Gulielmus was the nephew of the famed Gulielmus Durantis senior, also known as the Speculator. He was born in Puimisson around 1266. While it seems likely that he studied law to some extent, there is no known record of his education. Gulielmus secured a number of benefices, including, by 1296, the archdeaconry of Mende, where his unlce was the bishop. That same year he became the bishop of Mende through papal reservation after the death of his uncle. As bishop of Mende, Guliemus also possessed secular jurisdiction in the region of of the Gevaudain. This was a source of contention with the French king, though Gulielmus and Philip II were able to come to an agreeable settlement. Gulielmus also continued to enjoy papal favor: in 1305–06, for example, he served as a papal legate in Northern Italy. He is more famous, however, for his support at the Council of Vienne (1311–12) for his support of the idea that the pope should not make general Christendom unless in consultation with a general council, which should be called every ten years. Gulielmus died in 1330 on his return voyage from Egypt, where he had been engaged in an embassy on behalf of the pope and the French king.

Gulielmus espoused his views on ecclesiology in the treatise known as the Tractatus de modo generalis concilii celebrandi, which he wrote on the occasion of the Council of Vienne. This particular title was likely the invention of a later printer at the time of the Council of Basel, when the treatise experienced a resurgence: manuscript evidence suggests that Gulielmus never named the treatise himself. Scholars had long pointed to contradictions within the work, but Fasoly shows that it can be divided into an earlier ‘Tractatus major’ and a later ‘Tractatus minor’, the latter of which seems to have been composed during the council itself in order to moderate the more radical calls for reform.

Entry by: KP rev BP 2015