Inerrancy extends to statements of fact, whether scientific, historical, or geographical. The biblical writers were preserved from the errors that appear in all other books. The original Hebrew and Greek autograph copies of the Bible were inerrant. Certainly the copies of copies which have come down to us contain errors common to the craft of the copyist as do all English versions. However, with diligent study, we can ascertain the original words of the inspired writers.
Inerrancy is fundamental to the doctrine of biblical authority.
If the Bible contains mistakes, then it is unreliable as a true guide to matters of salvation. If mistakes exist in one part, mistakes may just as easily exist in another part. If the Bible is a mixture of truth and error, then it is like any other book and simply not deserving of any special attention. If the doctrine of inerrancy is not true, then the Bible lacks the very criteria and credentials necessary for authenticating its divine origin. If the biblical writers demonstrate incompetency and fallibility in matters of ordinary knowledge where uninspired humans can check their credibility, then their infallibility in all other areas is discredited.