Why did some bishops oppose defining papal infallibility at the First Vatican Council?

Some bishops opposed defining papal infallibility at the First Vatican Council for several reasons. A primary concern was that such a definition was inopportune, potentially widening the rift between the Catholic Church and modern society. Critics also argued that it presented a one-sided view of authority within the church, as bishops also possess powers of divine origin, not solely derived from the pope.1

Additionally, there were historical precedents that raised questions. Critics pointed to instances where popes were believed to have taught heretical doctrines, such as Pope Honorius I, who was posthumously condemned by the Third Council of Constantinople. Despite these objections, Pope Pius IX strongly advocated for the definition, and the Ultramontane party, who supported papal authority, ultimately succeeded in having the doctrine of papal infallibility formally defined in 1870.21345