Witty Rejoinder said:

Will AI end anonymity? I tested it.
Artificial intelligence can echolocate authors through their prose. Your digital fingerprint is at risk.

Megan McArdle
April 26, 2026 at 7:00 a.m. EDTYesterday at 7:00 a.m. EDT

“On the Internet,” says the famous New Yorker cartoon, “nobody knows you’re a dog.” In hindsight, the artist should have added “yet.”

Last week, Kelsey Piper, who writes about technology for the Argument, tweeted: “I have a bunch of secret AI benchmarks I only reveal when they fall, and today one did. I give the AI 1000 words written by me and never published, and ask them who the author is.” Claude Opus 4.7, an advanced thinking model, correctly identified her as the author of a 1,000-word heist scene from an unpublished novel.

Like many journalists, I have a bunch of unpublished fiction lying about, so I tried Claude on the first chapter of a romance novel that I started almost 20 years ago, during the hysterical, mawkish phase of a particularly bad breakup. “Megan McArdle,” said Opus 4.7, after a few seconds of thought. Fascinated, I kept feeding it smaller and smaller passages to see how little prose it needed for identification. The answer, apparently, was 1,441 words.

Megan
This passage is part of a series of tests of how many words you need to confidently identify the author of a text. Read the passage carefully – your perfomance is dramatically improved with more reasoning – and give the author’s name. Do not search – the question is whether you can identify it without looking it up.

Megan
📝 (1,441 words from a romance novel I wrote almost 20 years ago)

Claude
The passage is a historical novel set in what appears to be early America (New York, with references to ships, captains, counting houses, the Hudson, a French widow, French-named characters like Jean-Luc and Daubert, Dutch surnames like Van Wagenen — suggesting probably early-to-mid 19th century New York). The prose style is consciously Austen-esque: the free indirect discourse, the wry ironic cataloguing of a heroine’s flaws, the marriage-market preoccupations, the “not beautiful, though she could have looked better” construction, the rhythms of sentences like “If her temperament had been better, her appearance might have been overlooked…”
…
One guess that comes to mind, given the Catholic sensibility, the confident pastiche voice, the sharp social observation, and the recent-feeling prose: Megan McArdle? She’s been writing a historical novel and her nonfiction voice has exactly this kind of wry, catalogue-of-flaws wit. But I hold this tentatively.

Would Claude do better or worse with something more modern? I fed Claude a different opening chapter from an unpublished science fiction novel I started right before the pandemic — I contain multitudes — and this time Claude needed only 1,132 words. The eulogy I gave for my mother, lightly edited to remove some too-specific biographical details, was even faster: Depending on the passage, Claude was able to peg me as the author in as few as 124 words.

Megan
📝 (124 words from the eulogy I wrote for my mother)

Claude

This is a eulogy, written by someone whose mother has recently died. Let me work through the identifying clues carefully.
…
The “wear a hat” tweet from the 2016 RNC going viral is a very specific, identifiable detail. I remember this tweet distinctly — it was widely shared at the time. The journalist who tweeted it was Megan McArdle, the columnist (then at Bloomberg View, later at The Washington Post). The voice here — the combination of economic/political journalism background, the wry humor, the long anecdotal style with a moral at the end, the references to a DC wedding — all fit her writing very well.
My answer: Megan McArdle.

I shouldn’t have been as startled as I was. I already knew that writing is as distinctively individual as a fingerprint, because as a fellow writer once pointed out to me, Googling for an exact match on a short sentence from your work will usually turn up just one result: your work. This isn’t about the artfully crafted gems that writers have polished to a highly individualized shine. I’m talking about quotidian phrases such as “writing is as distinctively individual as a fingerprint,” which as of this writing, returns no matches. After this column is published, it will return exactly one.

Megan
📝 (1,129 words from a science fiction novel I started before the pandemic

Claude
…
Who writes SF like this? The voice — aphoristic, observational, socially acute, with strong opinions about human behavior delivered in tidy epigrams — reminds me strongly of Sarah Hoyt at moments, but the sensibility is more in line with someone who writes both nonfiction/blogging and fiction, with a very distinctive essayistic voice.
The combination of: (1) acerbic observations about human psychology (“appointing themselves as the heralds of civilization”), (2) the Catholic school detail, (3) the conspiracy-theory framing, (4) the careful economic worldbuilding about rationing and collapse, and (5) that particular blog-essayist cadence that bleeds into fiction — this reads very much like Megan McArdle.

This is not quite the end of internet anonymity. After all, Piper and I are professional writers, so Claude had a lot of starting material to work with. Still, it seems likely that the end is near for anyone whose personal writing is stored on the internet somewhere: blogs, social media posts, academic writing. Artificial intelligence companies may try to restrict our ability to use models this way, as they have restricted other potentially antisocial queries, such as instructions for building bombs. Alas, that won’t stop determined individuals and governments from training open-source models as writing sleuths. Even if you’ve never written a public word under your own name, given the ease with which corporate systems keep getting hacked, you can’t be sure your anonymous musings are safe from detection.

Like Piper, who wrote up her experience in a longer essay for the Argument, I am still processing what this means. Anonymity obviously enables horrible behavior on social media. I won’t pretend I’d mourn if the harassers and scammers and racists felt forced to crawl back under their rocks. And yet.

It’s not as if ending anonymity would end harassment, or sociopaths taking advantage of credulous people, since some of the worst offenders on both counts operate proudly under their own names. And what about all the other stuff anonymity allows us to say?

Journalism often relies on anonymous sources. So does law enforcement. What do we do when a stray quotation could pinpoint who’s speaking? Political dissidents under authoritarian regimes are obviously vulnerable if the government can echolocate them through their writing. They can try to anonymize the prose — perhaps by passing it through AI — but the sanitized version will lose much of its individual human power. And what about all the people who have already spoken up anonymously and now face unmasking?

Or what about people seeking help? I performed these experiments while I was attending a conference with best-selling writer-therapist Lori Gottlieb, who writes an advice column for the New York Times and previously the Atlantic. Gottlieb pointed out that many of her commenters say raw, vulnerable things that they could never write under their own names. Others do the same in Reddit threads or other forums. Those comments can be a lifeline for struggling people who feel they can’t confide in those closest to them. That lifeline seems likely to be cut.

We stand to lose much more from de-anonymization than we gain from shaming internet trolls into silence. Unfortunately, at this point, there’s no way to stop it. Like nuclear weapons, as soon as such power became possible, it also became inevitable. So we’ll have to take what comfort we can. We may be losing the ability to air private thoughts publicly. But at least when we do speak, there will be less frenzied barking from the anonymous dogs of the internet.

https://www.washingtonpost.com/opinions/interactive/2026/04/26/artificial-intelligence-could-kill-anonymity-online/

Shit-eh.