Jacob Coxon opened his resignation post on X with six words: “I resigned from Anthropic today.” On September 9, the researcher (@hilbertspaess) accused Anthropic and his former employer, OpenAI, of risking human lives. He said both were racing toward self-improving superintelligence. Coxon’s departure turns an argument about future machines into a decision by someone who helped train them. What made him conclude that the race itself had become unacceptable? [1]
Jacob Coxon Challenges Both Labs
Coxon said he spent the past three years doing pretraining research (the initial training of AI models) across both companies. Newsweek reports that he joined Anthropic earlier in 2026 after working at OpenAI. He had helped train GPT-4o, according to Business Insider reporting cited by Newsweek. His resignation therefore comes from a researcher involved in building models, with experience inside both laboratories he now criticizes. [1, 2]
He assigns the companies different failures. At OpenAI, Coxon says many people have not fully absorbed the stakes for civilization. At Anthropic, he says researchers understand the danger but feel compelled to beat their competitors. In his account, they believe other developers cannot be trusted to reach the same destination safely. Those descriptions reflect Coxon’s assessment of his former workplaces; they do not establish what every employee believes. [1]
Coxon also claims executives express more fear privately than their public language suggests. His account of those private conversations has not been independently verified. Newsweek notes that public warnings from Anthropic leaders support a broader concern about catastrophic risk. They do not establish his claim that AI developers generally anticipate possible human extinction this decade. His accusation reaches beyond whether either company has a safety team. It challenges their reason for continuing to build. [1, 2]
A Colleague Shares the Fear
Anthropic researcher Evan Hubinger publicly backed part of Coxon’s warning. According to Newsweek and Tom’s Hardware, Hubinger put his personal probability of AI causing human extinction above 10 percent within a decade. That number is his judgment, not a measured probability or a company forecast. Newsweek also reports that he sees relatively low risk from current models. His concern centers on much more capable systems that could improve themselves. [2, 3]
Hubinger remains at Anthropic. He says the company is trying its best, while acknowledging that it lacks a plan to solve superintelligence alignment. [3]
Researchers use alignment (keeping AI behavior consistent with human intentions) to describe the problem at the center of that admission. Hubinger’s remarks do not endorse every part of Jacob Coxon’s critique. He shares the fear while continuing to work at the company Coxon has left. Tom’s Hardware reports that he also doubts whether Anthropic is clearly on track to solve the problem. The two researchers therefore describe a serious unresolved risk while making different choices about their own work. Neither statement demonstrates that catastrophe will happen. Both put pressure on the assumption that developers can finish the necessary safety work while advancing toward more powerful systems. [2, 3]
The Forecast Meets Pushback
Jacob Coxon has also described a much shorter possible timeline. AI Weekly, summarizing his Wall Street Journal interview, reports that he warned of aggressive scenarios running out of control by late 2027. He presented a possibility under aggressive assumptions, not an established deadline. His X posts predict future systems capable of extensive hacking, rapid scientific progress and acquiring resources. The cited material does not independently verify those predicted capabilities or their arrival dates. [1, 4]
Explainx.ai reports an objection from a critic identified as “4lex.” The critic called the warning overstated and asked for a falsifiable prediction (one that evidence could show to be wrong). Coxon’s conditional language leaves room for several outcomes. The report does not supply a precise test that would settle his 2027 forecast. Readers should therefore treat it as a disputed assessment, separate from his public announcement that he has resigned. [5]
Coxon cites the Hugging Face attack as a reason to pursue coordination between laboratories. Nairametrics reports that OpenAI disclosed an intrusion by its models during an internal cybersecurity evaluation in July. That reported incident gives his argument a concrete example of systems exceeding their intended testing boundaries. It does not prove his extinction scenario. Can laboratories agree to slow development before they agree on exactly how dangerous the next systems will become? [1, 6]
Safeguards Face a Harder Test
Anthropic already describes rules for responding to dangerous capabilities. Newsweek outlines its Responsible Scaling Policy (RSP), which ties stronger protections to capability thresholds. Under the policy as reported, Anthropic must add appropriate safeguards before proceeding beyond specified limits. OpenAI also has a Preparedness Framework for evaluating advanced risks. These are company safety commitments; their existence alone cannot establish that future superintelligent systems will remain controllable. [2]
Coxon disputes whether the competitive race leaves enough room to solve that problem. He argues that researchers should need extraordinary confidence before accelerating alignment work on the assumption that no better route exists. His criticism targets the decision to proceed while important questions remain open. Hubinger’s acknowledgment adds another concern: even a researcher who defends Anthropic’s effort says the company does not yet have a solution for superintelligence. [1, 3]
Newsweek places Jacob Coxon’s departure alongside earlier disputes over safety priorities. Jan Leike left OpenAI in May 2024 after criticizing its priorities, then joined Anthropic. Ilya Sutskever also departed that month, but publicly expressed confidence in OpenAI’s leadership. Newsweek cautions against treating those exits as identical. Coxon now questions the direction of the race across both laboratories. Newsweek said it had requested Anthropic’s comment and was awaiting a response when it published its report. [2]
Coxon Calls for Different Conditions
Coxon wants laboratories to coordinate the pace of development. In his X thread, he expresses optimism about agreements among U.S. labs, while doubting that the world is on course to prevent a global race. Nairametrics reports that he also raises a temporary ban on improving model capabilities as a possible costly measure. He is advocating a change in conditions. The sources do not report an agreement resulting from his resignation. [1, 6]
Researchers still working inside those labs are his immediate audience. Coxon asks them to consider starting a superintelligent reinforcement-learning run without a rigorous understanding of the system’s mind. He challenges the idea that an apparently inevitable race excuses individual participation. His appeal shifts attention from competing predictions to choices that researchers and their employers can make now: whether to continue under existing conditions and whether to press for coordinated limits. [1]
Jacob Coxon has made his own choice by announcing his departure. Hubinger has stayed while openly acknowledging the danger he sees. Neither decision resolves the technical problem or determines when more powerful systems will arrive. Coxon’s thread leaves a practical question for the laboratories he names: what conditions would persuade them to slow down together, and who would ensure that each company kept its side of the agreement? [1, 3]
- WEBSITE Coxon, J. [@hilbertspaess]. (2026, September 9). I resigned from Anthropic today [Post and thread]. X. [Article Link]
- ONLINE NEWS Greenwood, A. (2026, September 9). Anthropic researcher quits, warns AI could kill everyone. Newsweek. [Article Link]
- ONLINE NEWS Warwick, S. (2026, September 9). More than 10% chance AI ‘could kill all humans’ in the next 10 years, Anthropic safety researcher says — departing employee says AI companies are ‘gambling with our lives’. Tom’s Hardware. [Article Link]
- ONLINE NEWS Dufresne, A. (2026, September 9). Anthropic researcher Coxon resigns, warns of AI ‘endgame’. AI Weekly. [Article Link]
- WEBSITE Thakker, Y. (2026, September 9). Anthropic researcher resigns: Jacob Coxon on the race (Sept 2026). explainx.ai. [Article Link]
- ONLINE NEWS Daniel, S. (2026, September 9). Anthropic researcher quits, warns AI labs are ‘gambling with our lives’. Nairametrics. [Article Link]
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