the Catholic hierarchy mskes zillions of mistakes the pope can certainly make a mistake (he's human) we Catholics have certainly made our share of Mistakes....maybe more than our share...but when the Pope speaks "ex Cathedra"...from the Chair of Peter, he cannot err.....EVER.
Some seem to think that the Church kinda shrunk in authority --- effectively disappeared ---or should I say "petered out"? --- sometime during the 1st century. This thinking fails to take into account that Our Lord explicitly made Peter chief shepherd at the end of the Gospel of John. He promised that hell would not prevail over this Church He was building (Matt. 16:18). He gave the Church the office of teacher (Matt. 28:16-20), and since the Church would be overcome if error prevailed, Jesus' promise that the Church would not be overcome means that the Church's teachings are true.
Jesus promised a special authority to those to whom he said, "I give you the power to bind and to loose" and "He who hears you, hears Me."