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Anthropic, notably absent from the open-weights letter's signatures, published its own response three days later in which CEO Dario Amodei warned of authoritarian governments building AI models more powerful than those of the US and of models being misused for cyberattacks or biological attacks, called for a crackdown on industrial-scale distillation operations, and stated that Anthropic has never advocated for a ban on open-weights models.

The author notes Anthropic declined to sign and instead published 'Our position on open-weights models,' in which Amodei warned about authoritarian regimes building more powerful AI and models being misused for cyber or biological attacks, called for a crackdown on industrial-scale distillation, and denied that Anthropic ever advocated a ban on open-weights models. ✦ AI generated

the author · Simon Willison's Weblog · 2026-08-02 · original ↗

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Notably absent from the signatures: Anthropic, who published their own response Our position on open-weights models three days later. CEO Dario Amodei doubled down on the risk of authoritarian governments building "AI models that are more powerful than those built by the US", and models being "misused to carry out cyberattacks or biological attacks", and called for "a crack down on industrial-scale distillation operations", while also stating that "Anthropic has never advocated for a ban on open-weights models".

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▦ Anthropic ✳ distillation ✳ open-weights models ◉ Dario Amodei

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Context · 1

Anthropic publicly claims it doesn't want to ban open weights, but its three positions — restricting chip sales to China, punishing distillation, and a government process to approve models — add up to a de facto ban and are a subtle form of regulatory capture; the letter's signers piled on mainly because everyone's business model improves if the two frontier labs can't extract ~$100B of revenue this year.Rory · 20VC · conf 80%

Counterpoint · 1

Policymakers should not conflate legitimate model-development techniques with misappropriation: distillation, the practice of using one model's outputs to help train or improve another, is a widely used technique for model improvement, evaluation, and validation that reflects a long tradition of learning from and building upon existing technologies.the Open Weights and American AI Leadership letter · Simon Willison's Weblog · conf 70%

This moment responds to

rebuts → Anthropic's three policy recommendations — restricting chip sales to China, punishing distillation, and requiring regulatory approval for models — would add up to de facto banning or slowing open-weight models, constituting regulatory capture.Rory · 20VC rebuts → Anthropic, as a private vendor, has every right to set and enforce its own terms of service with the Pentagon — including refusing certain uses — just as any vendor (like a lawn-care company) can decline a customer, since Claude is not a monopoly utility and competitors exist.Brad Carson · Machine Learning Street Talk