What is
Ex Cathedra?
What is
Infallibility?
The teaching of the Vatican Council is to be found in Session III, cap. 4, where it is declared that “the doctrine of faith, which God has revealed, has not been proposed as a philosophical discovery to be improved upon by human talent, but has been committed as a Divine deposit to the spouse of Christ, to be faithfully guarded and infallibly interpreted by her”; and in Session IV, cap. 4, where it is defined that the Roman pontiff when he teaches ex cathedra “enjoys, by reason of the Divine assistance promised to him in blessed Peter, that infallibility with which the Divine Redeemer wished His Church to be endowed in defining doctrine regarding faith and morals”.
Is in short the pope is ONLY infallibile when teaching ex cathedra