This from The Perils of Moral Outrage:
“Moral outrage is an emotion and a response tendency. The response tendency is to punish. In study after study, the most morally indignant subjects wanted to inflict the most pain on perceived violators of norms. A hundred lashes!
There can be a certain pleasure in moral outrage, especially if it is shared. Oh, those delicious fantasies of evil-doers getting their comeuppance: endless humiliation and pain. Just desserts for lacking sufficient compassion, for being selfish, for causing harm, and for not feeling bad enough about it.
Yet moral outrage is a response tendency that gets us into all sorts of trouble. Like love of sweets, it is a natural inclination that must be managed and restrained. For one thing, moral outrage makes us think in generalities, impairing our ability to think clearly about problems and issues. It reduces complexities to Us versus Them, Good versus Evil. The objects of moral outrage cease to be individuals and become examples, reduced to dehumanizing labels that place them beyond the reach of moral obligation: predators, parasites, malignant tumors.
To the morally outraged, justice is conceived as a righteous Reckoning, a collection of what is due. Punishment is a necessary payment to balance the books. But when is enough, enough? I don’t think moral outrage allows that calculation. When an individual is reduced to a dehumanized category, “enough” will never be reached. As long as the person has been essentialized as a predator, parasite or cancer, he will always have to pay.”
Ok, so moral outrage has its perils – but what about its weaker cousin, moral indignation? Sorry, no deal. With indignation there’s still the tendency to over-generalize and an urge to punish. These inclinations may have been useful over evolutionary time, when tolerance for transgressors could mean death to the group, but things are different now. The urge to punish as an end in itself – to make other people suffer to balance the books – is no longer necessary to keep transgressors in check.
Of course, some people need to be punished as a way to deter further bad behavior and protect the rest of us. We can still savor the satisfaction of someone getting their “just desserts” without elevating what is essentially a vindictive emotion to a moral principle.
Cass R. Sunstein & Daniel Kahneman. Indignation: Psychology, Politics, Law (John M. Olin Program in Law & Economics Working Paper No. 346, 2007).
David Moshman. "Us and Them: Identity and Genocide" (2007). Educational Psychology Papers and Publications. 87. http://digitalcommons.unl.edu/edpsychpapers/87