Open letters about AI development
- Source
- simonwillison.net
- Author
- Simon Willison
- Date

Context
The open letters collected by Simon Willison address different policy questions. Willison's August 2 overview brings together arguments about access to model weights, restrictions on model development and coordination over the speed of AI progress.
The Microsoft-led open-weights letter argues that downloadable models support competition, customer control and independent security work. Anthropic, in its response, explicitly rejects a blanket ban while advocating restrictions on advanced chips and industrial-scale , which uses one model's outputs to improve another.
The employee statement Pacing the Frontier instead asks for international tools to manage acceleration from automated AI research. Supporting wider model access and supporting coordination over future development are therefore separate positions. These letters express policy demands, rather than announcing enacted rules.
- The Microsoft-shepherded letter explicitly defends distillation — training one model on another model's outputs — as legitimate development rather than misappropriation, framing it as the same tradition of building on existing work that produced open source.
- Its safety argument inverts the usual one: closed models can be breached, misused, or fail in ways outsiders cannot detect, and concentrating capability in a few providers creates single points of failure and weakens competition.
- Anthropic's counter is narrower than a ban. Dario Amodei calls for cracking down on industrial-scale distillation operations while stating the company has never advocated banning models — the fight is over scale, not openness.
- The pacing letter asks the US government to back an international effort to develop technical and governance tools for deliberately slowing automated AI research. The urgency comes from AI already compounding AI work, like Anthropic writing 80% of its code with Claude Code.
- distillation — Training a small, cheap model to imitate a big one's outputs, keeping much of the capability at a fraction of the cost.
- open weights — A model whose trained parameters are published for anyone to download and run — unlike API-only models you can access but never possess.
“Relying solely on closed models is not inherently safe: they can be breached, misused, or fail in ways that outsiders cannot detect.”
“Distillation, or 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.”
“Anthropic has never advocated for a ban on open-weights models”
Dario Amodei
“We request that the U.S. government support an international effort to develop the technical and governance tools needed to deliberately pace the frontier of automated AI development.”
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