I still do not understand how Fr. Calderon could acknowledge the doubts, yet conclude that since the NREC is "probably valid," therefore we can therefore go along with it, while the moralists teach us that with regard to sacramental validity, we must take a tutiorist position.

If someone could explain that seeming contradiction to me, it would be much appreciated.

Sean, the simple answer is that the SSPX priests were not taught the part bolded and underlined above. The SSPX seminaries must have provided a faulty education on that point.

As you say, it is demonstrably true that Catholic Moral Theology requires a Catholic to avoid any Sacrament that is not certainly valid (meaning by the standard of "moral certainty"). If there is any reasonable doubt about validity, even a shadow of doubt, if based on some kind of evidence or logic, then that Sacrament must be shunned (except possibly in a case of emergency).

The SSPX teaches the opposite: that one should only avoid a Sacrament only when one is certain that it is invalid. This is not Catholic teaching. The main problem now is the obstinacy of the SSPX priests in their error.

Hi Sean. I'm getting close to posting the full study of Fr Calderon in the English. It has been a painstaking translation and I am now into the footnotes (which are extensive). I want it to be perfect, not only linguistically but also theologically, so will have it endorsed by experts before posting.

Fr Calderon certainly doesn't say of the NREC that "we can therefore go along with it".

Note that the conclusion in the practical realm is twofold:

First, for those receiving the sacraments:
(i) Attending Mass (traditional rite) and receiving communion - permitted "occasionally". By "occasionally" I suspect he means 'for a sufficiently good reason', 'a proportional justification', rather than just 'now and then'.
(ii) Absolution - permitted in case of necessity.
"in all these activities our responsibility is not engaged concerning the priesthood exercised. And the remote risk that a communion or an absolution may be invalid is not so serious".

Second, for the authorities responsible for the exercise of the priesthood/episcopacy:
The positive and objective doubt make necessary the conditional reordination/reconsecration. Such doubt cannot be tolerated at the very root of the sacraments.

It is very clear what he considers the obligation of the SSPX authorities with regard to Bishop Huonder!

Here is his conclusion again, emphasis added:

Now, in a matter of the utmost importance for the life of the Church, such as the validity of the episcopate, it is necessary to have absolute certainty. Therefore, in order to be able to accept this rite with peace of conscience, it would be necessary to count not only on the judgement of theologians, but also on the infallible judgement of the Magisterium.

As for the practical attitude to be taken with regard to the new episcopal consecrations, the one that the Fraternity has maintained up to now seems to us to be justified:

1. The very probable validity of the rite seems to us to make it morally acceptable to occasionally attend Mass (traditional rite) celebrated by a priest or a bishop ordained or consecrated in the new rite, and even to receive communion therein; it seems to us acceptable, in case of necessity, to receive absolution from them; to treat them as priests and bishops and not as laymen in costume; it seems to us acceptable to allow them to celebrate in our own homes. For the shadows that hover over the validity of their priesthood are but shadows and in all these activities our responsibility is not engaged concerning the priesthood exercised. And the remote risk that a communion or an absolution may be invalid is not so serious.

2. But the positive and objective defects from which this rite suffers, which prevent us from being certain of its validity, it seems to us -until there is a Roman judgement, for which many things would have to change– justify and make necessary the conditional reordination of priests ordained by new bishops and, if necessary, the conditional reconsecration of these bishops. Such doubts cannot be tolerated at the very root of the sacraments (33).

Footnote 33 says "The moralists speak much about the necessity for certainty in the validity of the sacraments".