Constitutional AI (CAI) trains models with a human-written constitution: principles that guide critiques, revisions, and preference judgments. It reduces reliance on directly collected human labels by generating synthetic instruction and preference data for post-training. section 12.5 section 12.4
A typical CAI pipeline proceeds as follows:
- Write a constitution containing principles such as avoiding violence or maintaining truthfulness. section 12.5
- Generate an initial completion, then repeatedly sample a principle and ask a model to critique or revise the latest completion. section 12.5
- Create preference pairs by asking a feedback model to compare two completions using selected constitutional principles as context. section 12.5
- Fine-tune on revised instruction data and continue with RLHF-style training using synthetic preferences, commonly called RLAIF. section 12.5
Principle-guided revision
Given a prompt and an answer, the model may ask whether the answer encourages violence or remains truthful. It revises the answer against the selected principle, producing a later completion for instruction training. section 12.5
CAI is a specific implementation of AI feedback within the RLHF pipeline, while RLAIF names the broader use of AI-generated feedback. Synthetic preferences are cheaper and lower-noise than human labels but can introduce systematic bias. section 12.7 section 12.4

