Sola Scriptura and the Biblical Canon The basic argument of Sola Scriptura is that all Christian teachings and traditions are to be founded in and subservient to the Bible, and in nothing else. Obviously this does not mean that there are to be no Christian traditions, but rather that they are to be biblically-based.

How does this tally with the history of how the Biblical canon was formed and the criteria (tradition) according to which the canon was chosen and closed? How can this formation have been founded on the Bible, if there was no Biblical canon to start with (especially with regards to the Gospels and the NT in general)?
From a historical perspective, the texts which became canonical were those which proto-orthodox Christians accepted and based their practices and traditions upon. Therefore the practices and traditions are in keeping with books which became part of the Bible.

If you think about it some Christian traditions must predate the writing of certain texts. In 1 Corithinians 11:17-34, the Lord's supper does not seem to be introduced as a new idea so this tradition must predate the text which was later accepted as canonical. So it is the proto-orthodox ideas which are found in the Bible because they picked the texts that became canonical.

All this being said, I'm not sure that Sola Scriptura really demands that all traditions are founded on the Bible - more than they can in no way run contrary to it and that anything not in the Bible is peripheral and not necessary for salvation or holiness.

It should also be noted that what is canonical does vary e.g. the Ethiopian Orthodox Church accepts more books than the Roman Catholic Church which accepts more books than most mainline Protestant denominations.