Carney argues that the arbitrariness of the death penalty means that this punishment is not working to deter crime. Nor is it working as retribution. Neither of these moral purposes is fulfilled when executions are infrequent and random. Carney does not deny that the death penalty can be justified. Rather, he maintains that the current system does not live up to its own standards.

Carney’s argument raises the challenge of idealism and perfectionism in thinking about state-sponsored killing. He concludes that if the execution system does not live up to the ideal, we ought not employ it. One obvious response would be to fix the dysfunction in the system and make it less arbitrary. But until that is done, the judge ruled that executions are cruel, unusual and unconstitutional.

We usually don’t demand this sort of perfectionism. Schools, marriages and sports leagues rarely live up to our ideals. However, we don’t abolish them. Instead, we aim to reform them to bring them closer to the ideal.

Usually it is not wise to let the perfect become the enemy of the good. Perfectionism sets up a false dilemma: either perfection or abolition. The perfectionist false dilemma can lead us to jettison valuable but imperfect things. It can also cause us to give up the effort to reform and improve.

But state-sponsored killing seems to require a special and more perfect justification. If we are bothered by the arbitrary and capricious nature of the death penalty, then we should be even more worried about arbitrary and random killing in war. Consider the problem of collateral damage in war. Enemy soldiers are legitimate targets of justified warfare. But noncombatants — innocent civilians — are not supposed to be killed. Unfortunately, modern wars kill noncombatants in large numbers.

Defenders of the morality of war argue that civilian killing is permissible so long as armies do not deliberately target civilians. Critics of war reject this subtle moral point.

Critics argue that bad luck and accidental factors cannot justify the killing of the innocent. Following Carney’s reasoning about the death penalty, a critic might conclude that war ought to be abolished until we can ensure that wars are fought without creating collateral damage.

The analogy between war and the death penalty is not seamless. We presume, for example, that the convicted criminal is guilty of a crime and deserves to be punished, even though some death row inmates have in fact been exonerated. On the other hand, we presume that noncombatants are innocent and do not deserve the harm they suffer, even though the mothers and children of soldiers can work behind the lines to support the war effort.

A form of skeptical pacifism can result when we insist on perfectionism with regard to state-sponsored killing.

Until state-sponsored killing becomes less capricious and more deliberately targeted, the pacifist will say, states ought not kill.

Those not convinced by this argument will have to reconcile themselves to the apparent conflict between the arbitrary and random nature of state-sponsored killing and perfectionist idealism about justice.

A perfectly just system of state-sponsored killing would only kill those who deserve death and it would kill them in a fair and consistent way. A perfect system of state-sponsored killing would not bomb children or apply the death penalty in haphazard ways. It would give people what they deserve. And it would bring about good consequences. But of course, in a perfect world we would not need executioners or armies.

This line of thinking leaves us with a difficult decision. Should we demand perfection, or can we accept something less than perfection when it comes to war and the death penalty? This is a crucial and serious question for democratic citizens, since in a democracy state-sponsored killing is ultimately done in our names and on our behalf.