"Yes, there are these norms that you don't speak ill of the dead," Brubaker said. Those norms are most vigorously enforced in what he called "pedestrian deaths, of people like you or me. (No offence, but I don't think either of us will be lying in state.)"
And those norms hold true, mostly, for virtual cemeteries and online memorials, as when a bereaved family member takes over a Facebook page of the deceased. Or at online obituary sites like Legacy.com, which appeared within the first decade of the internet. Yet even there, Legacy.com had to hire moderators - by 2006 it had nearly 50 - to scrub unkind comments from the site.
And this custom has rotted away completely in darker corners of the internet.
In 2012, one of the few studies of the taboo in the online world described its breakdown at the website MyDeathSpace.
University of Nebraska at Omaha communications professor Paige Toller, an author of the study, said she expected to find a grieving community. Instead, it was a group of self-appointed "death detectives" who combed the social network MySpace for information about people whose lives had ended in suicide.
"It was basically people that, from what we gathered, had no apparent connection with the deceased," she said. They "were writing just very judgmental, negative, hurtful comments."
Toller's co-author, Lynnette Leonard, a professor of journalism and mass communications at the American University in Bulgaria, said that their findings "absolutely apply to communication on Reddit and Twitter."
The most extreme responses on MyDeathSpace, she said, came from the ability to be completely anonymous. "In those conditions, you see some of the worst: 'good thing they are dead' 'they should be dead' 'If they hadn't died someone should kill them' kinds of posts."
For non-pedestrian deaths, internet adherence to the taboo changes, too. Brubaker and his colleagues analysed Facebook comments after deaths of actor Alan Rickman and singers David Bowie and Prince in a 2017 paper.
Beneath news articles posted to Facebook by the New York Times and CNN, tempers flared. Some Facebook users wanted to express their grief. Others wanted to reflect on the life of a public figure.
"You're ending up with people who are talking to each other who don't understand they are in different conversations," he said.
Fans have what communications scientists call parasocial relationships with celebrity. "That doesn't mean the relationship isn't authentic or it isn't real," Brubaker said. It's simply that you feel connected to famous people and they have no idea who you are. When death ends that parasocial relationship, those on the pedestrian end feel grief.
In long-term online communities, norms have time to solidify. After the death of Alan Rickman, members of Harry Potter fanpages knew how to express their mourning and grief by adhering to these norms.
The Facebook comments at the bottom of a CNN article about his death, however, were different. Some people wanted to talk about their personal connection to the way he played Severus Snape. Others wanted a warts-and-all evaluation of his life. In this newly formed morass, people began policing the comments, Brubaker and his colleagues found. They summed the characteristic response: "This is a space for grief, and your speech is not an expression of grief."
When deceased politicians are involved, the comments get really interesting, Brubaker said, referencing unpublished work that examined comments made after the death of Supreme Court Justice Antonin Scalia. "It was just so different," he said, everything from "scum of the Supreme Court" to mourning to prognostications of the country's future.
In 2013, after the death of Margaret Thatcher, media analytics firm Synthesio examined the first wave of 25,000 online comments. It characterised a third as negative. A digital campaign to promote Ding Dong the Witch is Dead sent the song to second place in the UK singles chart. (BBC Radio 1 aired a 5-second clip instead of playing it in full, as is custom.)
"Maybe it is this communication platform that frees people up to say things that they would never say to someone's face," Toller said.
Leonard said that, as she studies online communication, she finds written what we used to say "behind our hands or under our breath." De mortuis nihil nisi bonum is a lovely motto. Perhaps the internet has revealed only our inclination to preach it.
