Christian Washburn has questioned my claim that the idea of a publicly heretical pope was formally excluded in Pastor Aeternus, by equating Bellarmine’s “fourth proposition” with the extreme Ultramontanist school of Albert Pighius. Washburn argues that Gasser had merely indicated that Bellarmine’s “fourth opinion” would be raised to dogmatic status, rather than the “fourth proposition.” I attempt to address this critique by demonstrating how Bellarmine’s own school of thought within the “fourth opinion” was markedly different from that of Pighius.

During the prelude to the First Vatican Council, the idea of a heretical pope was
used as the primary argument against the solemn definition of papal infallibility.
The medieval canonists and conciliarists had allowed for the notion of papal heresy
by making a strict distinction between the apostolic seat itself and the individual
occupants of the throne of Peter. However, when we examine the text of Pastor
Aeternus in light of the contents of the official Relatio, which was drawn up at the
council to explain the meaning of this document, we find that the above distinction
used by the conciliarists was formally proscribed with an anathema. This article will
argue that in doing so, the Council Fathers definitively excluded the possibility of a
heretical pope.