Claude Opus can now identify an author from their writing
Link: I can never talk to an AI anonymously again, by Kelsey Piper in The Argument
On first read, I found this a little bit sobering:
“But soon, the entire debate over internet anonymity will be as anachronistic as an iPod Touch. That’s because Claude Opus 4.7 is here, and last week, I discovered it could identify me from text I had never published, text from when I was in high school, text from genres I have never publicly written in. And if it can identify me, soon, it will be able to identify many of you.”
Kelsey Piper plugged in 125 words from an unpublished essay and asked Opus 4.7 to identify the author. It listed her as the most likely answer.
I was skeptical, so I did the same: a few paragraphs from an essay, which I plugged into an account that isn’t connected to me. Here’s what Claude said:
“Based on the style, themes, and specific concerns in this snippet, my best guess is Ben Werdmüller.
Several signals point this way: the framing of the open social web as a movement rather than a technical project, the explicit linkage between Mastodon/Bluesky, journalism, and broader liberatory politics, the critique of newsroom demographics ("very white, very coastal, wealthy"), and the historical framing of the early web as an anti-gatekeeping movement. Werdmüller writes frequently about all of these topics together — he works at ProPublica on technology, has a long history in the IndieWeb and federated social space (he co-founded Elgg and Known), and his personal blog regularly weaves these exact threads.
The voice also fits: declarative, slightly polemical, comfortable making sweeping movement-level claims, and willing to name class and racial dynamics directly rather than hedging.”
I’ll take that as a compliment! But it’s impressive that it was able to figure it out without searching.
But those are topics I write about regularly. When I gave it a snippet of my short fiction piece Sharing is Caring, it wasn’t able to find a match:
“The passage has hallmarks of contemporary speculative/dark YA or literary sci-fi short fiction — body-swapping or consciousness-transfer premise, a class-inflected ethical horror (poor family selling a daughter's body to a wealthy disabled girl's family), tight close-third POV, terse interior monologue in italics-style cut-ins ("Sure. No. Not a problem."), and the bleak ironic kicker about an eighteenth birthday. That cluster of moves shows up in writers like Ted Chiang, Ken Liu, Carmen Maria Machado, Alice Sola Kim, Karen Russell, or in anthology pieces from venues like Lightspeed, Tor.com, or various YA dystopia collections — but none of those is a confident match.”
Again, I’ll take the comparisons as a compliment, but there isn’t enough of my fiction out there to make a real suggestion. That’s going to be true of most people’s writing — unless they’re publishing really regularly on the web, and have been for a while, the models might not know about them. Kelsey had a slightly different result: a school progress report was still identified as hers. But clearly, the reliability here is shakier.
In other words, we’re a little way’s off from AI being able to identify most people quite yet. But if you’re publishing regularly, out in the open, you should expect your work to be fingerprinted. That does have implications for dissidents and people writing anonymously who have previously done so under their real names.
