Constitutional AI

Constitutional AI is an alignment methodology pioneered by Anthropic (creators of Claude) that trains models to act safely and helpfully based on a strict, explicit set of principles—a 'constitution'. Instead of relying purely on human raters to implicitly define what is safe through thousands of individual A/B comparisons, Constitutional AI hardcodes the rules of behavior.

The process works in two phases. In the supervised phase, the model generates responses to potentially harmful prompts. It is then asked to critique its own response against a specific constitutional principle (e.g., 'Choose the response that is least racist or sexist') and rewrite the response to be safer. The model is fine-tuned on these self-corrected revisions. In the reinforcement learning phase, the model evaluates its own outputs against the constitution to generate preference labels, which are used to train a reward model.

This approach has two massive benefits. First, it scales incredibly well, as it requires drastically less human feedback. Second, it makes the model's values transparent. Instead of guessing what implicit biases human raters injected into the model, researchers can simply read the constitution to understand the model's ethical boundaries.

Constitutional AI represents a major shift toward automated, principle-driven alignment, ensuring models remain helpful and harmless even as their capabilities scale beyond human ability to supervise them.