Your two straw men. 1) canon 2) interpreter have nothing to do with the definition of SS.
"
Sola scriptura (
Latin ablative, "by Scripture alone") is the Christian doctrine that the
Bible is the supreme authority in all matters of doctrine and practice."
BUT, let's agree for the sake of moving the roundabout. Let's use RC canon as the norm. Here's the definition.
"
Sola scriptura (
Latin ablative, "by Scripture alone") is the Christian doctrine that the
Bible is the supreme authority in all matters of doctrine and practice."
AND, let's agree for the sake of moving the roundabout a bit further. Let's let RC Magisterium be the interpreter. Here's the definition.
"
Sola scriptura (
Latin ablative, "by Scripture alone") is the Christian doctrine that the
Bible is the supreme authority in all matters of doctrine and practice."
Can you agree? If not, why not?