Old Testament manuscript reliability is based on three factors: their abundance, dating, and accuracy. Most works from antiquity survive on only a handful of manuscripts: only 7 for Plato, 8 for Thucydides, 8 for Herodotus, 10 for Caesar’s Gallic Wars, and 20 for Tacitus. Only the works of Demosthenes and Homer number into the hundreds. Yet even before 1890 a scholar named Giovanni de Rossi published 731 OT manuscripts. Since that time some 10,000 OT manuscripts were found in the Cairo Geniza, and in 1947 the Dead Sea caves at Qumran produced over 600 OT manuscripts.
Further, the Dead Sea Scrolls, containing at least fragments of all OT books except Esther, all date from before the end of the first century A.D. and some to the third century B.C. The Nash Papyrus is dated between the second century B.C. and the first century A.D.
The manuscripts’ accuracy is known from internal and external evidence. (1) It is well known that Jewish scribal reverence for Scripture led to its careful transmission. (2) Examination of duplicate passages (e.g., Pss 14 and 53) show parallel transmission. (3) The early Greek translation of the OT, the Septuagint, substantially agrees with the Hebrew manuscripts. (4) Comparison of the Samaritan Pentateuch with the same biblical books preserved within the Jewish tradition shows close similarity. (5) The Dead Sea Scrolls provide manuscripts dating a thousand years earlier than most used to establish the Hebrew text.
Comparative studies reveal word-for-word identity in 95 percent of the text. Minor variants consist mostly of slips of the pen or spelling. Only 13 small changes were discovered in the entire Dead Sea Scrolls copy of Isaiah, eight of which were known from other-ancient sources. After 1,000 years of copying, there were no changes in meaning and almost no changes in wording!