In his 2015 book, “So You’ve Been Publicly Shamed,” Jon Ronson explored the effects of internet mobbing, including the story of a woman whose ironic tweet about white privilege went terribly wrong, generating tens of thousands of angry tweets, leading her to lose her job and go into hiding. Since then, the mob has been busy: its focus has turned to a dentist who killed a lion, a series of white women who without apparent cause called the police on black people, a left-wing professor who asked her friends to expel a journalist from a protest, and many many others.

When we think of the savagery of social media, we often think of awful individual behavior — death threats and rape threats; the release of personal information, including home addresses and the locations of the victim’s children; vicious lies; and the like. Harmless Torturers never go that far; we just like, retweet and add the occasional clever remark. But there are millions of us, and we’re all turning the dial.

Parfit never tells us what motivates the torturers in his thought experiment, but there are a lot of considerations in everyday life. We are moral animals, after all. There is abundant evidence from laboratory studies and from real life that we wish to see immoral agents get their comeuppance. And this is grounded in sound evolutionary logic: If we weren’t disposed to punish or exclude bad actors, there would be no cost to being a bad actor, and cooperative societies couldn’t get off the ground.

There is also a sort of social credit that comes with being seen as a moralistic punisher; we want to show off our goodness to others, to signal our virtue. We are more likely to punish when others are watching, and there is evidence that third parties think more highly of — and are more likely to later trust — those who punish bad actors versus those who sit back and do nothing.

Moral and social motivations are hard to disentangle in the real world. When a philosopher — Bryan W. Van Norden, writing for The Stone — says, “Like most Americans, I spontaneously cheered when I saw the white nationalist Richard Spencer punched in the face during an interview,” it is hard to tell how much of this is a report of genuine pleasure at a racist getting his just deserts and how much of it is the desire to be seen as anti-racist to an approving audience. If the conscious motivation for our condemnation is mostly signaling, the idea of making our victims suffer might never even occur to us. And the ease with which we can express moral outrage online — in most cases without any real world repercussions — makes this condemnation that much easier. As our Yale colleague Molly Crockett put it in an article recently, “If moral outrage is a fire, is the internet like gasoline?”