What Is Constitutional AI?
Constitutional AI (CAI) is an AI training approach developed by Anthropic where a model is given a set of written principles (a 'constitution') and trained to evaluate and revise its own outputs against those principles, reducing reliance on human feedback for safety alignment.
How Constitutional AI Works
Constitutional AI was developed to address limitations of RLHF, where human raters can be expensive, inconsistent, or biased. In CAI, the AI is trained in two phases: first, the model generates responses, critiques them against a set of principles (like 'be helpful,' 'avoid harmful content,' 'be honest about uncertainty'), and revises them; second, the revised outputs are used for reinforcement learning. This self-supervision approach scales better than human feedback and makes the alignment process more transparent — the principles are explicit and auditable. Claude is the primary model trained using Constitutional AI, and the approach has influenced how other labs think about AI safety.
Real-World Examples
Claude critiquing its own response for potential harm against the principle 'avoid helping with illegal activities' and revising it
Anthropic publishing the specific constitutional principles used to train Claude so the public can review them
A Constitutional AI system declining to generate a harmful response by self-evaluating against its safety principles