Actually we teach according to conviction that we are correct - not according to the assumption that we are infallible.
Also - sola Scriptura does not teach that we have no tradition, or that we do not cosult the great theologians of the Church - we certainly do. The doctrine of sola Scriptura teaches that the Scriptures alone are God-breathed revelation, and therefore they are the highest authority for the Church with respect to faith and practice. All tradition must be compared with Scripture, and any tradition found in conflict with the Scriptures is to be rejected.
Many Catholics suppose that Sola Scriptura teaches that any man can pick up the Bible and start a church - and this is false. However - it is an understandable confusion - because obviously this is what many ignorant professing Protestants have come to actually believe. These who claim that they are Protestant, and yet do not understand what the Historic Protestant Church teaches, can hardly call themselves (in the historic sense of the term) Evangelical - let alone Protestants. The true Protestants are Reformed in their soteriology - and hold to all five solas of the Reformation. These new so called protestants from the American Arminian movement, have no place to protest against Rome, as they are equally protesting against the Historic Protestant and Reformed Faith. These are not true protestants - but rather they are seed-pickers with no coherant theology. They claim sola Scriptura, but do not understand it - they mis-represent sola fide, and they reject the doctrines of grace.
Some good websites to visit to begin to understand with accuracy - the Historic Protestant and Reformed Faith - follow the links:
monergism.com/
reformationtheology.com/
I hope the Catholics and the Protestants on this thread will take the time to do a little first hand research and find out what the doctrine of sola Scriptura actually teaches - before continuing on in such an ignorant debate. May God bless you all !