Book of Sirach Testifies to Isaian Authorship of Later Chapters of Book of Isaiah

Authorship of Isaiah

In spite of the lack of concrete evidence that any part of Isaiah ever existed without any other part as far back as the 200’s BC, the dogma of most scholarship today is that two or more individuals authored Isaiah. This perspective arose, most notably in the deistic[1] climate of 18th century Europe. J. C. Doederlein, one of the earliest to argue for a second author,[2] said explicitly that since Isaiah could not have forseen the fall of Jerusalem, the 70 year captivity, the return or Cyrus, Isaiah could not have written those chapters making such claims (e.g. chapters 40-66). Since this time, others have advanced arguments in support of dual or even multiple authorship.

Others have argued for one author, Isaiah. See e.g. the AMAIC's own arguments at http://bookofjonah.blog.com/

C. 190 BC (conventional dating), Sirach (Ecclesiasticus) refers to Isaiah as having comforted the people and predicted the future (Sirach 48:24; Isa.40:1/61:1,2). This is an ancient testimony of full Isaian authorship.