The disposition of justice will lead the just person to resist unjust distibutions—and to resist them however they are motivated. This applies, very centrally, to himself. There are many enemies to fair conduct, both episodic and dispositional, and the person of just character is good at resisting them. This means that he will need, as Aristotle himself insists, other virtues as well: courage, for instance, and self-control. But the disposition of justice can itself provide a motive. The disposition to pursue justice and to resist injustice has its own special motivating thoughts. It is both necessary and sufficient to being a just person that one dispositionally promotes some courses as being just, and resists others as being unjust.
What then is the disposition of injustice? What is [it] to be a dispositionally unjust or unfair person? The answer surely can only be that it is to lack the disposition of justice—at the limit, not to be affected or moved by considerations of fairness to all. It involves a tendency to act from some motives on which the just person will not act, and indeed to have some motives which the just person will not have at all. Important among the motives to injustice (though they seem rarely to be mentioned) are such things as laziness or frivolity. Someone can make an unfair decision because it is too much trouble, or too boring, to think about what would be fair. Differently, he may find the outcome funny or diverting. At the end of that line is someone who finds the outcome amusing or otherwise attractive just because it is unfair.
(Bernard Williams, “Justice as a Virtue,” chap. 6 in Moral Luck: Philosophical Papers 1973-1980 [Cambridge: Cambridge University Press, 1981], 83-93, at 90-1 [italics in original])
Keith Burgess-Jackson, J.D., Ph.D. 