That, I think, is part of the nature of beliefs about justice—they are absolute, bright edged, in a way in which preferences are not. The point is summed up in the Latin phrase Fiat justicia, ruat coelum—let justice be done though the sky falls. Those whose bumper stickers read "If you want peace, work for justice" simply take it for granted that there is no question what is just; if you want to find out, just ask them. The problem with the world as they see it is merely that other people are insufficiently virtuous to act accordingly.

-- David D. Friedman, If you want war, work for justice