Agnosticism (A-gnosticism) means lack of knowledge or incertitude of truth. An agnostic is one who neither believes in God nor expressly denies the fact of His existence, but absurdly, claims to be in doubt over whether God exists (something He has revealed in creation itself with certitude) and thus lives like a practical atheist. Is this justifiable? By no means, St. Thomas says certitude belongs to the perfection of the intellect and God has revealed the truth we must know for our salvation and also by sending Christ His Son to found the Church has provided all the means we need to know the truth "with ease, with solid certitude and with no trace of error" (Vatican I, On Faith and Reason). And similarly sede-agnosticism or sede-doubtism professes to be uncertain or not know whether or not the See is occupied. Its most famous proponent on CI is Ladislaus.
But it's required that we believe in the legitimacy of a pope with the certainty of faith, since papal legitimacy is in the class of dogmatic fact ... I'm guessing that even Nishant would agree with me, right, Nishant?
1. The doctrine that Papal legitimacy (and a fortiori, the Ecuмenicity of a Council) is a dogmatic fact is not an argument in favor of doubt but rather against it. For, it is precisely that there be no doubt about a dogma defined by a particular Pontiff that the fact of his pontificate must itself be dogmatically certain. What is the use of the dogmatic fact if anyone can say, because he personally doubts the dogma of the Assumption, therefore he is justified in doubting the pontificate of Pope Pius XII, which some extreme sedevacantists in fact do? Like agnosticism in practice often reduces to sheer atheism, because it denies that man can attain to the knowledge of God with certainty (which is de fide, and easily provable by reason) so sede-agnosticism is simply an attempt to justify oneself remaining in doubt without resolving it by ignoring the means God has provided for us to be certain.
So what is sede-doubtism as defined by you, Ladislaus, is it a state of nescience, a professed uncertainty as to the fact of Papal succession looking for resolution either way? Is an agnostic historian who claims to be uncertain about the historical fact of Christ's Resurrection and the Church's divine origin justified in remaining in doubt? Why or why not? Neither are we justified in remaining in doubt about where Apostolic succession is continued, which the Fathers teach is a plain and evident fact by which all men in all ages can know the true Church with certainty.
2. We have to keep in mind the distinction between the epistemological and the ontological order, what is subjective and objective. Doubts do not exist in reality but only in the intellect, in the objective order, either the Pope is the Pope, or he isn't. If we lack certitude, then we should ask, like the agnostic historian should ask, what is the means that Almighty God, in His providence, has established for me to be certain? In the case of Christianity's divine origin, it is miracles and prophesies, as Vatican I says. In the case of identifying the true Church, it is the visible fact plainly evident to all of Apostolic and particularly Petrine succession. Once this Church has been identified by means of Apostolicity, we must ask who this Episcopal Body recognizes as Pope. The recognition of the other Successors of the Apostles is, in itself, a certain proof that a Successor of Peter exists.
So on what grounds do you affirm an individual layman, refusing the judgment of the entire episcopate who assures him day in and day out in the exercise of their ordinary teaching authority that we have a Pope, can still legitimately doubt whether a Successor of Peter has been elected. John of St. Thomas said it would be tantamount to heresy to deny the doctrine, even in principle, of universal acceptance providing infallible certitude of Papal legitimacy. Do you deny it even in principle, or do you only respectfully question its application to the post-Vatican II Popes, Ladislaus?
3. If the latter, can you please explain why you don't agree with this text, which Fr. Connell wrote in the AER in December 1965,
Question: What certainty have we that the reigning Pontiff is actually the primate of the universal Church – that is, that he became a member of the Church through valid baptism, and that he was validly elected Pope?
Answer: Of course, we have human moral certainty ... This type of certainty excludes every prudent fear of the opposite.
But in the case of the Pope we have a higher grade of certainty – a certainty that excludes not merely the prudent fear of the opposite, but even the possible fear of the opposite. In other words, we have infallible certainty ... The whole Church, teaching and believing, declares and believes this fact, and from this it follows that this fact is infallibly true. We accept it with ecclesiastical – not divine – faith, based on the authority of the infallible Church.