Moral luck is the uncomfortable observation that our moral judgements of people are significantly influenced by factors beyond their control. The philosopher Thomas Nagel identified four types: resultant luck (what happens as a result of our actions), circumstantial luck (the situations we find ourselves in), constitutive luck (the kind of person we are), and causal luck (how we are determined by prior causes). Consider two drivers who both run red lights while drunk. One arrives home safely; the other hits and kills a pedestrian. Most legal systems — and most intuitions — judge them very differently, despite identical moral choices. Nagel argued that this reveals a deep incoherence in our practices of moral praise and blame. If we are partly products of circumstances, character, and chance that we did not choose, the concept of full desert becomes philosophically precarious.

💡 Did you know? Bernard Williams, who developed the concept of moral luck alongside Thomas Nagel in 1976, argued that the 'agent-regret' we feel when we harm someone accidentally — even with no fault — is itself evidence that our moral psychology does not fully separate outcomes from intentions.