The liturgical reforms of the Second Vatican Council are “irreversible” and ensure that people rather than clerics are at the centre of Catholic worship, Pope Francis has said.

Delivering one of his most detailed reflections on the liturgy at the Vatican, the Pope invoked his “magisterial authority” to declare that changes to the Mass over the last 50 years – still hotly disputed by traditionalists – cannot be reversed.

The Pope’s address, given during Italy’s annual National Liturgical Week, pointed out that Pius X (1835-1914) and Pius XII (1876-1958) made their own liturgical reforms while the more dramatic shifts brought about by Vatican II did not “flourish suddenly” but developed over a long period of time.

Francis went on to describe the liturgy as “popular” rather than “clerical” stressing it is “an action for the people, but also of the people.” Quoting the Second Vatican Council’s document on the liturgy, the Pope said the faithful are not “strangers or silent spectators” during Mass but instead participate with “devotion and full collaboration.”

His remarks will be read as an attempt to draw a line under Catholicism’s liturgy wars which has seen traditionalists and progressives vigorously debate the changes to Catholic worship which took place in the years following Vatican II.

It was the council, which took place between 1962-65, which proposed that priests use vernacular languages instead of Latin, face the congregation and called for the people to actively participate in the Mass.

While there was a near unanimous consensus among bishops to reform the liturgy at the council, in the years afterwards a reaction against the changes developed calling for a “reform of the reform.” This group argue that the post-conciliar changes led to a dumbing down of the liturgy and a stripping away of its sacred elements.

Many critics are Catholics who remain attached to the pre-Vatican II version of the liturgy who were heartened when Benedict XVI loosened restrictions on celebrating the old rite a decade ago.

Under Francis, they have found a sympathetic ear from the Church’s top liturgy official Cardinal Robert Sarah, who has called for priests to face east while saying Mass and the incorporation of elements of the old rite into the ordinary form.

But the cardinal is at odds with the Pope who issued him with a rare public rebuke while overhauling the Guinean prelate’s department.

In recent months, however, Cardinal Sarah has struck a different tone calling for a “liturgical reconciliation” between old and new rites of the Mass while saying the phrase “reform of the reform” should not be used.

During his address the Pope said the liturgy is “life” and not an idea and transforms people’s way of thinking and behaving. This, Francis explains, is because, the Church is “truly living”, missionary and in its prayer life goes beyond just the Roman rite and includes the eastern Catholic ritual traditions.

“The liturgical renewal movement that preceded the Second Vatican Council (1962-1965) has been repeatedly and authoritatively recognized as a movement of the Holy Spirit in the Church.” What catches eye about Pope Francis’ recent remarks to an Italian liturgical conference is not, therefore, his strong endorsement of liturgical renewal, but rather some of the language he used to make that endorsement, language that one often associates with the exercise of the Church’s teaching office.

In phrases typically associated with formal, even infallible, teaching exercises, Francis purported to invoke his “magisterial authority” to “affirm with certainty” that the process of liturgical reform was “irreversible.” Such terminology coming from such a figure, predictably occasions questions about, among other things, whether such authority extends to declaring formally something (indeed, anything) about what is actually a process like “liturgical reform.” A blog post cannot, of course, do justice to all of the questions raised here, but it can perhaps contextualize some issues as a service for those interested in looking further into the matter.

Infallibility is a charism given to the Church by Christ which assures that some assertions, made by some persons, under some conditions, are asserted with the certainty of being without error and should therefore be accepted as certain (CCC 891-892). In itself, infallibility does not admit of degrees so a statement either satisfies all of the prerequisites for infallibility or it is not infallible (however likely or even true it might otherwise be). Infallible assertions, being certain in themselves, require Catholics either to believe the assertion (if it concerns faith) or to hold the assertion (if it concerns matters required to support the faith). See generally 1983 CIC 749-750. Finally, infallible assertions, although they might be clarified over time, are fundamentally irreversible, or irreformable, and so can never be cancelled or contradicted.

Now, setting aside some important points such as “subjects of infallibility” (briefly: the Pope alone per Canons 331 and 749 § 1; the college of bishops—which of course always includes the Pope—per Canons 336 and 749 § 2; and even the Church herself per, e.g.,CDF’s 1973 declaration Mysterium Ecclesiae, n. 2) and “modes of infallibility (chiefly: “solemn” or “extraordinary” in regard to papal and collegial teaching, and “ordinary” especially in regard to collegial teaching), it is in regard to the “objects of infallibility” that the Pope’s rhetoric about affirming with certainty and with magisterial authority that the liturgical reform process is irreversible strike as remarkable.