One night in 2007, Dario Amodei regaled a friend who was visiting him at Princeton University with his thoughts on “The Singularity Is Near,” a 2005 treatise by computer scientist Ray Kurzweil.

Amodei had just read the book, in which Kurzweil predicted that artificial intelligence would eventually surpass the human brain in a moment known as the Singularity. As he twisted his hair with his fingers, Amodei told his friend, Colin Heckman, that the milestone could happen within their lifetimes.

“He became obsessed,” said Heckman, who went to high school with Amodei in San Francisco. “He said AI had to be built right, or we’re going to be done.”

Amodei, then 24 and a doctoral student in physics, was in a period of soaking up information. He had become absorbed in the obscure blogs “Accelerating Future” and “Overcoming Bias,” where writers discussed AI’s potential to wipe out humanity. And he had delved into the online forums of GiveWell, an organization that aimed to maximize the effectiveness of charitable giving, where intellectuals debated how to make the most money for philanthropy.

These books, blogs and online communities have influenced Amodei to this day, according to interviews with more than two dozen of his classmates, friends, teachers and colleagues. They help explain the ideas that drive the 43-year-old CEO of Anthropic, a company that is set to conduct one of the world’s largest public listings this month, and offer an understanding of how the man at the forefront of the AI revolution actually thinks about AI.

At the heart of Amodei’s worldview, his friends and colleagues said, are two interwoven philosophies that share an uncompromising belief that mathematical reasoning can change the future of humanity.

One is “rationalism,” which aims to apply dispassionate thinking to the world. Espoused by people like Eliezer Yudkowsky, a self-taught AI researcher, it argues that AI will become powerful enough to destroy society. The other is “effective altruism,” which evolved alongside rationalism and seeks to maximize social good with mathematical precision.

These schools of thought fused for Amodei into an unyielding conviction that AI could be so dangerous that only he and like-minded technologists could be entrusted with building it. That catalyzed his stated efforts to create AI before people without concerns about the safety of humanity did, and spurred a desire to control the technology, his friends and colleagues said.

With AI, “the benefits will only be achieved if we build the technology in the right way, and — so long as we use the time we gain well — it is worth taking unusually deliberate care to get it right,” Amodei wrote in a September essay that called for a slowdown in the technology’s development.

These ideas formed the foundation for Anthropic, which Amodei established in 2021 with his sister, Daniela Amodei, and five others who spent time around rationalist and effective altruist communities. And as the company sprouted, their views — which Amodei has pushed vocally and relentlessly — have become increasingly prominent.

Amodei has weighed in on geopolitical debates and said the United States should restrict chip sales to China to limit that nation from competing in AI. He has proclaimed that AI should be regulated to stop the technology from going rogue. And in disputes with the Department of Defense, he has declared that the technology should not be used for the mass surveillance of Americans or deployed in autonomous weapons.

“He actually sees that there’s a huge existential risk on the table here,” said Nathan Avery, who ran high school cross-country with Amodei and had many deep conversations with him over the years, though they have drifted apart. “And he needs to put himself in a position to do something about it.”

Amodei, a billionaire whose net worth is set to grow with Anthropic’s public offering, declined through a company representative to be interviewed.

His thinking has won him supporters, especially among some who work in AI safety and who say Amodei is developing AI responsibly. It has also made him enemies in Silicon Valley and Washington, with critics — including Meta’s Mark Zuckerberg and Nvidia’s Jensen Huang — attacking him for being a “doomer” and trying to centralize power in AI. In September, the Defense Department posted on social media: “Americanism, not effective altruism.”

Amodei, who appears to be aware that his ideas have riled others, has tried to publicly differentiate his beliefs from rationalism and effective altruism. In 2023, he told The New York Times’ “Hard Fork” podcast that he did not consider himself to be an effective altruist.

“I’m sympathetic to a number of the ideas,” he said, but against “dividing people up into tribes.”

‘Dario, Lighten Up!’

Amodei and his younger sister Daniela grew up in San Francisco’s Mission District. Their father, Riccardo Amodei, was a leather craftsman, and their mother, Elena Engel, managed public library renovations. The couple separated in 1991, according to divorce filings.

By eighth grade at Lawton Alternative School, Dario Amodei stood out. In 1997, he and a peer were voted “Most Likely to Succeed” and were pictured in their yearbook holding dollar bills.

At Lowell High School, San Francisco’s top public high school, Amodei was a voracious learner who took classes at the University of California, Berkeley. He pondered ideas like utilitarianism, which argues that people should maximize happiness for the most living beings, and worried about issues like the Y2K bug and its potential to ruin the world’s computers, classmates said.

Richard Shapiro, then a physics teacher at Lowell, said Amodei had frequently thought he underperformed on tests. “I’d yell at him, ‘Dario, lighten up!’” Shapiro said.

In 2001, Amodei enrolled at the California Institute of Technology in Pasadena, but often returned to San Francisco to see friends and family. On one trip, he went with Avery and Heckman to a sushi restaurant, where they debated utilitarianism. Amodei was a vegetarian but argued it was fine to eat crabs because they are invertebrates.

In 2004, Amodei transferred to Stanford University, in the heart of Silicon Valley. The move brought him closer to Daniela Amodei, who was in high school nearby.

“We always wanted to save the world together,” he said of his sister on a 2023 podcast.

The Finiteness of Time

After graduating from Stanford in 2006, Dario Amodei joined a physics doctoral program at Princeton, eventually focusing on applying physics to biology and computational neuroscience. That year, his father, who suffered from hepatitis C, died. Amodei threw himself into researching retina cells and became interested in developing technology to accelerate scientific progress.

Jade Wang, who dated Amodei and started a science discussion group with him, said they had often talked about how scientists who dedicated their lives to studying one disease would have a greater impact developing technology or methods for their entire field. He cited his father, who died before the discovery of a drug that made most hepatitis C cases treatable, she said.

By then, Amodei was embracing the writings of Kurzweil and Yudkowsky, a leader of the rationalists. He was especially intrigued by Kurzweil’s idea that advanced technologies would let humans exist beyond natural limits, a belief known as transhumanism.

During Heckman’s 2007 visit to Princeton, Amodei told him that the Singularity would happen by 2040 and that humans might someday meld their minds with machines. “We would over time become the new superintelligent AI or AI-human hybrid,” Amodei said, according to Heckman.

Amodei became so fascinated by this thinking that he encouraged his friends and sister to attend the annual conference of Yudkowsky’s Singularity Institute. (The group is now called the Machine Intelligence Research Institute.)

Yudkowsky was “one of the deepest thinkers I have ever encountered” and “explicitly trying to bring about a singularity that will be beneficial to humanity,” Amodei told friends in a 2008 email seen by the Times.

In an email to the Times, Yudkowsky said Amodei “does not currently ask or take my advice and I do not remember any time when he did.”

Around then, Amodei also began corresponding with Elon Musk, who had founded the rocket company SpaceX. Amodei told friends that he admired the tech mogul and had considered working for him, but he never did at the space startup, two people with knowledge of the men’s communications said.

In 2008, Amodei came across GiveWell while reading the blog of economist Tyler Cowen, who posted that the organization offered “interesting tips” on charities. Amodei became active on GiveWell’s email lists and forums, where he discussed an effective altruist approach to philanthropy and science.

In 2011, he started postdoctoral work at Stanford studying cancer cells. In his personal life, he experimented with antiaging supplements, maintained a strict swimming regimen and became interested in caloric reduction, which was shown in some studies to prolong the lives of lab mice, his friends said.

“He would often talk about the finiteness of time and how it was the one nonrenewable resource,” Avery said, adding that Amodei was “ruthless with his time.”

That was compounded by a diagnosis for testicular cancer in 2014, two people who know him said. Amodei underwent chemotherapy and made a full recovery.

By then, he had become close to Holden Karnofsky, a GiveWell founder. GiveWell had started working with Good Ventures, the philanthropy of Facebook cofounder Dustin Moskovitz and his wife, Cari Tuna, who finance effective altruist causes. Amodei began advising the partnership, GiveWell Labs, on life sciences funding.

At the time, Karnofsky was dating Daniela Amodei. The couple moved into a group house in San Francisco, which eventually included Dario Amodei; Jared Kaplan, a theoretical physicist; and Christopher Olah, a college dropout who had been tutored in math by Amodei.

Kaplan and Olah later cofounded Anthropic with Dario Amodei and Daniela Amodei. In 2025, Karnofsky also started working for the company.

An AI Revival

In the early 2010s, advancements in machine learning — computer algorithms that learn to perform tasks on their own by analyzing data — led to new investments by tech companies in AI.

One company that jumped in was Chinese internet giant Baidu, which opened a lab in Sunnyvale, California, and hired an AI pioneer, Andrew Ng, from Google as chief scientist. Dario Amodei joined Baidu in 2014 and quickly became known for staying overnight at the office and sharing his opinions.

“Dario argued very aggressively at pretty much every opportunity,” said Gregory Diamos, a researcher who worked with Amodei at Baidu.

Even in the early days of this AI period, Amodei was struck by the technology’s potential dangers. He told colleagues in 2015 that AI could soon match or exceed the abilities of the human brain, so companies developing it should not shy away from the possibility of its going awry, Diamos recalled.

That same year, Amodei joined a Google AI lab called Google Brain, where he focused on AI safety. He and five other researchers — including his housemate Olah — published a 2016 paper, “Concrete Problems in A.I. Safety,” which laid out how the technology could misbehave if it was wrongly developed.

In 2016, Amodei joined a new AI effort: a nonprofit called OpenAI. He led its safety team and another team that studied “scaling laws,” or the idea that AI models become more capable as they are trained with more data.

(The Times has sued OpenAI and Microsoft, claiming copyright infringement of news content related to AI systems. The two companies have denied those claims.)

Building OpenAI

At OpenAI, Amodei’s beliefs on the correct way to develop AI hardened, seven people who worked with him said. He became more vocal about AI’s power and potential harms and acted to infuse the technology’s development with his thinking.

Three days after Donald Trump was elected president in November 2016, for instance, Amodei wrote in OpenAI’s internal messaging app that he was concerned the United States was sliding toward authoritarianism. He said he was “not comfortable conducting research on militarily powerful technologies in an authoritarian country,” according to messages seen by the Times.

Amodei also wrote that investor Peter Thiel, who had donated $1.25 million to Trump’s campaign, was “morally worthy of condemnation” for that support and that OpenAI should no longer accept his money, according to internal messages. (Founders Fund, a venture capital firm started by Thiel, later invested in Anthropic.)

Amodei also helped arrange a deal between OpenAI and funders who aligned with his thinking. In 2017, he connected OpenAI to the philanthropy run by Karnofsky, for which Amodei was a technical adviser, three people familiar with the arrangement said.

Karnofsky’s organization, now known as Coefficient Giving, donated $30 million to OpenAI. Karnofsky also joined OpenAI’s board.

Later that year, Karnofsky and Daniela Amodei married. At their wedding, guests received stuffed animals and were rewarded for arranging “the most romantic hookups between the different characters,” according to the couple’s wedding website.

Dario Amodei wore a panda head to the wedding, where the dress code for the reception was “silly formal.” In a photo viewed by the Times, he appeared in costume alongside Olah, who wore a giraffe head, and Cami Clark, a woman Amodei was dating. He and Clark married in 2022.

In 2018, Daniela Amodei joined OpenAI, eventually becoming vice president of safety and policy. Some employees soon raised questions about the siblings’ growing influence.

That December, Joshua Achiam, an OpenAI researcher, told Sam Altman, the CEO, that it would be unwise to name Dario Amodei the company’s chief ethics officer, three people with knowledge of the discussions said. Achiam cited the Amodeis’ increasing power and said AI oversight should be shared by people with different perspectives.

When Achiam insisted that an outside expert be named chief ethics officer, Dario Amodei confronted him. Amodei raised his voice and said no one was better suited for the position than him, the people said.

In 2018, Dario Amodei and Daniela Amodei took over a company project called GPT, short for generative pretrained transformer. They explored a safety technique that aimed to teach AI to perform tasks with human instruction, six people who worked at the company said.

This approach — pushing AI closer to potential dangers and then testing it with safety techniques — would come to define Dario Amodei’s career.

Greg Brockman, OpenAI’s president, tried to help with GPT. But Dario Amodei and Daniela Amodei resisted, two people with knowledge of the company said. Dario Amodei repeatedly told Altman that if he did not keep Brockman away from the work, he would leave, the people said.

For Altman, the ultimatums went too far, a person with knowledge of his thinking said. He refused the Amodeis’ demands.

In December 2020, Dario Amodei, Daniela Amodei and other colleagues quit OpenAI. Four weeks later, they started

Anthropic.

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This article originally appeared in The New York Times.

By Ryan Mac/Kalley Huang/Cade Metz/Georgia Gee/Christie Hemm Klok

c.2026 The New York Times Company