Let's see if I can summarize the cardinal difficulty of sola scriptura:
Conservative/Evangelical Protestant: "Human beings aren't infallible. The Bible is infallible ... well, except for these seven deuterocanonical books (rip) ... oh, and these couple chapters of Daniel (rip) .... oh, and Matthew Chapter 16 (scribble scribble scribble) ... there, now it's infallible! You can't put absolute trust into any person, only into this book, and in my interpretation of — er, well ... uh-oh." [James R. White's version is even worse: "Hey, you take your chances and take your lumps. If I'm wrong, and you believe me ... sucks to be you."]
Liberal Protestant: "Human beings aren't infallible. But, you see, the Bible isn't infallible, either. You see, everything was written too long after the fact. We know this because the disciples were all fishermen and were illiterate, and Jesus probably was too ... in fact, who knows if he said anything the Gospels attribute to him? And all these parlor tricks, these miracles ... probably later accretions. In fact, Jesus is more of a legend than anything else. But here's what I think he taught — and if he didn't, well, he should have."
Catholic/Orthodox (St. Vincent of Lérins, Commonitory, AD 434): "Here, perhaps, someone may ask: ‘If the canon of the scriptures be perfect and in itself more than suffices for everything, why is it necessary that the authority of ecclesiastical interpretation be joined to it?’ Because, quite plainly, sacred Scripture, by reason of its own depth, is not accepted by everyone as having one and the same meaning. ... Thus, because of so many distortions of such various errors, it is highly necessary that the line of prophetic and apostolic interpretation be directed in accord with the norm of the ecclesiastical and Catholic meaning."