 The first concerns the need for consistency proofs. On Frege’s view, the axioms of a theory always form a collection of true thoughts; and since truth implies consistency, the consistency of a collection of axioms is never in need of demonstration. For Hilbert on the other hand, the fact that a collection of sentences is taken as axiomatic is no guarantee of truth (or of truth under a given interpretation), and a demonstration of consistency is often a crucial step in establishing the mathematical respectability of that collection of axioms.