Many areas in which mindless, sometimes bigoted debates (on both sides) take place, such as Marion doctrine, purgatory, and Papal Infallibility are actually derivative of the debate on sola scriptura.(Not all such debates are mindless, indeed these positions of the Catholic Church represent, in my view, serious error. What I mean to say is that unthinking people will immediately launch into such discussions without really knowing what they are talking about.)
Protestants claim only one source of special revelation: the Holy Scriptures. Only the Bible can bind the conscience. It does not mean that everything is in the Bible, but rather everything we need to understand our relationship with God is contained therein. The Bible is necessary and sufficient.
The Roman Catholic Church adds an additional source of special revelation, the sacred traditions of the church. Unlike Protestants traditions, Roman Catholic traditions are binding. The Bible is necessary but not sufficient.
This brings us to Trent, that historic 16th century council called in response to the Reformation. In the fourth session we read:
…seeing clearly that this truth and discipline are contained in the written books, and the unwritten traditions which, received by the Apostles from the mouth of Christ himself…Ever since Trent, "written books, and the unwritten traditions" has been interpreted as meaning some revelation comes in the scriptures and some other revelation in tradition. However, there is some interesting history here.
The original language proposed was more like [revelation] is partly in the scripture and partly in tradition. This is unambiguous, and is in fact the view of the Catholic Church ever since. However during the fourth session two Italian conferees objected to the wording on the grounds that it weakened the authority of scripture. There is no record of the ensuing debate, if there was one, and soon war broke out on the continent, ending the council. When the proceedings were published, the language had been changed from partly scripture and partly tradition to scripture and tradition, but the interpretation remained the same. The explanation given is that it was merely a stylistic change.
Perhaps it was just stylistic. However, scripture and tradition can mean redundant rather than complementary sources. For example, if I say that the basic gospel message is contained in the books of Luke and John, what I mean is that it is in either of them. They are alternative sources for the same information (insofar as the basic gospel message is concerned). That is very different from saying the message is partly in Luke and partly in John.
Is it possible that Trent did not mean to imply that tradition was a source of additional revelation, only an alternative verification of scripture? Subsequent councils affirm the partly scripture partly tradition interpretation unambiguously. Can it be that it is a result of misinterpreting Trent?