Twenty-One Councils From Nicaea to Vatican II

An ecumenical council, in the Catholic Church's own definition, is a gathering of bishops from the whole church whose decisions bind on faith and morals once the bishop of Rome has summoned it, presided over it in person or by legate, or confirmed its acts afterward. On that criterion the church counts twenty-one such councils, beginning with Nicaea in 325 and running, after a gap of nearly a century since the last council both East and West accepted, to the Second Vatican Council, which met from 1962 to 1965. The count is disputed rather than universal: Eastern Orthodoxy recognizes only the first seven, those held before the eleventh century schism split the two communions, and treats papal confirmation as no part of what makes a council ecumenical in the first place, since the seven were confirmed by consensus among the ancient patriarchates rather than by Rome alone. Because Catholic teaching ties the criterion to the ongoing papal office rather than to a closed ancient list, the series has never been formally closed the way the Orthodox list has. A future council remains possible in principle, summoned or confirmed by whoever then holds the office, which is the structural reason the Catholic count keeps rising while the Orthodox count has held at seven for over a thousand years.