In 1948, Dom Gregory Dix wrote these words in a private (and unpublished) letter:
What are the minimum requirements for [Eucharistic] validity? I suppose: (1) a priest; (2) bread and wine; (3) the Words of Institution. (I personally would reduce this last to any plain indication that the rite now being performed with bread and wine by the priest is intended as a deliberate fulfilment of the command at the Last Supper, touto poieite eis ten anamnesin mou. A repetition of the Words of Institution is the most compendious and unambiguous and best authorised way of doing this.)
Dix was writing about the 1552 Communion Office, not Addai and Mari (the Assyrian Eucharistic Prayer which lacks an Institution Narrative). But I suspect he had AM in mind when adding his bracketed caveat. He more allusively suggests the same conclusion when discussing AM in Shape of the Liturgy. In effect, this is the very conclusion that Rome herself came to (see an earlier post) in its agreement with the Assyrian 'Church of the East', some sixty years after Dix wrote.
I suggest that this represents a theological method which is data-driven and has immense respect for Tradition - so that it finds it extremely repugnant to 'invalidate' a sacramental formulary which has de facto sanctified countless Christian lives for centuries. This method is in marked contrast to a theological method which works from theoretical first principles (to the time-conditioned subjectivity of which it is often blind) to a priori conclusions which may make a nonsense of historical fact. The most disastrous example of this latter method was Eugene IV's Decree for the Armenians. I think there is something rather Anglican Catholic about the data-driven approach; that it might even count as part of our Patrimony.
I suggest further that this cultural/methodological divergence is an example of what Manning had in mind when, writing to Talbot (a dodgy and theory-driven character if ever there was one) he so memorably criticised Blessed John Henry in the words "It is the old Anglican, patristic, literary, Oxford tone transplanted into the Church". I would add to Manning's adjectives another: "historical".
It is Newman, not Manning, who has been beatified; Newman, not Manning, who is Benedict XVI's bed-time reading. Four cheers for the Old Anglican Patristic Literary Historical Oxford Method! I wonder if our Holy Father has copies of Dix?*
*I am certainly not suggesting that all RC theologians are theory-driven and all Anglican Catholics data-driven (or even that the two methods are exclusive, or that they inevitably reach conflicting conclusions); life certainly isn't as clear-cut as that. As an example of a very data-driven Roman theologian I would offer Benedict XIV (the last Pontiff before Benedict XVI to achieve enormous distinction from his writings as a private theologian); my own excursions into this massively and historically erudite pontiff suggest to me that he also was rather an Oxford-Newman-Dix sort of chap at heart ... the sort of bloke you could easily run into lurking behind a pile of folios in Duke Humphrey ... and that he could do with some resurrecting!