Constitutional AI
Constitutional AI (CAI) is an alignment technique developed by Anthropic that trains AI systems to follow a set of principles (a "constitution") using AI-generated feedback rather than human feedback for each output.
Overview
Constitutional AI addresses scalability limitations of RLHF by using the AI itself to evaluate outputs against a set of written principles. This reduces the need for extensive human feedback while maintaining alignment with human values.
How It Works
The Constitution
A set of principles that define desired AI behavior. These might include rules about being helpful, harmless, and honest, as well as specific guidelines about refusing harmful requests.
Critique and Revision
The AI generates a response, then critiques its own response according to the constitutional principles, and revises it to better align with those principles.
Reinforcement Learning from AI Feedback (RLAIF)
A reward model is trained on the AI's own preference judgments (based on the constitution) rather than human preferences, then used for RL training.
Advantages
- Scalability: Reduces need for human feedback on every example
- Transparency: Principles are explicit and can be examined
- Consistency: AI feedback is more consistent than human feedback
- Harmful content handling: AI can evaluate harmful content without exposing humans to it
Limitations
- Principle specification: Difficult to write principles that cover all cases
- AI judgment errors: AI may misinterpret or misapply principles
- Bootstrapping problem: Relies on AI already having some alignment
Key Papers
- Bai et al. (2022) - "Constitutional AI: Harmlessness from AI Feedback"