Is it possible to discover, as a doctrinal matter, whether God preserves the Bible by looking at the Bible? How can you use the Bible to determine what is the Bible? From the beginning, let's say a person does not know whether this book of scripture (Bible, Koran, or something else) sitting in front of him is entirely true and worthy of belief. Should he rely upon whether it says it is true to know it is true? Even if the book was originally 100% true, and parts of the book that said it's true are still in the book, if other parts of the book are corrupted doesn't that defeat any internal assurances that the book (or rather the book's original, uncorrupted source) is true?