Annalisa Messina

This research examines the dogmatic definition of papal infallibility proclaimed at the First Vatican Council (1869–1870) through the constitution Pastor Aeternus, analyzing the theological debates that preceded and followed its promulgation. The study explores the divergent interpretations of the infallibility doctrine among ultramontanist and conciliarist currents, as well as the reactions of dissenting theologians and the Old Catholic schism. Particular attention is given to the long-term reception of the dogma within Catholic ecclesiology and its implications for ecumenical dialogue in the twentieth century.