What Proves The Authority Of Scripture?

The Bible is constantly under attack these days and its authority is often rejected.  Liberal scholars and sometimes evangelical scholars express doubt about the trustworthiness of Scripture.  So how can the authority of Scripture be proven?  

Biblical Christians believe that the Bible is the ultimate authority.  If something is an ultimate authority it cannot be proven by a lesser authority.  The Bible is the Word of God so it cannot be authenticated by the word of man.  There is no authority outside of Scripture that can prove its authority.  Ultimately the Bible is self authenticating, it proves itself as the Word of God.  Since Scripture is the ultimate authority it must be appealed to in order to prove its own authority.  

But what about evidences, proofs, and arguments?  All of these can be helpful and do provide support for the authority of Scripture but they cannot offer ultimate proof of its authority.  All of these would involve appealing to a lesser authority to validate Scripture which is the ultimate authority.  

We can see some weaknesses in evidentialism and classical apologetics.  They both end up appealing to a lesser authority to prove Scripture as the ultimate authority.  They start with the premise that the Bible cannot be used in apologetics.  So in order to defend the Bible we must set it aside and not use it.  This makes no sense whatsoever.  They believe we should start on a neutral ground with the unbeliever.  Quite frankly this is simply not Biblical apologetics.  

In reality there is no neutral ground to start on with the unbeliever.  Everyone operates with basic presuppositions or assumptions.  All people start with the assumption that Scripture is authoritative or it is not authoritative.  This then shapes how one views evidences and arguments that are presented.  The strength of presuppositional apologetics is that it actually uses the Bible to defend the Bible.

Ultimately the Holy Spirit must open a person's heart and mind to the truth of the Bible.  Scripture is self attesting or self authenticating, it depends on no outside authority.  But is claiming that the Bible proves itself as authoritative a circular argument?  To a certain degree all arguments for an ultimate authority involve circular reasoning.  For example one who holds that reason is the ultimate authority must use reason to prove it.  Only presupposing the authority of Scripture leads to truth and reality.