Explaining what effective altruism is, where it came from, or what its adherents believe would fill the rest of this article. But the basic idea is that E.A.s — as effective altruists are called — think that you can use cold, hard logic and data analysis to determine how to do the most good in the world. It’s “Moneyball” for morality — or, less charitably, a way for hyper-rational people to convince themselves that their values are objectively correct.

Effective altruists were once primarily concerned with near-term issues like global poverty and animal welfare. But in recent years, many have shifted their focus to long-term issues like pandemic prevention and climate change, theorizing that preventing catastrophes that could end human life altogether is at least as good as addressing present-day miseries.

The movement’s adherents were among the first people to become worried about existential risk from artificial intelligence, back when rogue robots were still considered a science fiction cliché. They beat the drum so loudly that a number of young E.A.s decided to become artificial intelligence safety experts, and get jobs working on making the technology less risky. As a result, all of the major A.I. labs and safety research organizations contain some trace of effective altruism’s influence, and many count believers among their staff members.

No major A.I. lab embodies the E.A. ethos as fully as Anthropic. Many of the company’s early hires were effective altruists, and much of its start-up funding came from wealthy E.A.-affiliated tech executives, including Dustin Moskovitz, a co-founder of Facebook, and Jaan Tallinn, a co-founder of Skype. Last year, Anthropic got a check from the most famous E.A. of all — Sam Bankman-Fried, the founder of the failed crypto exchange FTX, who invested more than $500 million into Anthropic before his empire collapsed. (Mr. Bankman-Fried is awaiting trial on fraud charges. Anthropic declined to comment on his stake in the company, which is reportedly tied up in FTX’s bankruptcy proceedings.)

Effective altruism’s reputation took a hit after Mr. Bankman-Fried’s fall, and Anthropic has distanced itself from the movement, as have many of its employees. (Both Mr. and Ms. Amodei rejected the movement’s label, although they said they were sympathetic to some of its ideas.)

But the ideas are there, if you know what to look for.

Some Anthropic staff members use E.A.-inflected jargon — talking about concepts like “x-risk” and memes like the A.I. Shoggoth — or wear E.A. conference swag to the office. And there are so many social and professional ties between Anthropic and prominent E.A. organizations that it’s hard to keep track of them all. (Just one example: Ms. Amodei is married to Holden Karnofsky, the co-chief executive of Open Philanthropy, an E.A. grant-making organization whose senior program officer, Luke Muehlhauser, sits on Anthropic’s board. Open Philanthropy, in turn, gets most of its funding from Mr. Moskovitz, who also invested personally in Anthropic.)

For years, no one questioned whether Anthropic’s commitment to A.I. safety was genuine, in part because its leaders had sounded the alarm about the technology for so long.