Holden Karnofsky is one of the most influential people in the modern effective altruism movement and one of the most influential thinkers in the sphere of global AI safety discourse. As the co-founder of GiveWell and Open Philanthropy, he pioneered an entirely new style of doing massive amounts of principled giving, emphasizing significant research, unabashed openness and a search for the most effectual leverage possible. Throughout his now three-stage career encompassing hedge fund analyst, nonprofit innovation pioneer and now AI safety thinker, Karnofsky has increasingly defined his career with addressing the biggest issues of the age.
Karnofsky was born in 1980 or 1981 and grew up in the United States before obtaining an undergraduate degree in social studies from Harvard University in 2003. While at Harvard, he was involved in the Harvard Lampoon, a venerable humor publication that has introduced many talented Americans writers of comedy. Later, he took a job in the finance industry, at a hedge fund called Bridgewater Associates, located in Westport, Connecticut.
His work at Bridgewater was noticeable enough for a mention in the financial newspaper Barron’s, and it was at Bridgewater that he met his eventual research partner, Elie Hassenfeld. Serving at Bridgewater, Karnofsky and Hassenfeld decided to begin giving proactively. During this time in 2006, the couple created an informal charity club for their colleagues where they aggregated charitable gifts and elucidated which charities could best utilize the money. Though this exercise gave them clarity on how little most donors knew about their philanthropy.
Their analysis led them So that the world of funders needed an institution that functioned as an investment analyst does, evaluating nonprofits rigorously. In mid-2007, they decided to create such an institution using the Seed Round donation of their colleagues, creating a fund called the Clear Fund and quitting their jobs to work directly on a nonprofit, Give Well, whose goal is to identify the most rigorously justified charities and publish them all in a public fashion.
Give Well’s unique contribution was its radical transparency and rigorous standards. Instead of approving charities for their missions or even their overhead ratios, Give Well released the full details of how it was coming to its recommendationsan act of openness and accountability that was nothing short of revolutionary in philanthropy at the time. Over nearly a decade, Give Well garnered respect and influence, ultimately managing to funnel nearly a half a billion dollars per year into a small handful of charities tht had been evaluatedand approved under the organization’s standards, most of which work in the domains of global health and extreme hardship. Karnofsky had become a key figure in the emerging field of evidence-based philanthropy and effective altruism.
As GiveWell matured, Karnofsky’s own goals in the scope and scale of philanthropy expanded and it. In 2014 he co-founded the Open Philanthropy Project, an extension of Givewell Labsa joint project of GiveWell and Good Ventures, the philanthropic arm of Facebook co-founder Dustin Moskovitz, and his partner Cari Tuna. Open Philanthropy aimed at more highly-conjectural, longer-ti me giving opportunities for which GiveWell’s evidence-based model was not designed for; to host the lion’s share of Moskovitz’s multi-billion dollar philanthropic endowment in pursuit of causes with outsized, transformative potential.
Yamir occupied the role of CEO and later co-CEO of the organization, leading its giving programscovering global health science, pandemic readiness biosecurity land reform, farm welfare, and the existential risks of nextgeneration artificial intelligencewith distributions reaching hundreds of millions annually. By Yamir’s departure from direct management in 2023, Open Philanthropy had over 650 announced grants to over 370 recipientswith cumulative levels eventually exceeding four billion dollars, and transitioning to Yamir’s successor organization, Coefficient Giving. While at Open Philanthropy, Karnofskymoderated into one of the most popular current speakers within the effective altruism and AI safety communities.
His blog, Cold Takes, was a prominent outlet for his developing thoughts on some of humanity’s most critical longterm questions. His series, “The Most Important Century, ” advanced the case that the development of transformative artificial intelligence will probably make the present century one of the most singular eras in human history, with lasting impacts on the timeline of civilization. The series was carefully developed over many essays and proved highly influential within the EA movement, contributing to a significant centralization of the movement’s focus on AI risk as one of the most promising cause areas.
This was a natural evolution for him, and the deepening focus that would mark the next stage of his AI safety-related career. In 2024, he took up a Visiting Scholar position at the Carnegie Endowment for International Peace, developing research on international security risk from AI developments, including the principles behind voluntary safety commitmentsnamely, Responsible Scaling Policies. In January 2025, he joined Anthropic as a Member of Technical Staff, directly contributing to the design and implementation of the company’s Responsible Scaling Policy and its overall preparations for the imminent arrival of highly capable AI systems. Perhaps not surprisingly given the worlds we all move in, how Holden joins his professional and personal lives is a sign of their close proximity..
Married in August 2017 to Daniela Amodei, co-founder and president of Anthropic and sister of Anthropic CEO Dario Amodei, the couple have a son. [From 2017 to 2021, He sat on the board of directors of OpenAIwhich gave him long-term, early access to frontier AI technologies. He then married one of Anthropic’s cofounders and joined the organization itselfplacing him directly in the heart of one of the most important technological developments of the twenty-first century.
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