It is not necessary to do both, of course. I fully agree with John Paul the Great, Benedict XVI, and others, that the death penalty is not a penalty that we ought to use. There is no doubt, however, that the Church does not deny the moral licitness of the penalty in principle. What John Paul the Great and Benedict XVI, among others, have denied, is the necessity of the use of the death penalty as a means for defending the common good. This is a prudential judgment, and the faithful are free, within certain very strict limitations, to think otherwise. And since it is permissible to think otherwise, it is, presumably, permissible to think the same thing but for different reasons, provided that those reasons are consistent with the Magisterium.
And therein lies the puzzle, or the worry, if you will. What if you think the same thing, but for different reasons that are not consistent with the Magisterium? Here's how Jamie concludes his essay:
Cardinal Ratzinger in 1996 described the Pope's teaching on the death penalty as a 'development of doctrine'. Part of this development, if Bottum is right, may be a subtle but definitive rejection of the 'argument from justice'.It is difficult to see how the "argument from justice", as Jamie puts it, can be "rejected" by the Magisterium since the argument from justice is, as a matter of fact, the only argument the Magisterium has ever used to defend the moral licitness of a particular form of punishment. To put it another way: the only possible justification for punishing a wrongdoer is that the wrongdoer deserves the punishment meted out to him. For example, if we were to apply the death penalty on the grounds that it deters crime (which it most certainly does do, regardless of what many studies appear to indicate, since it deters the person executed from committing any further crimes) then we would be acting prudentially, not morally, and our act would be done in the absence of any argument that the wrongdoer actually deserves to be executed rather than, say, locked up for life.
So while it is clearly the case that the Church's position with regard to the death penalty has, as a matter of fact, developed, it is quite impossible that the Church's teaching regarding any argument from justice is being changed in any way. To make that kind of an argument in support of John Paul's view would be to throw out any possible justification for punishment of any kind. And yet clearly we are required to punish, if only as a matter of fraternal correction.
Jamie's view is particularly puzzling since he bills himself as an "Augustinian"; but St. Augustine was a Platonist, and every Platonist knows that a wrongdoer needs his punishment as much as a sick person needs his medicine. To say that there can be any sense in which a punishment is not "deserved" as a matter of justice is quite out of step with any Augustinianism I am aware of. The question is not whether or not it is a matter of justice that the wrongdoer is to be punished; the question is rather what sort of punishment the wrongdoer deserves, just as the doctor's question is not whether or not to administer medicine to a sick person, but rather what sort of medicine is needed in this particular kind of case.
So the question at issue here should not be, what argument vindicates capital punishment, since we already know the answer to that question: the argument from justice (which ought not to be confused, as it appears to be in Jamie's post, with the notion of a lex talionis). The question ought rather to be, what manner of punishment is it, then, that the capital offender needs/deserves if we have decided that he does not necessarily need/deserve death?
It is tempting here to make a certain kind of mistake---the mistake of thinking that if death is not now necessary as a punishment, it never was. The Church clearly endorses the possibility, at least in principle, that death can be the punishment that is deserved, but of course the necessary and sufficient conditions for deserving death rather than some other punishment have never been codified or established de fide (we know only one of the necessary conditions: death may only be administered in order to protect the common good; but that is a hopelessly vague condition). So it is possible, at least, that death has never been deserved by any wrongdoer. But it is equally possible that some wrongdoers have, in fact, deserved death. And since John Paul's argument was grounded in an empirical matter, it is also at least possible that there are still some wrongdoers who deserve death, since it is possible that John Paul was mistaken in his prudential judgment about the present conditions for defending the common good (though, as I have said, I do not think that he was mistaken).
In reading Bottum's essay, it is tempting to find his argument congenial precisely because one finds his conclusion congenial. But that is a mistake that must be avoided, if we are to remain morally clear. If the conclusion is true, then there must be a sound argument for it; the task is not to rest content with whatever argument happens to stir our hearts, but to look for the argument that compels our assent.