Yes, a pope (or any Catholic) must be pertinacious in his heresy to be a formal heretic. If a Catholic forwards a material heresy without the pertinacity (the disordered act of the will) he is not a heretic in any sense.
Heresy, like any other mortal sin, must include the subjective elements of mortal sin (the proper “form”) which are “full advertence and perfect consent,” concurrent with the proper “matter” of mortal sin, which is “grave matter”, or else it is not “formal.” Thus, while heresy is indeed contrary to Divine law, it is contrary to Divine law whether material or formal, whether manifest or occult.
St. Pius X, in his defense against modernism states that he is “
leaving out of consideration the internal disposition of soul, of which God alone is the judge” (*Pascendi Dominici Gregis, *3). Consequently we ought not to concern ourselves with a matter of judgment that is the sole prerogative of God.
If the discussion is to be more than an academic one, then the process for determining whether one is a manifest heretic who is fully culpable of the penalty of excommunication, must be from
both the viewpoint of a moralist
and that of a canonist. One cannot simply choose one and omit the other. Where the moralist’s academic argument ends, the canonist’s practical argument must begin.
The problem with relying upon St. Robert’s
De Romano Pontifcae defense against Cardinal Cajetan’s contrary opinion is that it is an academic discussion
given the first premise does indeed exist, that the pope is a manifest heretic. However, in applying this argument pratically, we now have to ask how one can lawfully adjudicate a “doubt of fact” as to whether or not the pope is a “manifest” heretic.
There remains a practical canonical problem of defining what a “manifest heretic” is, and the practical canonical norms for judging the pope who, according to Catholic doctrine, nobody on earth has the authority to judge.
Furthermore, in applying the canonical norms to the particular case of a charge of heresy against the pope (who many, including the pope, do not agree is manifestly so), we are faced with a “doubt of fact” which must be resolved by lawful judicial means. Yet, with the particular case of applying the canonical norms to the pope, we inherently have a “doubt of law” which does not bind.
From a moralist point of view, we can never objectively know or judge the internal disposition of the pope’s soul. Consequently, the question whether the pope is a formal heretic by Divine Law alone is indeterminable because we only have recourse to the external evidence. From a canonist point of view, we lack canonical guidance in the particular case of adjudicating the “doubt of fact” as to whether “manifest heresy” of the pope exists or not. We are left with a doubt of fact coupled with a doubt of law until either pope himself or a successor pope resolves it.
