I also believe the SSPX make propositions which have been condemned by Pius VI. Observe,
It is well known
traditional Catholic doctrine that ecclesiastical discipline can never be harmful or dangerous to the faithful, as was taught by Pius VI’s condemnation of the Jansenist proposition to the contrary [cf. Pope Pius VI, *Auctorem Fidei, 78 (1794).
See more here:
Are Ecclesiastical Disciplines Infallible?
According to Pope Gregory XVI,
Mirari Vos, 9 (1832):
“
the discipline sanctioned by the Church must never be rejected or branded as contrary to certain principles of the natural law. It must never be called crippled, or imperfect"
Pope Gregory XVI,
Quo Graviora, 4-5 (1833), admonishing those like the SSPX who "
state categorically that there are many things in the discipline of the Church … [which] are harmful for the growth and prosperity of the Catholic religion… these men were shamefully straying in their thoughts, they proposed to fall upon the errors condemned by the Church in proposition 78 of the constitution Auctorem fidei (published by Our predecessor, Pius VI on August 28, 1794)… do they not try to make the Church human by taking away from the infallible and divine authority, by which divine will it is governed? And does it not produce the same effect to think that the present discipline of the Church rests on failures, obscurities, and other inconveniences of this kind? And to feign that this discipline contains many things which are not useless but which are against the safety of the Catholic religion? Why is it that private individuals appropriate for themselves the right which is proper only for the pope?"
According to Pope Pius XII,
Mystici Corporis, 66 (1943):
“
Certainly the loving Mother is spotless in the Sacraments, by which she gives birth to and nourishes her children; in the faith which she has always preserved inviolate; in her sacred laws imposed on all; in the evangelical counsels which she recommends.”
I also refer you to the **1909 Catholic Encyclopedia, **written under the papacy of Pope St. Pius X, from an article entitled “
Ecclesiastical Discipline”, under the heading “
DISCIPLINARY INFALLIBILITY”.
newadvent.org/cathen/05030a.htm
Here’s an excerpt…
Disciplinary Infallibility] has, however, found a place in all recent treatises on the Church (De Ecclesiâ}. The authors of these treatises decide unanimously in favour of a negative and indirect rather than a positive and direct infallibility, inasmuch as in her general discipline, i. e. the common laws imposed on all the faithful, the Church can prescribe nothing that would be contrary to the natural or the Divine law, nor prohibit anything that the natural or the Divine law would exact. If well understood this thesis is undeniable; it amounts to saying that the Church does not and cannot impose practical directions contradictory of her own teaching.
From a
1908 source of Catholic doctrine, P. Hermann,
Institutiones Theologiae Dogmaticae (4th ed., Rome: Della Pace, 1908), vol. 1, p. 258:
“The Church is* infallible in her general discipline***. By the term general discipline is understood the laws and practices which belong to the external ordering of the whole Church. Such things would be those which concern either external worship, such as liturgy and rubrics, or the administration of the sacraments. . . .
“If she [the Church] were able to prescribe or command or tolerate in her discipline something against faith and morals, or something which tended to the detriment of the Church or to the harm of the faithful, she would turn away from her divine mission, which would be impossible.”
SSPX, railing agains this traditional Catholic doctrine, and contrary to Pius VI’s condemnation, reassert that present ecclesiastical discipline is harmful even in its approved form.
From the SSPX web page, citing Msgr Levebvre:
“The Novus Ordo Missae, even when said with piety and respect for the liturgical rules…bears within it a poison harmful to the faith” *(*Marcel Levebvre, An Open Letter to Confused Catholics, p. 29)
This proposition is the Jansenist claim all over again, which was already condemend by Pius VI. Traditionalist Catholics ought to know better.