It is argued that the words in the post-Conciliar Form for consecrating Bishops, spiritus principalis, are insufficiently univocal (unambiguous) to denote the ordo episcopalis. I have pointed out that the same problem could be urged against the corresponding words which Pius XII declared to be the Form: ministerii tui summam (or its manuscript variant mysterii tui summam). But before 1947, the communis sententia among the approved manualists (this is summed up by Cardinal Gasparri, Secretary of State under Benedict XV and Pius XI) saw the Form for episcopal Consecration as being three quite different words, which had entered the Pontifical comparatively late: Accipe Spiritum Sanctum. Bishops, when consecrating a new bishop before 1947, intended to consecrate him when they opened their mouths and said these words, not when they uttered the words which Pius XII subsequently selected and declared to be the Form.
Are those three words sufficiently precise to indicate, univocally, the Episcopate? By your standards, O thou sedevacantist, surely not; they actually appeared also in the rite for ordaining a presbyter in the pre-Conciliar rites (they were said over me in 1968) and they could even without complete inappropriateness be linked to the Diaconate and to Confirmation. If (like popes, bishops and theologians for hundreds of years) you are happy with these vague words Accipe Spiritum Sanctum as the Form for episcopal consecration, why do you have a problem with the rather more explicit, distinctly less vague, words Spiritus principalis?
Cardinal Gasparri (this is a most interesting and telling point) also raised the hypothetical question of whether a consecrand would be validly consecrated if the whole of the ancient consecratory prayer were omitted and so all he had said over him were the three words Accipe Spiritum Sanctum. He concluded that this would be valid: "quia licet illa sola verba in se inspecta sint indeterminata, et non satis exprimant collationem ordinis episcopalis, tamen satis determinantur ... ipsamet caeremonia". Is your competence in these matters, O sedevacantist, really so much greater than that of the man who masterminded the production of the 1917 Code of Canon Law, Gasparri the Great?
The sedevacantist arguments urged against the validity of Consecrations performed with the post-Conciliar Pontifical do not hold a drop of water in them ... not a molecule. These arguments are shown to be baseless, not by deploying what some might dismiss as modernist, specious, flabby post-Conciliar arguments, but by understanding the standard texts and praxis of the pre-Conciliar Church.
I would have some sympathy with you, O sedevacantist, if all you desired to argue was that it was deplorable for the 1960s revisers, without any Conciliar mandate, to eliminate the ancient Roman Prayer for making a bishop (the theology of which can be traced back to the Letter to Corinth of Pope S Clement I in the 90s of the first Christian century) and to replace it by an Oriental prayer of unknown origin (but fashionable in the 1960s; the chairman of the coetus concerned with the Pontifical, Dom Botte, had himself produced an edition of it). A Catholic is not forbidden to entertain such a view. In fact, I hold it.
But that action, however deplorable, did not come within a million miles of rendering the Orders of the Catholic Church invalid.