Either the Bible is the final authority, or the Catholic magisterium is. By definition, there cannot be two “final authorities.” To assert that the Bible is not the final authority is to assert that it is incomplete. To assert that it is incomplete is to assert that it is imperfect, since if it is perfect than nothing more can be added to it to make it “more perfect.” Finally, if the Bible is God’s divinely inspired word, then to assert that it is imperfect is to assert that God’s word is imperfect.
Which is the final authority? The Constitution or the Supreme Court which interprets it?
The Bible is materially sufficient, but not formally sufficient. The following will help you navigate that issue:
MATERIAL AND FORMAL SUFFICIENCY
By JAMES AKIN
catholic.com/thisrock/1993/9310fea2sb2.asp
MANY Protestants, including James White, have difficulty understanding the Catholic distinction between the material and the formal sufficiency of Scripture. For Scripture to be materially sufficient, it would have to contain or imply all that is needed for salvation. For it to be formally sufficient, it would not only have to contain all of this data, but it would have to be so clear that it does not need any outside information to interpret it.
Protestants call the idea that Scripture is clear the perspicuity of Scripture. Their doctrine of sola scriptura combines the perspicuity of Scripture with the claim that Scripture contains all the theological data we need.
It is important to make these distinctions because, while a Catholic cannot assert the formal sufficiency (perspicuity) of Scripture, he can assert its material sufficiency, as has been done by such well-known Catholic theologians as John Henry Newman, Walter Kaspar, George Tarvard, Henri de Lubac, Matthias Scheeben, Michael Schmaus, and Joseph Ratzinger.
French theologian Yves Congar states, “[W]e can admit sola scriptura in the sense of a material sufficiency of canonical Scripture. This means that Scripture contains, in one way or another, all truths necessary for salvation. This position can claim the support of many Fathers and early theologians. It has been, and still is, held by many modern theologians.” . . . [At Trent] it was widely . . . admitted that all the truths necessary to salvation are at least outlined in Scripture. . . . [W]e find fully verified the formula of men like Newman and Kuhn: Totum in Scriptura, totum in Traditione,
All is in Scripture, all is in Tradition.' .. Written’ and `unwritten’ indicate not so much two material domains as two modes or states of knowledge" (Tradition and Traditions [New York: Macmillian, 1967], 410-414).
This is important for a discussion of sola scriptura because many Protestants attempt to prove their doctrine by asserting the material sufficiency of Scripture. That is a move which does no good because a Catholic can agree with material sufficiency. In order to prove sola scriptura a Protestant must prove the different and much stronger claim that Scripture is so clear that no outside information or authority is needed in order to interpret it. In the debate [between Patrick Madrid and James White on sola scriptura] James White apparently failed to grasp this point and was unable to come up with answers to the charge that his arguments were geared only toward proving material sufficiency.