“In present day usage the term commonly denotes unwritten doctrines handed down orally in the Church. It is therefore often contrasted with Scriptures. However, a remarkable scholarly consensus shows that in the early church, Scripture and Tradition were in no way exclusive concepts because they coincided with each other completely.
The concept of “tradition” when used by these [apostolic] fathers, is simply used to designate the body of doctrine which was committed to the Church by the Lord and His Apostles, whether through verbal or written communication. The body of doctrine, however, was essentially identical regardless of how it was communicated. No evidence suggests that the apostolic fathers believed they had recourse to any type of secret oral traditions. At this point in the Church’s history, Scripture and the Christian tradition were coinherent concepts…”
(The Shape of Sola Scriptura, by Mathison, 19, 21)