Murphy asks whether there is a non-Christian rationale for frowning on vengeance as a motivation for punishment. Why go through the intellectual hoops of finding a high-minded argument showing that a given punishment “fits” a given crime or of cooking up some far-flung utilitarian rationale for punishment. What we want is to get even. Why not fess up to it?
The objections to this proposal largely center around the untamed nature of feelings of vengeance: they can reflect social differences and not simply the nature of the crime, they can be extremely harsh, and they can attach to inappropriate objects.
Thus, white victims might be more offended by black criminals than by white ones. Taking their feelings into account would magnifying punishment along racial lines. The desire to “get even” frequently involves getting far more: think of collecting a pound of flesh for a debt. And we can want vengeance against people who have done nothing wrong. In some contexts, we have a name for it: road rage.
The case for vengeance depends on being able to discriminate between appropriate and irrational or inappropriate feelings. We do that with most emotions, so I don’t know that it’s impossible with vengeance. But perhaps it’s too difficult in this case.
In addition, it’s possible that we’ll want to override feelings of vengeance in pursuit of other social goals. In our society, the goal of combatting racial inequity has a strong case for taking precedence.