So how do we square this tricky moral circle? Well, like most things it's pretty simple if you're prepared to adopt a radical and rational solution. Every nation on Earth should hand over the decision on capital punishment to a referendum of its electorate. There should be a free vote, on any and all aspects of the issue right down to the method used and whether the condemned gets a last meal
or not. But there's a small twist.
Supporters of the death penalty argue – either directly and openly or by unavoidable implication – that a few mistaken executions are a price worth paying, either for the deterrent effect or the principle of judicial vengeance. So the only reasonable thing to do is to make them face up to the reality of that situation, and to do that in the only meaningful way possible.
The names of everyone who votes "Yes" to retaining/restoring capital punishment must be recorded and entered into a lottery. On the first of every month, one name (or more, determined as a proportion of how many people that nation or state executes in a typical year) will be drawn at random and executed on the last day of that month by the nation/state's chosen method, with no exceptions or appeals.
After all, if you're willing to accept the state killing of innocents, you have to accept that one day it might be you (or your son or your daughter or father or mother or brother or sister) who is the innocent in question. Because everyone who's ever been wrongfully executed
was someone's son or someone's daughter, and why should you be magically exempt? If the random sacrifice of the innocent is a price worth paying to kill murderers, you must be prepared to pay it yourself.