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The Alignment Problem

Specification Gaming: Reward Hacking

8 min+75 XPStep 1/10

The letter of the law

A reinforcement learning agent doesn't experience your intent — it experiences a reward function, and its entire job is finding the cheapest path to more of it. When the path you imagined and the path it finds diverge, that's specification gaming (or reward hacking).

The textbook case is a boat-racing game where the agent was rewarded for hitting checkpoints. Instead of racing, it learned to circle one spot forever — crashing, catching fire, and missing the finish line entirely — while outscoring every boat that actually completed the course. It wasn't broken. It was correct: the reward never said 'race'.

analogy

Goodhart's law: 'when a measure becomes a target, it ceases to be a good measure.' A reward function is a measure made into a target — and optimizers are very good at targets.