But, equally, humor can be reactionary and put to demagogic purposes. “Laughter can be … an essential element in mob conduct and is part of the background noise of taunting and jeering at lynchings and executions. Very often, crowds or audiences will laugh complicitly or slavishly, just to show they ‘see’ the joke and are all together.” This is Hitchens again, making the essential point that humor often appeals to rank prejudice and herd instinct.

Humor also has an intimate and unsettling relationship to violence, because violence can be funny. People don’t like to admit this, because it undermines their self-proclaimed civilized values and sense of decency, but its truth can scarcely be doubted. Consider, for example, the notorious ear-cutting scene in Quentin Tarantino’s Reservoir Dogs. Having taken a cop hostage after a bungled robbery at a jewelry store, Mr. Blonde informs his captive that he will now torture him, “not to get information,” but because “it’s amusing to me, to torture a cop.” Sadistic violence—violence for its own sake or for the sake of pleasure—is a terrifying prospect for most people. But before the wet stuff, there will be fun. Mr. Blonde turns on the radio, out of which blasts Stealers Wheel’s “Stuck in the Middle With You.” He starts to dance, performing a show for his hostage—and for us, the enraptured audience. Then the violence starts, culminating with Mr. Blonde speaking into the cop’s severed ear: “Was that as good for you as it was for me?” The first time I watched this scene was in a crowded movie theater in Cambridge, and I remember the whole audience—packed with earnest and upstanding undergraduates—breaking into riotous laughter. And there was nothing slavish about it.

Death can be funny as well. Consider this harrowing recollection by former U.S. Marine William Broyles of the dead soldier he encountered during his service in Vietnam:

After one ambush my men brought back the body of a North Vietnamese soldier. I later found the dead man propped against some C-ration boxes; he had on sunglasses, and a Playboy magazine lay open in his lap; a cigarette dangled jauntily from his mouth, and on his head was perched a large and perfectly formed piece of shit. I pretended to be outraged, since desecrating bodies was frowned on as un-American and counterproductive. But it wasn’t outrage I felt. I kept my officer’s face on, but inside I was ... laughing. I laughed—I believe now—in part because of some subconscious appreciation of this obscene linkage of sex and excrement and death; and in part because of the exultant realization that he—whoever he had been—was dead and I—special, unique me—was alive. He was my brother, but I knew him not. The line between life and death is gossamer thin; there is joy, true joy, in being alive when so many around you are not. And from the joy of being alive in death’s presence to the joy of causing death is, unfortunately, not that great a step.

I recently wrote and abandoned a short satirical piece on ISIS’s savagery. It centered on the testimony of Majid, a disgruntled former member of Al Hayat, ISIS’s media arm, who had been sidelined due to his extremism. He’d won accolades for his proposal to film ISIS fighters raping captive women (even though the men were unable to perform sexually on camera), but his brothers-in-arms had recoiled at his proposal to dangle prisoners over a shark tank.