PJ wrote, in response to a comment of mine to The Only Viable Threat:
I will take exception to your claiming deterrence of others as a legitimate purpose of punishment. It ought to be considered unethical to harm people for the purpose of teaching other people something. For example, if a judge determines that, based on the circumstances of the offense and a defendant’s background, he deserves 10 years imprisonment, but that if he is given a 25-year sentence it will deter a future crime, is it just for the judge to give him the 25 year sentence? Isn’t this only punishing the defendant for the future crime that somebody else would have committed? I actually think there are some serious due process issues implicated in that view.
I had taken for granted that general deterrence — like specific deterrence, incapacitation, and rehabilitation and unlike retribution — was a legitimate goal of punishment (just, I suppose, as most people take for granted that retribution is a legitimate goal of punishment).
Is it just? PJ’s question assumes that we can tell (“based on the circumstances of the offense and a defendant’s background”) what a defendant deserves. This is an assumption that I reject. Because we’re not omniscient, we can’t possibly know enough about a defendant’s background to know what he deserves. As Clarence Darrow said:
We have heard talk of justice. Is there anybody who knows what justice is? No one on earth can measure out justice. Can you look at any man and say what he deserves — whether he deserves hanging by the neck until dead or life in prison or thirty days in prison or a medal? The human mind is blind to all who seek to look in at it and to most of us that look out from it. Justice is something that man knows little about. He may know something about charity and understanding and mercy, and he should cling to those as far as he can.
This is why we’ve eliminated retribution as a goal of punishment — if we had the wisdom to know what each other deserved, retribution would be legitimizable.
I will consider this more carefully, but it seems to me that if we have eliminated retribution as a goal of punishment because we don’t really know what anyone deserves, then the question of punishment is a purely utilitarian one. We’re not giving people their deserts; we’re treating them in the way that we think will best balance the benefit to them with the benefit to society.