[gbcdoj]

any more than Pope St. Pius V had the authority to bind his successors on prudential matters such as banning any changes of liturgy as he purported to do in Quo Primum.

Just a note - the language in "Quo Primum" was usual for pontifical documents of that time. It was never meant to impose an obligation on Pius' successors - he knew very well that he could do no such thing.

[BlackElk]

That's a relief but try to convince the usual gang of suspects! Now, there's the challenge! Is there a definition of "invincible ignorance?"

[CatherineSiena]

Just a note - the language in "Quo Primum" was usual for pontifical documents of that time. It was never meant to impose an obligation on Pius' successors - he knew very well that he could do no such thing.

Can you site another pontifical document with similar language over a disciplinary matter? (this is a curiosity question, not a challenge)

I've always thought that Pius V did intend exactly what his words said he did, but since he has no power to bind his successors, it didn't matter.