I have been re-reading Michael Horton's People and Place: A Covenant Ecclesiology, and I came across some good stuff on the canon that may prove to be good fodder for discussion:
Though usually advertised as a shift away from modern individualism, the drift toward assimilating soteriology to ecclesiology, justification to the church and its virtuous practices, and the word to ecclesial interpretation is more aptly described as a shift away from God's redeeming work to our own. To ask what consistutes the unity of the church, then, is to inquire as to what creates the church itself. The answer to both is the Word of God, both as means of grace and canonical norm. The gospel does not depend on reason, politics, marketing, or even on the church; it creates its own rationality, polis, publicity, and church. The gospel is self-sufficient, pulling everything else behind it.
This raises the critical issue at the heart or protests new and old against sola scriptura: the logical priority of canon and church. The sufficiency of Scripture is not an abstract, predogmatic rule but is intrinsically related to our view of God, the covenant, and redemption. Just as creation is the result of a conversation between the persons of the Trinity, the church is the offspring rather than the origin of the gospel. It is no wonder then that Paul compares the work of the gospel to God's word in creation (Rom. 4:16-17). While the covenant community is temporally prior to the inscripturated canon, the word that creates ex nihilo asserts its temporal and communicative priority over both.... The script has priority over even its most significant performances. Furthermore, the canon not only judges our poor performances but also liberates us from having to repeat or defend them.
The covenantal context proves its value once more when considering the claim that the church created the canon. God's word spoken has now also been committed to writing, a canon or consitution. The Bible is the textual deposit of God's unfading Word, whose oral proclamation had all along been creating and sustaining a church in the world since the protevangelium of Genesis 3:15. The church is not purpose-driven, but promise-driven.
Ecclesiastical authority derives from and is qualified and measured by its constiting norm: because we have this covenantal consitution, we are this particular covenant community. Thus, the priority of canon over church is the corrolary of the priority of God's grace over "human will or exertion" (Rom. 9:16).
Germinating around its nucleus of Christ's words and deeds, this canon--at first proclaimed, heard, and recalled--became a completed deposit and was treated as such long before the list of canonical books was officially prescribed in response to spurious texts.
"Theology is not free speech but holy speech," notes Webster. "Hence the authority of Scripture is a matter for the church's acknowledgement, not its ascription." ... Webster says that the solo verbo [by the Word alone] is the correlate of the sola fide [through faith alone]. To give priority to the Word is to give priority to the action of God.
As the ecclesial body cannot be equated with its sovereign head, ecclesial speech (tradition) cannot be equated with God's Word. Since Christ's person and work--and apostolic testimony to it--are qualitatively distinguished from the church and its practices, the canon does not simply offer us a good story to complete by imitation (a corrolary of the exemplary view of the atonement) or repeat by further acts of atonement and reconciliation, but a completed script that draws us into its story line as performers. The canonical characters are in a qualitatively different class than the postcanonical church that performs the play.
As in the secular polis, so in the covenant community: the distinction between the consistution (text) and the courts (interpretation) preserves us from reducing ecclesial speech to solipsism: the arbitrary exercise of power based on the church talking to itself. Yet there are still the courts. We read the Bible together, and our communaal interpretations--in the form of creeds, confessions, catechisms, and church orders--have a binding, though secondary, authority. Just as the extraordinary vocation of prophets and apostles is qualitatively distinguished from the ordinary calling of ministers today, the magisterial authority of the canon must take precedence over the ministerial authority of the church.