If you’ve never heard of the Deutero-Isaiah hypothesis, it’s the modern belief Isaiah didn’t write the book bearing his name — actually multiple authors wrote parts and those anonymous authors became compiled much later into one book called Isaiah. Most commonly, the theory states two authors wrote the book (less commonly, three authors) as web sites about the theory frequently state:
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 climate of 18th century Europe. J. C. Doederlein, one of the earliest to argue for a second author, 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.
Since the middle chapters (40–66) have a style different from the rest of the book, the theory holds multiple authors wrote under the Isaiah name. If you Google for “Deutero-Isaiah Hypothesis” you’ll find many links, and even books promoting this “scholarly” view.
This is the critical issue — so many scholars have so many theories (each with hundreds of pages of dissertation), what should a person do? The problem arises as many of these theories cause people to fall away from faith, and fail to check out the so-called scholarship for themselves (after all, who wants to read hundreds of pages of boring PhD thesis?). But of course, that assumes the validity of their theory — don’t fall for the lie the PhD’s behind their scholarly writing implies their bloviating has any truth whatsoever.
In the case of the Deutero-Isaiah hypothesis, it’s pure junk as the Gospel of John reveals.
But though he had done so many miracles before them, yet they believed not on him; That the saying of Isaiah the prophet might be fulfilled, which he spoke, Lord, who hath believed our report? And to whom hath the arm of the Lord been revealed? (John 12:37–38 KJV)
A simple quote in John’s gospel. Almost every Bible (and many readers) recognize the quote as from Isaiah:
Who hath believed our report? And to whom is the arm of the Lord revealed? (Isaiah 53:1 KJV)
Simple so far, but keep reading in John:
He hath blinded their eyes, and hardened their heart; that they should not see with their eyes, nor understand with their heart, and be converted, and I should heal them. These things said Isaiah, when he saw his glory, and spoke of him. (John 12:40–41 KJV)
Not as many people recognize that quote, but it’s from Isaiah 6:
And he said, Go, and tell this people, Hear ye indeed, but understand not; and see ye indeed, but perceive not. Make the heart of this people fat, and make their ears heavy, and shut their eyes; lest they see with their eyes, and hear with their ears, and understand with their heart, and convert, and be healed. (Isaiah 6:9–10 KJV)
So we’ve got quotes from both “halves” of Isaiah — chapter six and fifty-three. But who wrote them? Should we return to the Deutero-Isaiah hypotheses and spend hours in boring research? Don’t fret over the authorship of Isaiah, as in between John 12:38 and John 12:40 is verse 39:
Therefore they could not believe, because that Isaiah said again, (John 12:39 KJV)
Oops. John quotes from both “halves” of Isaiah, and attributes them to Isaiah. So who wrote Isaiah (all of it)? Isaiah. You don’t need to waste hours reading hundreds of pages of so-called “scholarship” — John just told you who wrote Isaiah. If you believe the inspiration of John as he wrote the authorship of Isaiah is settled (if you don’t believe in the inspiration of the Holy Spirit and the inerrancy of the Bible you’ve frankly got much bigger issues than the authorship of Isaiah).
And thus you can toss the Deutero-Isaiah hypothesis onto the scrap-heap of pseudo-scholarship once and for all. Don’t waste your time with it — it doesn’t matter if someone wrote 500 pages espousing the scholarship, it’s a useless and contradictory position you don’t need to waste your time with — all the Deutero-Isaiah hypothesis proves is someone hasn’t read the book they claim to be an expert on.
Just read the book, many times it destroys the so-called “scholarship” of people claiming to be experts in the book, but in reality simply failing to read (and understand) the whole of it.