This is a column about AI. My fiancé works at Anthropic. See my full ethics disclosure here .

On Monday, after a weekend’s worth of concerned blog posts from OpenAI, I wrote about why we ought to take those warnings seriously. For a host of reasons, I wrote, AI companies make for flawed messengers on this subject: they can reasonably be accused of marketing, of blame-shifting, of regulatory capture, and more. And so I can understand why, despite a rising drumbeat of ominous talk over the past several years, the mainstream has largely written off existential risk as a fantasy.

Moments before I sent out that edition, though, a recently departed Anthropic researcher published an X post that brought the subject to the center of conversation. “I resigned from Anthropic today,” wrote a young researcher named Jacob Coxon, in a tweet that generated 159 million views. “I spent the last three years doing pretraining research at both OpenAI and Anthropic. Neither company is acting responsibly.…