Ask a Roman Catholic why the church has authority and he points to Scripture (‘You are Peter’); ask why Scripture has authority and he points to the church which tells us so. The theologians of the Reformation and post-Reformation era rejected this position because it is circular. William Whitaker observes: ‘Surely it is a notable circle in which this argument revolves!’. John Owen argued that if we do not rest on Scripture alone then we ‘fall into the gulf and labyrinth of an endless circle, in proving two things mutually by one another, as the church by the Scripture and the Scripture by the church, in an everlasting rotation.’ He obviously did not think of an endless labyrinth as a good place to be. A circular position is unstable: it is like asking John for directions only to have him say ‘Ask James’ and then to have James say ‘Ask John’ and so on. In the end no answer is being given.
Why then has the view been propagated that the evangelical model of authority is itself circular when our forefathers have shown that such a claim actually undermines it? The argument is that ‘God proves the Bible and the Bible proves God’ but the binary formulation and the circle are mistaken. What is the Bible? It is God’s word, breathed by him. It is not an authority distinct from him but is itself the living exercise of his authority. So to say that the Bible proves God is in fact to say that God proves God. At the bottom of the evangelical view of authority is not a circle but a single first principle, a principium (Turretin). To rest upon a single principium, provided it is the right principium, is a stable basis for belief and life.
 A Disputation on Holy Scripture, iii. 11, p. 335.
 A Discourse Concerning the Holy Spirit, VI. i. 5, 4:71.