I recently posted a comment (HERE) to a question about how we know which books belong in the canon (HERE).  This is why I really am not a big fan of traditional apologetics.  Issues are almost always oversimplified. I’ll give the gist of how the Catholic apologist thinks the discussion should go:

Catholic asks Protestant: “How do you know which books belong in the canon? If you say that books attest to their own authority that is circular reasoning.  The Bible is attesting to which books belong in the Bible.  Also, who is the authority attested to? Individual people?  This will lead to rampant individualism.  The only way to solve this problem is the authority of the Catholic Church.”

Protestant responds: “Oh.  You’re right I must become Catholic.  I don’t want to fall into circular reasoning.  And no, individuals do not decide which books belong in the canon.  Thank God the Catholic Church has saved me from circular reasoning and the problems of rampant individualism.”

But, let me tell you how this really goes:

Catholic asks Protestant: “How do you know which books belong in the canon? If you say that books attest to their own authority that is circular reasoning.  The Bible is attesting to which books belong in the Bible.  Also, who is the authority attested to? Individual people?  This will lead to rampant individualism.  The only way to solve this problem is the authority of the Catholic Church.”

Protestant responds: “Well, how do you learn about the authority of the Catholic Church?”

Catholic responds: “Scripture and Tradition.”

Protestant responds: “So, let me get this straight.  The Catholic Church tells us which Biblical books are authoritative and belong in the Bible.  And, the we learn about the authority of the Catholic Church from the Bible.  That seems circular.  But, then there’s Tradition.  We learn about the authority of the Catholic Church from Tradition.  But, where do we learn about the authority of Tradition?”

Catholic responds: “From the Church and scripture.”

Protestant responds: “Do I really need to go any further into the circularity of all of this?”

Catholic responds: “No, wait.  The Church attests to its own divine authority.”

Protestant responds: “To whom do Churches attest that authority?  Individuals?”

All of this is not to say that Protestant reasoning is not circular.  Folks, everyone’s reasoning is circular at some point.  No one, and I mean no one, can save you from reasoning in a circle at least sometimes.  I make no qualms about it.  I am Roman Catholic.  But, I am not Roman Catholic because it saves me from circular reasoning or because it saves me from rampant individualism (and God knows that anyone who has ever served in a Catholic parish whether lay or clergy should know this is not the case).