How do things get handed down to us from God? Our present world is a long way from the days that Jesus was teaching in the temple.
We can think of tradition as having both content and activity. Tradition is both teaching (which includes doctrinal and ethical statements), and an act of handing on and receiving this content.
The Content of Tradition
Examples of tradition in the New Testament are both negative and positive. For instance, Jesus rebukes religious leaders because they've made the Word of God null and void because of their "human traditions" (Mark 7:13). And Paul makes a similar reference to "human tradition" in Col. 2:8.
But Paul also uses the term positively in 2 Thess. 2:15, when he urges the Thessalonians to "stand firm and hold fast to the traditions we (Apostles) passed on to you, whether by word of mouth or by letter." And later in the letter (3:6), he warns them to "keep away from any brother who is walking in idleness and not in accord with the tradition that you received from us."
So we need to make a distinction between "human" tradition and "apostolic" tradition. We all have traditions, the question is whether they're rooted in the apostles' teaching and in Scripture, or whether they are humanly induced laws, orders, reactions to word of mouth or letters from non-believers that deter us from hearing the Word of God.
The content of Catholic tradition is doctrinal, liturgical, and ethical. What is handed on has to do with Jesus: Jesus is Lord, or Son of God, or Messiah, etc., but it's not limited to that. Tradition also refers to liturgical acts, such as passing on how the Eucharist was to be celebrated (1 Cor. 11:23). Or tradition can refer to ways of living. Paul, for example, seems to know and use a kind of ethical tradition that consists of proverb-like aphorisms (“if you have died with Christ, now live with him”; 1 Tim. 2: 11–13) to teach his hearers a way of living suitable for followers of Christ.
The Activity of Tradition
But just as important as the content handed down is the act of passing on and receiving. Like relay runners passing on a baton, or a quarterback throwing the ball that is caught by a receiver, tradition needs both transmission and reception.
The early church historian D. H. Williams has argued persuasively that "tradition" in the New Testament and early church refers not only to passing on a set of beliefs but to a dynamic transmission of an embodied way of life—handing on a living tradition (Retrieving the Tradition and Renewing Evangelicalism: A Primer for Suspicious Protestants (Grand Rapids: Eerdmans, [1999]).
This is because handing on and receiving implies a community who lives together in a community of discipleship, such as that described in Acts 2:42, where the disciples devoted themselves to "the teaching of the Apostles (didache), fellowship, the breaking of bread, and prayers." Each of these four activities constitute a way of life that is crucial to understanding the dynamics of tradition.
So Luke begins his Gospel noting that he has recorded everything that was "handed down" by the eyewitnesses: "Many have undertaken to draw up an account of the things that have been fulfilled among us, just as they were handed down to us by those who from the first were eyewitnesses and servants of the word" (Luke 1:1-2).
And Paul says over and over again that he is passing on to his readers what he has received. In 1 Cor. 15:3–5, for instance, he writes: "I delivered to you as of first importance what I also received (paralabon)." And in 1 Cor. 11:23 he passes on the "words on institution" that he'd received ("on the night he was betrayed, Jesus took bread, broke it...") in a remarkably similar way to that recorded by Luke (22:19-20).
J.
I. Packer and Gary Parrett stress that this act of "traditioning" is
one of the key facets of catechesis. If the catechist is the one who
"hands on," the catechumen is one who "receives." They write: "all who
engage in the ministry of catechizing others are continually exercised
in both directions—they pass on what they have received. Catechesis,
then, is not concerned with novelty—certainly not in terms of content.
It is concerned, rather, with faithfulness in both learning and teaching
the things of God" (Grounded in the Gospel, 42).