I recently heard some lectures on religious liberty aimed at showing that there was no contradiction between the teaching of Dignitatis Humanae and earlier magisterial documents. They were learned and plausible. But they seemed to me to have a defect. They appeared to assume that it would be enough to demonstrate the absence of any such formal contradiction, in order to affirm that Dignitatis Humanae, taken to be declaring a right not previously taught by the Church, was a legitimate “development of doctrine”.

But such absence of contradiction is not enough. If I were to say, for example, that it is more virtuous to sit on the epistle side of church than on the gospel side, or more important for an island nation to have a good army than a good navy, then neither of these statements would contradict earlier magisterial teaching, as far as I know. Yet neither of them could therefore become objects of later magisterial teaching. Why not? Because they are not part of the revealed deposit that was complete with the death of the last apostle.

Since the revealed deposit cannot grow, development of doctrine can only mean expressing more clearly something which was found really, but less clearly, in the earlier tradition of the Church. One has to imagine someone at an earlier stage in the Church hearing the later formulation, for example St Ignatius of Antioch reading the Tome of Leo. If the earlier person would have said, “Yes, that’s just what I meant, only I never put it so well”, then we have a legitimate development. But if the earlier person would have said, “Well, I never heard anything like that before”, or “what on earth are you talking about?”, then it is no legitimate development, even if it is not in contradiction with what came before, and even if it is true.

Those who want to want to maintain that the earlier and later teachings on Church and State are both true and both authentic magisterial teachings, but that the later teaching is nevertheless importantly new, are faced with a problem. If it is new, how can it be the object of a magisterium whose sole duty is to expound the revealed deposit given once for all to the saints? They sometimes seek to resolve this problem by appealing to the notion of human dignity. The thought seems to be this. “Human dignity is part of the revealed deposit, and has always been upheld by the Church. In more recent times, the Church has become more conscious of the demands of human dignity. So at Vatican II she was able for the first time to teach the right to religious liberty. So the teaching is new, but we do not thereby fall into the error of continuing revelation, since the notion of human dignity, from which the teaching comes, was there from the beginning.”

There are two problems with this. First, there is the rule-of-thumb already mentioned. If the Fathers of the Church would have said “I never heard anything like that before”, then it is not a legitimate development. But if Vatican II was saying, as many people think, that pagans and heretics have a God-given right to be allowed to meet together for their worship and to be allowed to encourage others to join them, albeit a right that in some cases may be trumped by other rights, then I think the Fathers of the Church might well have said “where on earth do you get that idea from?” At least I know of nothing in them to think that they would have said, “yes, that’s just what I think, but I had never expressed it so clearly.”

Secondly, how, precisely, are we supposed to go from the notion of “human dignity” to the notion of religious liberty just outlined? Human beings have three modi sciendi, as far as I know: that is, three ways of going from less clear to more clear knowledge. These are traditionally called definition, division (e.g. triangles are isosceles, scalene or equilateral) and inference. Which one of these three is employed in going from “human dignity” to “right to religious liberty”? Is this right a part of the definition of human dignity? But people have had a concept of human dignity for centuries without grasping it by means of this right; and people today can still have the concept without accepting the right; so it does not look like part of the definition of an idea that was already generally accepted as belonging the revealed deposit. Again, “division” seems to have no place here. In what sense would one divide the notion of “human dignity” into “the right to religious liberty”, and what would the other members of the division be?

That leaves only the last modus sciendi, inference. Inference is either induction or deduction. But induction belongs to the world of experimental, empirical science, which is out of place here. So it must be deduction. But in that case, what are the two premises, certainly contained in the deposit of faith, from which the right to religious liberty is deduced?

It seems in reality as if the proponents of this kind of development of doctrine are imagining a kind of angelic intuition, whereby one would contemplate an essence (“human dignity”) and behold in it a property (“right to religious liberty”). But that is not given to mortals to do.