(Latin: in, not; fallere, to deceive) The preservation of the head of the Church of Christ from teaching error in matters of faith or morals. This preservation is due to the special assistance of the Holy Ghost, the Spirit of Truth, and is given in order that the faithful may be assured of the truth of their belief. In order to exercise this prerogative the pope must teach as doctor and pastor of all Christians in virtue of his supreme authority, not merely as a private theologian; he must teach a matter of faith or morals; he must define, with the manifest intention of obligating to consent; the definition must obligate the universal Church. The efficient cause of this infallibility is the Divine assistance. The object of papal infallibility is those truths contained explicitly or implicitly in the public deposit of Revelation, comprehended in Scripture and tradition. The ex cathedra definitions of the Roman pontiffs are irreformable of their very nature, independently of the antecedent, concomitant, or subsequent consent or concurrence of the Church, ie., the bishops and the faithful.