Sign in Subscribe

AI / Anthropic / Claude / AI safety

A 'soul document' was found compressed in Claude Opus 4.5 model weights

Anthropic's staff philosopher confirms the discovery is based on a legitimate document used to train Claude's most recent model.

By Kiera Fields

Updated Dec 2, 2025 1:23 PM / Published Dec 2, 2025 11:55 AM 4 min read

A 'soul document' was found compressed in Claude Opus 4.5 model weights — Image credit: https://unsplash.com/@aoddeh

This content is for members only

Subscribe

Already have an account? Sign in

Add The Stack on Google

Kiera Fields

Kiera Fields is head of special projects at The Stack and was previously at Business Insider. She writes about leadership, tech and business, covering everything from earnings calls to C-suite interviews.