Venerable Pope Pius IX († 1878) recognized the danger that a future pope would be a heretic and teach contrary to the Catholic Faith, and he instructed, do not follow him.
If a future pope teaches anything contrary to the Catholic Faith, do not follow him." (Letter to Bishop Brizen)
And this is from the man whom under his pontificate, Papal infallibility was dogmatised
Just to clarify, Papal Infallibility does not mean the Pope is protected from erring whenever he is teaching on matters of faith and morals. That is a common misconception. What it does means is that a Pope is protected from error when he defines a doctrine of faith or morals to be held by the Universal Church. Those are the guidelines set down by Vatican I for the requirements for Papal Infallibility. The new Catechism uses the term "definitive act" to refer to the act of defining a dogma. Outside of the guidelines set down by Vatican I, a Pope can err. To say he can't is to assert what the Church does not teach.
Yes, but deposing a pope is entirely different from disagreeing with him. Deposing a Pope seems to completely undermine papal supremacy of jurisdiction...
Yes its impossible in the Catholicism. Yet the fact is explained by Pope Innocent III and St.Robert Bellarmine in that a pipe can be shown to be s formal heretic. A catholic ceases to be catholic once he entered
formal heresy and is thus a layman. Once shown to be a formal heretic he can be tried and judged
Pope Innocent III († 1216) stated that a pope can wither away into heresy and not believe the Faith.
"The pope should not flatter himself about his power, nor should he rashly glory in his honour and high estate, because the less he is judged by man, the more he is judged by God. Still the less can the Roman Pontiff glory, because he can be judged by men, or rather, can be shown to be already judged, if for example he should wither away into heresy, because "he who does not believe is already judged." (St. John 3:18) In such a case it should be said of him: 'If salt should lose its savour, it is good for nothing but to be cast out and trampled under foot by men. '" (Sermo 4)
The opinion of St. Bellarmine (which maintains that a heretical Pope automatically loses his office) does not preclude a judgment of guilt by the Church. It only maintains that the judgment does not cause the heretical Pope to lose his office, but rather confirms that he is guilty of heresy, and as such has lost his office
Deposing a pope also undermines infallibility in a secondary way. If a Pope makes an ex cathedra statement and someone disagrees with it they can argue that he should be deposed for heresy and the new dogma rejected. The idea of deposing a pope undermines the stability that the office supposedly provides.
Straw man. It would need to be the magesterium which shows the pope to be at least a material heretic as John XXII and if he refuses to accept correction he is thus a formal heretic, no more catholic an thus the person is being judged is not a Pope but a layman.
Secondly an Ex Cathedra Pronouncement cannot be heretical as the Holy Spirit guides the pope and protects him from teaching error when defining something to be held by all as a matter of faith.
Finally the Pope must deny a de fide doctrine for all this to happen.