O'Malley and deterrence

I agree with Rob, of course, that the "step one" question about the death penalty -- i.e., is it a morally permissible punishment -- should not be answered in terms of its deterrence-related benefits.  And, while I do think that Gov. O'Malley's position and arguments have been (imperfectly) formed by Catholic teaching on the dignity of the human person, I agree with Rob that it would have been better had O'Malley made it more clear what "work" the deterrence-claims are doing in his argument.  He could have said, for instance, "Reasonable people can disagree about whether the death penalty, as a general matter, is consistent with our commitment to the dignity of the human person.  That said, even if the death penalty is sometimes justifiable, surely its costs -- financial and other costs -- and its lack of deterrence benefits -- weigh in favor of abolition."