C. He praised reasonableness, compromise and the virtue of working together with our opponents. Insanity however proved resilient. Last month, he told an audience that it was an error to mistake cultural power for real power, adding: “I, being a part of that machine and mechanism, do feel oddly culpable.”

For Mr. Stewart, who more than anyone elevated the political stature of the late-night talk show, to make such a concession is jarring. But it fits the mood right now, one defined not by the army of his television successors but by the Australian stand-up Hannah Gadsby. Her ferocious special “Nanette” tapped into a growing cultural anxiety about the limits of comedy. She skewered the nature of jokes, arguing that because they inevitably lead to incomplete stories, they evade difficult truths.

[Hannah Gadsby on the toll of performing “Nanette.”]

The media gravitated to her bracingly categorical argument. Slate announced that “Nanette” was evidence that comedy was “broken,” and a Vulture review concluded from her argument that jokes “can’t really challenge or change anything — and are therefore more conservative than progressive.” Such critiques are just as common in the conservative media. Reviewing Sacha Baron Cohen’s new series, “Who Is America?,” a critic for The Federalist lamented, “Comedy is supposed to connect us as humans. Now it’s tearing us apart.”

When did comedy become the worst medicine?

It is a relatively new development. Until recently, comedy had been rapidly expanding, increasingly co-opting areas of our culture previously dominated by sober voices. One of the most memorable responses to the Sept. 11 attacks was David Letterman’s emotional on-air speech processing his grief, which set a precedent for talk-show hosts offering healing words after national tragedies. Corporations and business schools now regularly hire troupes like Second City to teach them how the principles of improv can help their bottom line.