Sola Scriptura
The Council of Trent in the 16th century declared that the revelation of God was not contained solely in the Scriptures. It declared that it was contained partly in the written Scriptures and partly in oral tradition and, therefore, the Scriptures were not materially sufficient.
It was neither grounded in scripture or in the church tradition, ironically.
Here is a quick definitional statement of sola scriptura as held by the Church until Trent.
"The Bible claims to be the sole and sufficient rule of faith for the Christian Church. The Scriptures are not in need of any supplement. Their authority comes from their nature as God-breathed revelation. Their authority is not dependent upon man, Church or council. The Scriptures are self-consistent, self-interpreting, and self-authenticating. The Christian Church looks at the Scriptures as the only and sufficient rule of faith and the Church is always subject to the Word, and is constantly reformed thereby." Dr. James White
All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work. (2 Timothy 3:16-17 ESV)
Paul didn't add anything else to his list as rules of faith other than God-breathed scripture. Paul doesn't suggest you can be almost complete. He doesn't suggest that the man of God is partially equipped given the right penance, and sacramental means of grace.
Further, The Early Church Fathers (Ignatius, Polycarp, Clement, the Didache, and Barnabus) taught doctrine and defended Christianity against heresies. In doing this, their sole appeal for authority was Scripture.
"This seal have thou ever on thy mind; which now by way of summary has been touched on in its heads, and if the Lord grant, shall hereafter be set forth according to our power, with Scripture proofs. For concerning the divine and sacred Mysteries of the Faith, we ought not to deliver even the most casual remark without the Holy Scriptures: nor be drawn aside by mere probabilities and the artifices of argument. Do not then believe me because I tell thee these things, unless thou receive from the Holy Scriptures the proof of what is set forth: for this salvation, which is of our faith, is not by ingenious reasonings, but by proof from the Holy Scriptures." (Cyril of Jerusalem mid-4th century)
Read more at:
http://www.christiananswers.net/q-eden/sola-scriptura-earlychurch.html
Entire books are written on this topic, but I suggest that we focus our discussion on the evidence to and against sola. I have highlighted a short positive case.