Yeah, like picking and choosing which doctrines in the Ordinary Magisterium to follow. Like you do.

A positive doubt about the validity of one's orders is not a doctrine. Therefore, avoiding those with doubtful orders is prudence, not generation of doctrine. Plus, it's one that would extend to the SSPX and Resistance as well, otherwise why would they conditionally ordain former NO "priests"?
Right, but Catholics are expected to identify other legitimate Catholics. And it is a doctrine that it is necessary that one is baptized and profess the true Faith in order to be a Catholic. Francis is certainly baptized, but he does not profess the true Faith.

Meg, you're presupposing that he is the Pope to begin with. You'd have a point if there were no doubts about that; but there are, which is why my position exists.

Catholic principles allow for it. See my previous post:

That being said, Catholics also do not have the right to pick and choose what doctrines of the Ordinary Magisterium to follow either.

Satis Cognitum #8
"It was consequently provided by God that the Magisterium instituted by Jesus Christ should not end with the life of the Apostles, but that it should be perpetuated. We see it in truth propagated, and, ‘as it were, delivered from hand to hand. For the Apostles consecrated bishops, and each one appointed those who were to succeed them immediately “in the ministry of the word.”

Nay more: they likewise required their successors to choose fitting men, to endow them with like authority, and to confide to them the office and mission of teaching."

This particular passage clearly shows that the Magisterium is most definitely a living, teaching episcopal body.  The authority to TEACH is perpetuated in the successors of the Apostles.  The deposit of faith is physically delivered, by the teaching authority of the Church, the Magisterium, by ordinary and extraordinary means, "from hand to hand."    

He continues:

Satis Cognitum #9
"The practice of the Church has always been the same, as is shown by the unanimous teaching of the Fathers, who were wont to hold as outside Catholic communion, and alien to the Church, whoever would recede in the least degree from any point of doctrine proposed by her authoritative Magisterium."

Proposed
verb
past tense: proposed; past participle: proposed
1. put forward (an idea or plan) for consideration or discussion by others.

A simple web definition shows that the Magisterium ACTS by PROPOSING doctrine.  

The Magisterium is literally the teaching authority commissioned by Christ Himself to go forth and teach all nations. 

Satis Cognitum #10
"But as this heavenly doctrine was never left to the arbitrary judgment of private individuals, but, in the beginning delivered by Jesus Christ, was afterwards committed by Him exclusively to the Magisterium already named, so the power of performing and administering the divine mysteries, together with the authority of ruling and governing, was not bestowed by God on all Christians indiscriminately, but on certain chosen persons.

For to the Apostles and their legitimate successors alone these words have reference: “Going into the whole world preach the Gospel.” “Baptizing them.” “Do this in commemoration of Me.” “Whose sins you shall forgive they are forgiven them.” And in like manner He ordered the Apostles only and those who should lawfully succeed them to feed – that is to govern with authority – alll Christian souls."

Again, given the context of the term Magisterium, used by Pope Leo XIII, I believe it clearly shows a physical office commissioned by Christ.  The Magisterium was established by Christ to guard and protect the whole of Catholic Doctrine - which is immune from all error. 

This post is not a 'pick on Meg' post but just a question, and is for anyone really as I used to be R'n'R -

Why are SSPXers attending illegal chapels founded by an Archbishop who is still officially excommunicated?  Have you determined through your own judgment that the popes have been teaching you error?  Or that an Ecuмenical Council has promulgated error?  Or do SSPXers just like the Gregorian Chant and the Latin Mass performed in illegal chapels?

Alas it looks like this thread has been degraded into yet another dose of sede vs R&R scurrility.

I agree the Magisterium is immune from all error, there is no doubt about that, since I've provided those quotes countless times. 

I can see where this thread is starting to veer off topic, so I won't say too much more on this.  However, I believe this confusion about the Magisterium stems from the larger problem of not recognizing the pope as our rule of faith.  Or at least failing to recognize the pope as our "proximate" rule of faith.