Reinforcement Learning Under Moral Uncertainty
This work addresses the challenge of creating morally-competent autonomous agents, which is crucial for safe deployment in domains like autonomous vehicles, though it is incremental as it builds on existing moral philosophy concepts.
The paper tackles the problem of training reinforcement learning agents to behave ethically under moral uncertainty, where multiple plausible ethical theories exist, by proposing two training methods and demonstrating in simple environments that such uncertainty can curb extreme behaviors from single-theory commitments.
An ambitious goal for machine learning is to create agents that behave ethically: The capacity to abide by human moral norms would greatly expand the context in which autonomous agents could be practically and safely deployed, e.g. fully autonomous vehicles will encounter charged moral decisions that complicate their deployment. While ethical agents could be trained by rewarding correct behavior under a specific moral theory (e.g. utilitarianism), there remains widespread disagreement about the nature of morality. Acknowledging such disagreement, recent work in moral philosophy proposes that ethical behavior requires acting under moral uncertainty, i.e. to take into account when acting that one's credence is split across several plausible ethical theories. This paper translates such insights to the field of reinforcement learning, proposes two training methods that realize different points among competing desiderata, and trains agents in simple environments to act under moral uncertainty. The results illustrate (1) how such uncertainty can help curb extreme behavior from commitment to single theories and (2) several technical complications arising from attempting to ground moral philosophy in RL (e.g. how can a principled trade-off between two competing but incomparable reward functions be reached). The aim is to catalyze progress towards morally-competent agents and highlight the potential of RL to contribute towards the computational grounding of moral philosophy.