Within the broad tradition of Eastern Orthodoxy, how is tradition viewed? Is it authoritative? If so, what parts? What about when Church fathers contradict each other in teaching? Which church father is chosen as authoritative over the other and who has the authority to do this?
In its early centuries Eastern Orthodoxy based tradition on the authority of bishops, based on the principle of apostolic succession. Tradition is rooted in dogma, again based on the teaching authority of the bishops.
"Do nothing without the bishop," Ignatius of Antioch wrote (Trallians 2.2). Both the Roman church and the future Eastern Orthodox churches agreed that the authoritative teaching tradition resided in the bishops, who also held the authority to decide on customs as well as dogma. The idea is that there is an unbroken chain of authority handed down from the disciples to the bishops through the charism of laying-on of hands. (See Apostolic Succession for a summary of this concept from the Orthodox viewpoint).
But both bishops and Church Fathers sometimes disagreed on important issues. This led to the Orthodox insistence that when the authority of bishops is divided, Ecumenical Councils will decide the issue. The Orthodox tradition originally recognized the Bishop of Rome as the "first among equals" but did not grant him superior authority on issues of dogma and practice. Today the title of Primus inter Pares is given to the Ecumenical Patriarch of Constantinople.
The role of Ecumenical Councils is extremely important to the Orthodox regarding the tradition of creeds. Changes in creedal formulas must not be decided either by regional councils or by popes. However this also relates to issues such as holiday dates, liturgy, married clergy, etc.
Traditions not covered by Holy Dogma are called "customs" and may vary from place to place, depending on the rulings of the metropolitan bishops, patriarchs, local councils and local bishops.
- In minor things—the style of vestments, the exact order of services, customs associated with various feast days—there is a wide variety of customs which may be found, as developed in various times and various places based on a wide variety of circumstances. Furthermore, these customs are not, nor were they ever intended to be, that which brings about unity within the Church.
To summarize, in Eastern Orthodoxy, tradition is intimately related to dogma, which is ultimately decided by Ecumenical Councils. However, "customs" may vary widely.
Regarding the question of which Church Fathers hold the greatest authority, this is too large a matter to answer in detail here. Since the time of the late 2nd century or so, the Eastern churches tended to appeal more to those Fathers who wrote in Greek, while the Roman Church appealed more to those who wrote in Latin. Thus, authorities such as Tertullian, Jerome and Augustine, so important to the Western church, are less so in the East. Conversely, John Chrysostom, the Cappadocian Fathers and the Desert Fathers are more important in the East than the West.