What would be good sources for the evidence for the change in language between Prot/Deutero/Trito Isaiah in the Bible?

Question

I am very interested in understanding the biblical book of Isaiah. I have read in numerous places that virtually no modern scholars view the book as having been written only by the historical Isaiah ben Amoz of the 8th century BC but that there were at least one and probably more anonymous writers in the 6th century BC.

I am aware that Bernhard Duhm is credited with being one of the earliest scholars to provide arguments for this but I cannot find out what his actual arguments specifically were. I am aware of the differences in historical settings being part of the argument, that being that there is clearly a shift from an Assyrian/Judah perspective to a post exilic Babylonian one. I get that. But I also see references to differences in style and language but have never been able to track down any actual examples.

Is there any good commentary that specifically explains these differences in language?

Answer 1

The main argument boils down to subject matter and prophecies. In academic circles if a book prophesies about some event unambiguously then it must have been written after the event. Isaiah prophesied both about the destruction of Assyria and the babylonian captivity and the destruction of Babylon, so it must have been written after all three of these events, and the easiest notion is to break it up into three books, with Isaiah part 1 (chapter 1 - 39) focusing on Assyria as the enemy, Isaiah part 2 (40 - 55) focusing on Babylon, and Isaiah part 3 (56-66) has the Persians as enemies. Also if we divide Isaiah this way, then part 1 focuses more on judgement, part 2 on redemption, etc. E.g. not all parts have the same tone and subject matter.

But if you make this split you run into problems with similar passages and literary devices used across the parts, so then you say that there must have been an editing process in which parts of Isaiah 1 were re-written or edited to be in harmony with Isaiah part 2.

In this way, differences between sections of the text are evidence of different books, but harmony between portions of text is proof that the text needs to be broken up even more, etc.

Here is an excerpt from the preface of Hermeneia's commentary to Deutero-Isaiah (Isaiah part 2)

There are a number of reasons for distinguishing between DtIsa and Isaiah, but the different period of the historical events that form the background is particularly important. In Isaiah, Israel’s enemies are the Assyrians. Their empire was destroyed by the Neo-Babylonians and the Medes at the end of the seventh century B.C.E. For DtIsa, the antagonist is Babylon. The exile (598/597 B.C.E.) and the fall of Jerusalem (587/586 B.C.E.) are the preceding events presupposed. In Isa 44:28* and 45:1* the Persian king Cyrus II (559–530 B.C.E.) is mentioned. In addition to this disparity in historical background, there are literary differences in style and genre. The thrust of Isaiah’s theology is primarily judgment; DtIsa proclaims salvation and a new beginning. It must be said, however, that the tripartite division of the book of Isaiah into Isaiah I (chaps. 1–39), Isaiah II or Deutero-Isaiah (chaps. 40–55) and Isaiah III or Trito-Isaiah (chaps. 56–66), is no longer unquestionably accepted in research. The question of how the different parts of the book hang together is beginning to be raised once more. As H.-J. Kraus rightly puts it, this is probably not just a “bookbinding problem.” What all three parts have in common is the theme of Zion/Jerusalem. Common to them also is the entitling and concept of Israel’s God as “the Holy One”8 and “king.” There are a number of possible ways of linking the different parts of the book of Isaiah, and these have continually been discussed. C. C. Torrey, for example, assumed that Isaiah 34–35 and 40–66 were connected. C. R. Seitz has recently investigated chaps. 36–37, seeing them as a compositional link between Isaiah I and Deutero-Isaiah. There are relationships in points of detail too. Isaiah 40 would seem to presuppose Isaiah 6 (the chapter describing the installation of the prophet Isaiah) or its tradition. The presupposition in both passages is the concept of the divine council. The “oracles concerning Babylon” in Isa 13:1–14:23* and 21:1–10* play a part in the description of Babylon’s downfall in 46:1–2* and 47:1–15*.13 In DtIsa messianic expectations are transferred to Cyrus (45:1*). The literary problem of the composition of Isaiah I must undoubtedly be seen in a more differentiated way than Duhm’s formulation allows. This goes so far as to assume that the combination of Isaiah I and II had a subsequent influence on the text and structure of Isaiah I.14 For example, I too believe that Isaiah’s installation has been moved from the beginning of the prophet’s biography (which is its proper place, according to the genre) to its present position in Isaiah 6. Thus the “hardness of heart” (6:10*) also no longer comes at the beginning; instead we have Isaiah chap. 1, the people’s guilt and its consequences, and Isaiah chap. 2, the pilgrimage of the nations to Zion. Trito-Isaiah presents a special problem. I myself no longer consider the sequence Deutero-Isaiah (40–55)—Trito-Isaiah (56–66) to be self-evident. Of course the two have much in common in language and tradition. But the differences should also be noted. Isaiah 60–62 presents a description of Yahweh’s return to Zion that makes a more original, primary impression than 52:7–10*, for example, whose theme is the same. In Trito-Isaiah the tone toward foreigners is clearly more hostile. The relationship to the cult is also different. And an assimilation of penitential and confessional liturgical fragments can be detected. Here further discussion is required.

Baltzer, K. (2001). Deutero-Isaiah: a commentary on Isaiah 40–55. (P. Machinist, Ed.) (p. 1). Minneapolis, MN: Fortress Press.

I would look at all three Hermeneia commentaries to get a good overview, they have excellent bibliographies and will provide relatively modern academic viewpoints in their introductory sections to each book.

Answer 2

In addition to the comments already shared by Robert, I would share one additional thought. Isaiah can be broken into 2 pieces (ch. 1-39 & ch. 40-66) or into 3 pieces (ch. 1-39, ch. 40-55, ch. 56-66) or into even more pieces.

These divisions generally rely on either a presupposition about prophecy (I shared some thoughts on this topic on this site here) or a separation of subject matter.

If we focus on divisions by subject matter, we can either infer:

1. These are different authors who each always wrote about the same things.
2. This is one author who has written on several topics, and has organized his book by grouping the material by topic. (a writer & poet of this caliber was clearly well-read, and probably had thoughts on multiple topics)

The Occam's razor approach would be option 2, which does not multiply entities beyond necessity. It is also the approach taken by Victor Ludlow, one of the few modern scholars who does believe that Isaiah 1-66 was produced by Isaiah ben Amoz (his commentary is "Isaiah - Prophet, Seer, and Poet"). His commentary addresses Deutero & Trito Isaiah and the thoughts behind them, but ultimately concludes that these are unnecessary assumptions.