Authority to Change the Liturgy?

[UPDATE: See this post.]

As Catholics, we are bound to assent to the fact that the Popes have always had the authority to introduce certain changes into the discipline of the Church, including in her liturgies. This is taught authoritatively in several Magisterial sources. The Council of Trent teaches this; I believe Pope Pius VI teaches this in Auctorem Fidei; Pope Gregory XVI teaches this in Quo Graviora; the First Vatican Council proclaims infallibly the authority of the Pope even in disciplinary matters; Pope Pius XII teaches this in Mediator Dei; and Vatican II itself teaches this in Sacrosantum Concilium. And I am certain that there are many other sources which contain this teaching in them. 

That being said, never, to my knowledge, was it ever taught that the Pope had the authority to depart from or reject any of the immemorial traditions of the Church, even in liturgical matters. This is different than mere change; tradition, in fact, is entirely compatible with certain kinds of change. The traditional liturgy itself developed organically and gradually over a long period of time, yet always retaining the substance of its tradition, and growing more perfect as time went on. This development was always guided and approved, in one way or another, by the authority of the Church herself. But it was a development in which tradition was retained. Thus, history itself reveals to us that, until Pope Paul VI, never did the Popes assume the authority to abandon past immemorial traditions in the liturgy; nor was it ever taught or assumed that they had the authority to do so.

In the document Tuas Libenter, Pope Pius IX, following in the footsteps of St. Vincent Lerins, attributes a very great authority to the "common and constant consent of Catholics," by which the authority of tradition must be understood to be included; for tradition by nature involves the common and constant consent of Catholics. Pius IX says that the authority of such a common and constant theological opinion is very high, even if not high enough for the opposite error to be called strictly heretical. But he states emphatically that an error opposed to a theological opinion of such weight does indeed deserve some form of theological censure. It is clear then that tradition does not only apply to the doctrines of faith, but also to those matters which it is not strictly heretical to oppose.

Now, if we take one look at the "common and constant consent of Catholics" throughout the entire history of the Church, I am convinced that we will find no support for the opinion that the Pope could overthrow the received liturgy of the Church. On the contrary, we would find just the opposite opinion. Several theologians down through the centuries have stated explicitly that the Pope has no right to do so (some very authoritative have even said he would be a schismatic if he did so - a doubtful opinion in itself, but the principles are certain). But the general assumption has always been that the Pope could never bring about such a drastic change. If we follow the rule by which Pope Pius IX bound Catholics, I think that the opinion that the Pope could overthrow the received liturgy of the Church deserves some form of theological censure, because it is opposed to the common and constant theological opinion. 

There are instances, however, when the Popes would abolish traditions which had developed independently of the Church's own traditions, thereby leading to disorder and anarchy within the Church. Such was the case at the time of Pope Pius V's restoration of the Roman Missal. In Quo Primum, he explicitly and authoritatively abolishes certain liturgical customs, many of which had been long in use, but which had been formed not by an authentic development of the true ecclesiastical traditions, but by a kind of corruption of them. Therefore, Pope Pius V saw fit to forbid these traditions, and to restore the Roman Missal according to the authentic tradition of the Church, "to the original form and rite of the holy Fathers."

Thus, for the Catholic Church, tradition remained ever the norm and standard for liturgical development. The Popes never assumed the authority to reject the authentic tradition of the Church in such matters, even if they exercised the authority to introduce other changes which contributed to the gradual development of the liturgy. Tradition was always the norm.

And behold, there was the Second Vatican Council...

Pope Paul VI

The liturgical reform of Pope Paul VI seemed to change everything. Pope Paul himself admitted with the utmost clarity that the liturgical innovations which he introduced broke from the venerable tradition of the Church, which, he admits yet further, had previously been regarded as stable and untouchable. He thus admitted to having broken the pattern of his predecessors, to having departed from the ancient and immemorial tradition - not only the tradition of the liturgy, but also the tradition of Papal authority to change the liturgy. On what possible grounds can this be thought to be justifiable? There are none.