Papal primacy, also known as the primacy of the bishop of Rome, is an ecclesiological doctrine in the Catholic Church concerning the respect and authority that is due to the pope from other bishops and their episcopal sees. While the doctrine is accepted at a fundamental level by both the Catholic Church (Eastern and Western) and the Eastern Orthodox Church, the two disagree on the nature of primacy.
English academic and Catholic priest Aidan Nichols wrote that "at root, only one issue of substance divides the Eastern Orthodox and the Catholic Churches, and that is the issue of the primacy." French Eastern Orthodox researcher Jean-Claude Larchet wrote that, together with the Filioque controversy, differences in interpretation of this doctrine have been and remain the primary causes of schism between the Catholic Church and the Eastern Orthodox Church. In the Eastern Orthodox churches, some understand the primacy of the bishop of Rome to be merely one of greater honour, regarding him as primus inter pares ("first among equals"), without effective power over other churches. A prominent 20th century Eastern Orthodox Christian theologian, Fr. Alexander Schmemann, envisioned a primacy that sums up rather than rules over: "Primacy is power, but as power it is not different from the power of a bishop in each church. It is not a higher power but indeed the same power, only expressed, manifested, and realized by one."
