Since it is not papal infallibility the Vatican cannot, of course, by virtue of its own power make it infallible. But it seems rather that the Pope and the Bishops can have the role of confirming or verifying that something has indeed been taught infallibly by the ordinary magisterium. Confirming or verifying it-- making it manifest-- does lie within the Pope’s power, I would suppose, even if making it infallible by means of the ordinary magisterium is not. This distinction surely holds.
Verifying and confirming are two very different activities. Canon law 749 §3 states, “No doctrine is understood as defined infallibly unless this is manifestly evident”, not “… until it has been verified by the Pope.” So any papal role in verifying infallibility by the ordinary magisterium is a novel role that has developed since 1983, without an adequate explanation by the Vatican or the appropriate change to the canon law, the sudden development of which has thrown the Catholic theological community into a tizzy. Not to mention that you can’t “verify” something that isn’t true.
Confirming the brethren is what happened in Ordinatio Sacerdotalis, where the Pope took his place alongside his fellow bishops and acted as one of them. Lumen Gentium 25 gives the precise criteria for the ordinary magisterium:
Although the individual bishops do not enjoy the prerogative of infallibility, they nevertheless proclaim Christ’s doctrine infallibly whenever, even though dispersed through the world, but still maintaining the bond of communion among themselves and with the successor of Peter, and
authentically teaching matters of faith and morals, they are
in agreement on one position
as definitively to be held.
This lines up precisely with what John Paul taught in Ordinatio Sacerdotalis:
I declare that the Church has no authority whatsoever to confer priestly ordination on women and that this judgment is
to be definitively held by all the Church’s faithful.
The “in agreement” part of the Lumen Gentium condition has been interpreted by the magisterium (see
here) as follows:
The ordinary, universal Magisterium consists in the
unanimous proclamation of the Bishops in union with the Pope. It is expressed in the fact that
all the Bishops (including the Bishop of Rome, who is the Head of the College) give a common witness.
Thus, Ordinatio Sacerdotalis was just one bishop teaching precisely in the manner that
every bishop needs to be teaching, and that
every past bishop needed to have taught, in order to meet the conditions of infallibility by the ordinary magisterium. So how many similarly-worded statements are there available from other bishops, past and present, for verification?
I think you are right that it need be by divine law and not merely Church law, but you are wrong if you claim that it need be explicitly intended by each bishop. It could merely be implicitly intended, and this would be completely coherent with the development of doctrine.
The condition in Lumen Gentium refers to the “authentic teaching” of the bishops, not about what they merely implicitly believed. Binding magisterial teaching is just one example of a juridic act, the requirements of which are covered in canon laws 124-128 (see
here). It is hard to see how a bishop merely implicitly believing something can rise to level of a binding juridic act, much less the level (“to be definitively held”) required by Lumen Gentium.
As an off-topic example, John Paul clearly believed “implicitly” that the war against Iraq was morally unjustified. Because he chose to make his views know through the world media outlets instead by promulgating an official teaching, his views were (correctly) deemed as the “mere private opinion” of a Pope, not binding in the least on those who wanted to bomb Iraq back into the stone age. So if implicit teaching doesn’t bind at all, how can it bind infallibly?
Still working on responding to the rest…