This is from Past Elder's Reply here.
I don't think sola scriptura is so much a complex position as it is a phrase used to mean several positions, some of which Lutherans reject and never meant.
Sola scriptura does not mean "only Scripture". It is a type of construction in Latin called an ablative of means, a way to state the means by which an agent does an action. It is translated "by Scripture alone". It does not mean, if you have Scripture you don't need anything else.
It also does not mean. if it ain't in the Bible we ain't doing it. There are those later in the Reformation to whom it does mean that, and many in our time likewise, and we reject that. For example, liturgy. Nowhere in the Bible does Jesus set up a liturgy or ask anyone else to do so. That does not mean then that having a liturgy is against the Bible. Liturgy is something the church has adopted and adapted from the synagogue because of its benefit to the good order of the church, and good order in the church is a good reason to do something.
So what we mean is, there are many good reasons for the church doing this and not doing that, and as to those which are not laid out specifically in the Bible, we accept them, we for example again accept liturgy, not rejecting it because it isn't in the Bible, but only that which has crept into it that contradicts the Bible.
You can say then our position is, if it contradicts the Bible we ain't doing it. Something being in the Bible is not the only good reason for doing it, it is rather the only good reason with a divine guarantee. And our other good reasons must not contradict those good reasons that have that divine guarantee of Scripture.
Similarly church. Sola scriptura does not reject church at all, or that church grows and develops. It rejects, rather, those things that have come along with the church's growth and development that contradict what's in the Bible. One such would be some of the Roman church's ideas as to the nature and extent of its authority. And, if these are indeed contrary to Scripture, one does not reject the church, but in fact upholds it, to deny them.
You can say then our position is, the church has said these are the books and no other on which you can rely and on whose truths the church is built, then it quit relying on them and its truths as the norm for all else, and we simply recall the church to fidelity to its own book that it declares faithful to God's truth.