Writing style as your digital fingerprint

Apparently, the words we use and how we structure our sentences in writing is nearly as unique as our fingerprints. Kelsey Piper has been using this to benchmark new LLMs by entering text and asking who wrote it. Anthropic’s Opus 4.7 model was the first to return all the correct answers.

For WaPo opinion, Megan McArdle tested the search with her own unpublished text.

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 I fed Claude a different opening chapter from an unpublished science fiction novel I started right before the pandemic — I contain multitudes — and this time Claude needed only 1,132 words.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.

I’m too scared to try this on myself, but I’ll assume it works. Lucky for me, I’ve always written and made things with the assumption that my mother would see it.

However, if you publish words or share thoughts on social media, I hope you don’t value online anonymity too much.