Although Jewish and Christian traditions, dating all the way back to the 1st millennium BC, all indicate that the 8th century prophet Isaiah wrote the book with his name on it, many modern biblical scholars claim that two, three, or even more authors actually contributed to the book over a period of several centuries.
The most popular theory, according to Walt Kaiser and Duane Garrett in the NIV Archaeological Study Bible
The first was Isaiah (1: 1), the eighth-century B.C. prophet. Called ‘First Isaiah’ or ‘Proto-Isaiah,’ he is thought to have produced the core of chapters 1– 39. ‘Second’ or ‘Deutero-Isaiah’ is assumed to have been an anonymous prophet of the sixth century B.C., to whom are attributed chapters 40– 55. Another postexilic prophet, ‘Third’ or ‘Trito-Isaiah,’ is posited to have composed most of chapters 56– 66, perhaps around 400 B.C.
What arguments and evidence do Trito-Isaiah advocates offer to convince us their position is correct?
Advocates of this theory attempt to demonstrate that the style, theology and background of Isaiah 1– 39 are unlike those of either 40– 55 or 56– 66. Second Isaiah— but not First— they argue, depicts God in purely monotheistic terms. Also, First Isaiah is seen as a prophet of judgment, who placed his hopes on the Davidic king, and Second Isaiah a prophet of comfort who pinned his expectations on the Lord’s suffering servant.
More substantial are the arguments focusing on the backgrounds of the respective chapters. The Old Testament prophets in general are widely understood to have written from their own unique historical situations. Even if one acknowledges that Isaiah could have predicted the Babylonian captivity, it is argued, it is unlikely that he wrote chapters 40– 55, since those texts were written from within the context of captivity. Also, the Persian king Cyrus (c. 539 B.C.) is mentioned by name in 44: 28 and 45: 1, 13, suggesting that Cyrus was a contemporary of the author of chapters 40– 55. The background of Third Isaiah is posited to be different again. By this point Jerusalem had been rebuilt, its citizens no longer under threat from either Assyria or Babylon.
How do critics of Trito-Isaiah respond?
An author’s style depends upon a variety of factors (age, purpose, subject matter, audience, etc.), and stylistic factors like vocabulary are apt to change.
The three ‘Isaiahs’ do share many phrases and words, suggesting stylistic unity. For example, God is called the ‘Holy One of Israel’ throughout (e.g., 10: 17; 41: 14; 60: 9).
The alleged theological differences are artificial. Isaiah is a lengthy book, but it does not incorporate any real internal tension or overt contradiction.
All of Isaiah is concerned with Canaanite idolatry. While scholars would expect such a focus from First Isaiah, they would not anticipate it in Second or Third Isaiah (e.g., 57: 13); it was not a significant issue to postexilic prophets such as Zechariah, Haggai and Malachi.
From early on Isaiah promised that the Gentiles would submit to the God of Israel (e.g., 2: 2– 4), an expectation developed throughout the book (e.g., 42: 4; 49: 6) and a unifying theological motif for the whole of Isaiah.
What about the historical perspective and predictions of Isaiah?
Isaiah did project himself into the future to describe events as though they had already occurred (e.g., 5: 13– 17; 9: 1– 7; 23: 1, 14). In fact, Isaiah 6, a foundational chapter, presents the exile as inevitable. Isaiah assumed that exile was certain and wrote chapters 40– 55 with that in mind.
Isaiah’s mention of Cyrus’s name has a parallel in the prediction of Josiah’s name in 1 Kings 13: 2. It is true that predictions of this kind are fairly rare in the Old Testament, but they do occur.
In contrast to Ezekiel, who lived in Babylon, ‘Second Isaiah’ gave no indication at all that he was familiar with life in Babylon. This suggests that the author of Isaiah 40– 55 did not in fact experience Babylonian exile— which is just what we would expect if the chapters were written by Isaiah of Jerusalem.
Finally, Kaiser and Garrett note that the “only related archaeological evidence comes from a Dead Sea Scroll designated 1QIsaa. This nearly complete text of Isaiah confirms the conservative position in that there is no break between chapters 39 and 40.”