I oppose capital punishment on the grounds that the worst thing the state, with its monopoly on force, can possibly do is execute an innocent person. This, however, is the only argument against capital punishment with any merit. And of all the usual arguments, the worst is that to punish a murderer with death is “retributive” and “barbaric.”
Criminal justice does not operate on the “eye for an eye, tooth for a tooth” principle. It operates on the “two eyes for an eye, full set of bridgework for a tooth” principle. If I hold up a gas station for $200, the judge doesn’t order me to give the $200 back, apologize to the attendant for sticking a gun in his face, and leave it at that. He puts me away for a few years. Otherwise there would be little disincentive to hold up gas stations.
The punishment, as any parent could tell you, must exceed the crime. Not grossly exceed the crime, of course — one doesn’t execute jaywalkers even though this practice would doubtless eliminate jaywalking — but exceed it nonetheless. This does get dicey with particularly heinous, violent crimes like murder, maiming and rape. Still, one cannot accept the principle of punishment in excess of the crime, as most opponents of capital punishment do, and still grow weak in the knees over executing a murderer. It just isn’t logical.