I don't think I can agree with some of the statements of Fr. Gleize. His whole argument seems predicated on a very important premise, which he claims to be obvious: that there are contradictions in principle between past pronouncements and those of Vatican II. This, however, is what the whole debate is about. It is far from obvious, as there are very intelligent and knowledgeable people of good will on both sides of the debate.
With this premise in hand he goes on to show that applying a law of continuity to things definitely in contradiction is illogical. Given this premise, he is correct. But it remains to be seen if his premise is correct. He also presumes that Pope Benedict, Fr. Ocariz and others who argue that Vatican II's decrees can be understood in continuity with Tradition are doing so as if that premise were true--they are not. Their argument is that the principles are in continuity with Traditional principles--their argument is not that there is a contradiction and that we should pretend there is not. Fr. Gleize argues at length rightly against this latter argument, but that argument is not where the rub between the two parties is found in actuality.
Next, Fr. Gleize makes a distinction between the continuity of truth and the continuity of subject/Church. He argues that the Magisterium is only really the Magisterium when it maintains perfectly the constancy of truth, as opposed to the Magisterium’s authenticity being dependent on the unity and continuity of the subject/Church. If the SSPX position is the former then it actually sheds a lot of light on why their publications create dichotomies--as Fr. Gleize does in this very article--between "eternal Rome" and the Church of the city of Rome currently on earth, between the Magisterium of the past and the living Magisterium (ie the Magisterium exercised by those currently alive earth).
This is how Fr. Gleize can summarily dismiss the teaching of Vatican II as requiring no assent at all and of begging the question in claiming to require assent after finding what he sees to be four errors. Therefore, for him, those four errors he sees makes the Magisterium of Vatican II and recent Popes not the same one Magisterium that Our Lord has established from the Apostolic era to the end of time. On the other hand, the traditional principles allow for that one Magisterium to teach errors at times--the infallibility of the Magisterium has limits but the Magisterium itself is permanent and it is permanent in the offices traditionally associated with it. For example, Vatican I explained some of these limits and also taught the permanence of the Magisterium in certain offices (like the bishop of Rome).
Fr. Ocariz, on the other hand, applies the unity of subject in addition to the unity of truth. For him, the Pope and the entirety of bishops in Council teaching with him are exercising the one Magisterium of the Church that continues from the Apostles until the end of time and therefore deserve the assent Traditionally due to that same Magisterium. As opposed to the argument of Fr. Gleize, a teaching Pope and a teaching ecumenical Council always exercise the Magisterium at some level and therefore require the relevant level of assent. Those traditional levels of assent account for the potential of error in particular Magisterial pronouncements and tell us how to act when there is such an error. Fr. Ocariz’s argument, as I understand it, is we must give this traditional assent to Vatican II at the levels at which it teaches.
Because Fr. Gleize sees the Magisterium as being severed from the offices associated with it when any error is present, and given his other premise that there are actually contradictions that are obvious to all, he sees those who hold to the unity and continuity of the subject as necessarily making truth changeable and contingent on that subject. His conclusion is wrong because one or both of his premises are wrong.
This same mistake leads him to argue that it is wrong for the living Magisterium (as defined above) to claim for itself the right to interpret past Magisterial pronouncements. He argues that the Magisterium must also interpret. However, in doing so, he creates two different Magisteria--one now and one then--rather than seeing a unity in subject: the same Magisterium that exists in the past currently exists in the persons now alive holding the proper offices (or, more precisely, holding those offices at any point between 1962 and now). Those who are alive on earth currently exercising the Magisterium are the only ones who have the right and who are physically able to do the interpreting. This has always been the case. For example, some folks interpreted the Tome of St. Leo in contradiction with the anti-Nestorian decrees of the Council of Ephesus. The Council of Chalcedon, however, received the Tome of Leo as in continuity with what had previously been defined. The examples of this are too numerous to mention--practically every doctrinal controversy the Church has experienced has involved arguments over the meaning of various Magisterial pronouncements and it has been those alive exercising the Magisterium who have had to give the proper interpretation (the Jansenist controversy is a great example in more recent centuries). By creating two different Magisteria--one alive and without the ability to require assent and one “eternal” or of the past, we are left with the same problem as the Protestants. Sola Scriptura et Denzinger is not much better than Sola Scriptura.
Finally, Fr. Gleize makes a comment about the distinction between principles and concrete forms as being artificial when speaking of the social doctrine of the Church. However, the social doctrine of the Church is where these distinctions are most present. It is why Pius XI had to write Quadrigesimo Anno forty years after Rerum Novarum. It is why, concerning the changes in the social order in France, Leo XIII reminded some that, “In descending from the domain of abstractions to that of facts, we must beware of denying the principles just established: they remain fixed. However, becoming incarnated in facts, they are clothed with a contingent character, determined by the center in which their application is produced.” (Au Milieu des Sollicitudes 15).It is why temporal laws are conditioned on the needs of the common good and why they are mutable and changeable. Because Fr. Gleize says this distinction cannot be made and that he presumes everyone sees a contradiction in objective principles, he claims Pope Benedict’s attempt to make this distinction concerning Dignitatis Humanae cannot be made. It seems to that again one or both of his premises in this instance is mistaken.
To sum it up, because Fr. Gleize begins with two erroneous premises-- (1) that certain contradictions in principle are obvious and acknowledged (if even secretly) by all and (2) that the Magisterial authority is not permanent in the offices associated with it, but absolutely contingent on perfect constancy in all cases--his conclusions drawn logically from these premises miss the mark in my opinion.