[W]e can appeal to rights when moral matters have been settled. In other words, our appeals to rights may serve as shields, protecting our moral progress from the threats that remain. Likewise, there are times when it makes sense to use “rights” as weapons, as rhetorical tools for making moral progress when arguments have failed.

Joshua Greene, Moral Tribes: Emotion, Reason, and the Gap Between Us and Them, New York, 2013, p. 308