Goodhart's Law in Reinforcement Learning
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Abstract (arXiv)
Implementing a reward function that perfectly captures a complex task in the real world is impractical. As a result, it is often appropriate to think of the reward function as a proxy for the true objective rather than as its definition. We study this phenomenon through the lens of Goodhart's law, which predicts that increasing optimisation of an imperfect proxy beyond some critical point decreases performance on the true objective. First, we propose a way to quantify the magnitude of this effect and show empirically that optimising an imperfect proxy reward often leads to the behaviour predicted by Goodhart's law for a wide range of environments and reward functions. We then provide a geometric explanation for why Goodhart's law occurs in Markov decision processes. We use these theoretical insights to propose an optimal early stopping method that provably avoids the aforementioned pitfall and derive theoretical regret bounds for this method. Moreover, we derive a training method that maximises worst-case reward, for the setting where there is uncertainty about the true reward function. Finally, we evaluate our early stopping method experimentally. Our results support a foundation for a theoretically-principled study of reinforcement learning under reward misspecification.
Key facts. Cited by 41 papers in the map (data through 14 Oct 2026). Builds on 17 of its 28 references that are in the map. First posted on arXiv 13 Oct 2023.
Builds on
17 of 28 references.
References · 17
- 2017Deep reinforcement learning from human preferencescited by 3,912
- 2022Scaling Laws for Reward Model Overoptimizationcited by 1,095
- 2017A Deep Reinforced Model for Abstractive Summarizationcited by 365
- 2022The Effects of Reward Misspecification: Mapping and Mitigating Misaligned Modelscited by 328
- 2018Reward learning from human preferences and demonstrations in Ataricited by 316
- 2018Categorizing Variants of Goodhart's Lawcited by 149
- 2021Reward (Mis)design for Autonomous Drivingcited by 104
- 2019Observational Overfitting in Reinforcement Learningcited by 91
- 2021Consequences of Misaligned AIcited by 80
- 2017Reinforcement Learning with a Corrupted Reward Channelcited by 70
- 2020Quantifying Differences in Reward Functionscited by 63
- 2022Invariance in Policy Optimisation and Partial Identifiability in Reward Learningcited by 46
5 more
- 2017Occam's razor is insufficient to infer the preferences of irrational agentscited by 45
- 2022Reward Gaming in Conditional Text Generationcited by 30
- 2022Misspecification in Inverse Reinforcement Learningcited by 27
- 2023STARC: A General Framework For Quantifying Differences Between Reward Functionscited by 15
- 2020Causal Campbell-Goodhart's law and Reinforcement Learningcited by 5
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Citing papers per year: 2024: 8; 2025: 6; 2026: 27.
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