Dating the old testament
The theory of Deutero-Isaiahemerged near the end of the eighteenth century.
According to this theory, Isaiah himself wrote only the first 39 chapters, leaving one of his students to pen the second part (chapters 40-66) after the Babylonian captivity started (so, after 586 BC).
It claims the second part of the second part of Isaiah was written later because only a later date can explain the accuracy of the prophecy. A long list of arguments includes the similarity of writing styles in both sections, the consistent use of the same words throughout, and the familiarity of author is with Palestine, but not Babylon.The case for an early date includes the detailed knowledge of sixth century BC events not known by a later author, various archaeological discoveries that confirm the names of characters/kings in the book, the use of early Aramaic language by the author and the similarity of theology between Daniel and the other books of the Old Testament written in the 700-500 BC period.Ezekiel, the sixth century prophet known to be a contemporary of Daniel, refers to Daniel three times in his book (Ezekiel , and 28:3) and these references are convincing evidence for the traditional view. The question of authorship is no simpler in the remainder of the OT.Talmudic traditions do link some books to well-known Biblical figures, yet most of the books do not directly identify their writers, and there is no unambiguous external evidence of authorship.
The scope of this book does not allow an extensive examination of the issues of authorship and dating of each book Old Testament book. We will, however, discuss the case for authorship and dating for the most disputed and vigorously attacked books: the Pentateuch-Torah and the prophets Isaiah and Daniel. The author of the Pentateuch is not unambiguously identified.