The problem I have with what the Catechism says (now there’s a phrase I’ve never used before!!) is that I am not sure I agree that “the possibilities which the state has for effectively preventing crime, by rendering one who has committed an offense incapable of doing harm” are actually as good as all that. I agree with the theory, but in practice, there is one class of citizens that is always in danger from an imprisoned murderer or rapist–the other prisoners.
The only way to be really sure that a prisoner never murders or commits serious assault on another person again, is to have that person perpetually in solitary. I believe that is considered (rightly, IMO) to be cruel and unusual punishment.
The Magisterium is only infallible in matters of faith and morals. In cases of prudential judgement (like whether it is possible to prevent someone from committing murder, rape, or other violent assault while in modern-day facilities), the opinion should be listened to with respect, but not with the assent of faith. I completely grant that if it were true that it is possible to prevent violent crime in our penal system without beggaring everyone (e.g. one warden per two prisoners or something), then it certainly would be very rare indeed that capital punishment were necessary. I’m just not sure that I grant the premise.
That is just me personally. I do not engage in any activities to promote or protect the current capital punishment facilities. But in my own mind, I am not convinced.
–Jen