I have been rereading the 2003 article by the Byzantinist liturgical scholar and Jesuit, Fr Robert Taft, which deals with the 2001 Decision of three Roman dikasteries and of Pope John Paul II with regard to sacramental exchange between the Assyrian ("Nestorian") Church and the Churches in unity with Rome. You will remember that this Agreement adopted the principle that the Anaphora of Ss Addai and Mari, which lacks Words of Institution, was nevertheless sufficient for a valid Eucharist.
You get here a rather embarassing conflict between two different concepts of "Tradition". There can be a "narrower" view (in this case the instence in the Latin Churches that the Words are essential to Consecration*). "Traditionalists" can point to enactments of a more recent Magisterium which appear to offer strong support to the "narrower" view. On the other hand, it is possible to take a "broader" view (such as that adopted by the Vatican in 2001 and supported by Taft) which looks at undoubtedly "magisterial" facts such as the acceptance by the Roman Church for centuries of the sufficiency of Eucharistic Prayers which lack the Words. Each of these viewpoints can with considerable plausibility claim the support of both Tradition and Magisterium.
Advocates of the "narrower" view could attempt to trump the "broader" by pointing out
(1) that Tradition develops; so that what Pius VII said in 1822, being later than the praxis of the first millennium, is more "refined", ergo more "definitive"; and
(2) that the early centuries developed consensuses which it is not now open to us to unpick: such as the Canon of Scripture and the Threefold Ministry.
They could then plausibly argue that certain minimum ingredients, or structures, in a Eucharistic Prayer have that same degree of immutable canonicity. Taft, in my view, fails to acknowledge the strength of such arguments as these.
To these considerations I would add another: the Narrative of the Last Supper constitutes the only pericope in the entire Pauline Corpus giving a detailed account - words and actions - of an episode in the incarnate life of the Word. S Paul tells us that he had handed on to his Corinthian converts the Narrative which he had himself received. This is very far from proving that the Narrative was part of a 'Pauline' Eucharistic Prayer ... but ... it does make one wonder.
Nevertheless, I find it difficult to dispute the position adopted by the Magisterium in 2001 and vindicated in Taft's paper. An example of a 'magisterial' enactment which everybody for centuries has been anxious either to forget or to bury: the Decretum pro Armeniis of 1442 laid it down (among other things, such as the consecratory nature of the Words) that the Porrectio Instrumentorum is the Matter of the Sacrament of Order. But not only has this decree been treated as of no effect by both Leo XIII and Pius XII, it was not even viable in its own day - since the praxis of the See of Peter then, before then, and after then, was to accept that the Orders of all the Eastern Churches were valid despite their lack of this 'matter'. Taft deals with such impasses by elaborating what he calls principles of "ecumenical scholarship". Before we succumb to the temptation to See Red at this invocation of the divisive crunch word "ecumenical", I think we need to be fairly sure that we have a solution up our own sleeves which is better than his. I must confess that I do not.
Interestingly, in Taft's "Priciples of Ecumenical theology" there are some sections [my italics] which seem to me to relate not a little to the question of the Ordination of Women.
(1) The theological foundation for this method is our faith that the Holy Spirit is with God's Church, protecting the integrity of its witness, above all in the centuries of its undivided unity ...
(2) Secondly, the Catholic Church recognises the Eastern Churches to be the historic apostolic Christianity of the East, and Sister Churches of the Catholic Church. Consequently, no view of Christian tradition can be considered anything but partial that does not take full account of the age-old, traditional teaching of these Sister Churches. Any theology must be measured not only against the common tradition of the undivided Church, but also against the on-going witness of the Spirit-filled apostolic tradition of the East ...
(4) Those who have unilaterally modified a commonly accepted tradition of the undivided Church bear the principal responsibility for any divisions caused thereby ...
It is worthy of note that the innovations favoured by some Anglicans in the matter of women in sacerdotal ministry run directly contrary to an emerging ecumenical methodology the dynamic of which is to reconcile the Churches in full Communion with the Roman See of Peter with those ancient bodies which lack the fulness of that communion. The Anglican ecclesial community is thus navigating away, not just from the current magisterial locus of the Roman See, but from an ecumenical construct which, if anything, is even broader, and yet more ancient, and with greater testimonies from the Spirit-filled life all the Ancient Churches, than we ourselves have claimed.
The advocates of such innovations have long-since made up their minds upon the basis of considerations which lack any awareness of such points as I make above. The time for rational argument with them has long since passed ... even if, given the blind dogmatism of our opponents, it ever existed. But it is natural for Anglicans considering an Ordinariate solution to be quite clear about the imperatives which drive them; imperatives which are broader and more fundamental than even we ourselves claim.
* The Order of Communion of 1548 and the Prayer Book of 1662 reveal that the Church of England is doctrinally committed to the narrowest conceivable expression of this Western convention; Consecration is effected simply by reading the paragraph [Jesus Christus] pridie quam ... Corpus meum.