Opinion: How Artificial Intelligence Threatens Online Anonymity
By Megan McArdle | The Washington Post | April 26, 2026
The Internet is a place for free action. It grows with anonymity. A famous New Yorker cartoon shows that, saying, “On the Internet, nobody knows you’re a dog.” Now, artificial intelligence works in a new way. AI can match a writer’s unique style. It finds clues in every word. It works even for texts that are not public.
Testing AI’s “Echolocating” Powers
Last week, Kelsey Piper shared an experiment on Twitter. She gave an unpublished 1,000-word scene to the AI Claude Opus 4.7. The AI named her as the writer without delay. I felt drawn to try my own test. I used text from a romance novel that I began twenty years ago. With 1,441 words, Claude picked me as the author. I cut the text further. I wanted to see how few words the AI needed. The results came out clear. Longer texts made the AI almost certain of my identity.
I then tried a science fiction draft. With 1,132 words, the AI labeled me correctly. More surprising, a 124-word eulogy I wrote for my late mother was enough. Even a short, intimate text shows a clear digital fingerprint.
Why Writing Is Like a Fingerprint
Every writer has a unique voice. Each sentence connects closely with its nearby words. When you search a sentence online, you rarely find an exact copy. That sentence belongs only to you. AI goes further by scanning word choices, rhythms, and structures. It uses each link between words to find who wrote the text. This process works like a natural sonar.
Implications for Privacy and Society
Does this end online anonymity? Not yet. But the effect is deep. Professional writers, with many published and private texts online, are easy to identify. Then consider millions who post blogs, tweets, academic articles, or forum comments. AI can match their styles too. Governments, both elected and authoritarian, along with private individuals, may expose anonymous writers.
Some companies may try to limit these AI skills. They can block harmful queries, for instance. Yet open-source models remain free and changeable. This freedom makes it hard to stop those who want to use writing patterns to reveal authors.
The Erosion of Anonymity’s Value
Anonymity online shelters many types of people. It can hide trolls and scammers, but it also protects whistleblowers and political dissidents. Journalists depend on anonymous sources for safety. Law enforcement values confidential informants. If AI can unmask the writer by matching style, the results could be grim.
Authors might try to disguise their writing. They could run text through AI or other tools to scrub their voice. But this can weaken a text’s authenticity and feeling. Losing anonymity may stop honest voices. It might silence minority groups and hurt free debate.
A Future Without Anonymity?
AI’s power to find a writer is as inevitable as nuclear technology once was. We cannot fully stop this trend. Yet society must decide what it will lose. The freedom to share private thoughts, to speak in confidence, and to avoid retaliation is at stake.
Perhaps the anger of online abuse will lessen. Still, we need to ask if losing our private space is a price we can bear.
Megan McArdle is a columnist for The Washington Post and author of "The Up Side of Down: Why Failing Well Is the Key to Success."
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