Sedevacantism

Sedevacantism, derived from the Latin sede vacante or "empty chair," is the subset of Radical Traditionalist Catholicism which holds that the popes since Pius XII are illegitimate, that is, they are antipopes. Sedevacantists not only reject the Second Vatican Council and its reforms of the Order of the Mass, but deny that the popes who promulgated and support them have any authority.

Some sedevacantists hold that Guiseppe Cardinal Siri was in fact elected pope during the 1958 conclave, based upon the ambiguous smoke that came from the chimney above the Sistine Chapel. However, according to the "Siri hypothesis," he was somehow prevented from actually taking the Chair of Peter, and replaced by Angelo Cardinal Roncalli, who took the name of John XXIII -- but could not have the papal charism of infallibility if there were in fact another man who held the positon.

However, few of them have a good answer for what would have happened to the true papacy upon Siri's death, since there was no sign of the sudden about-face John Paul II should have shown according to their theories of true Catholicism. Some claim that Siri in fact created an entire parallel heirarchy of secret priests, bishops, and cardinals, and his cardinals elected a new pope to replace "Gregory XVII" upon his death.

Sedevacantists who reject the Siri hypothesis generally cluster around the notion that a pope who willfully embraces heresy loses his claim on the Chair of Peter and thus loses the charism of infalibility as well. Some of them hold that there is no true pope, while others suggest that a pope who rejected Vatican II could once again enjoy the papal charism of infallibility and the true authority of the Chair of Peter.