An act is wrong if no one could reasonably reject the rule behind it

T. M. Scanlon argued in 1998 that morality isn't about maximising happiness or following one master rule — it's about finding principles for acting that nobody, reasoning in good faith about everyone's interests, could reasonably reject. On this account, whether something is right or wrong tracks whether your justification for doing it could survive that kind of scrutiny from everyone it affects.

— T. M. Scanlon, What We Owe to Each Other — Harvard University Press, 1998