Jewish pseudepigrapha could offer
parallels to taking Isa 40-66 as written by a different author than Isaiah but
in the name of Isaiah, which would have been assumed from chapters 1-39.
However, our concern here is Jesus and the apostles quoting particular verses
from “Isaiah” and attributing them to the prophet Isaiah. I do not consider the
pseudepigraphic writings here because their authors do not quote from or expand
on specific passages composed by ancient biblical figures in the precise way as
argued by some scholars for the anonymous authorship of Isa 40-66, though
allusions to Old Testament passages are common. Rather, pseudepigraphic works
attribute completely new and later compositions to earlier biblical characters.
Their authors attached pseudepigraphic names to “new works, rather than to
citations of existing Old Testament writings. Furthermore, some of the names
identify persons who wrote nothing of which we know (e.g., Enoch, Abraham,
Jacob, etc.) Isaiah presents a different case. Those who argue for multiple
authors contend that chs. 40-66 were composed by a school of disciples or
editors who expanded on chs. 1-39, which were written by the historical Isaiah.
Indeed, it seems the large collection of pseudepigraphic works were not
included in the Old Testament canon because people likely knew at least by the
time of the close of the Old Testament canon that they were not written by the
biblical person whose name was attached to them, and thus concluded that these
compositions lacked the authority of those composed by the Old Testament
writers. Most scholars who recognize two or three Isaiahs believe that chs.
40-66 were written in the sixth century BCE, long before the literary genre of
Jewish pseudepigrapha arose and flourished (the beginning of the second century
BCE). Furthermore, if Isa 40-66 were pseudepigraphic, the author should have
inserted the name of Isaiha at various points in these chapters, as happened
typically in the pseudepigraphal books. (G. K. Beale, “’Isaiah the Prophet
Said’: The Authorship of Isaiah Reexamined in the Light of Early Jewish and
Christian Writings,” in Bind Up the Testimony: Explorations in the Genesis
of the Book of Isaiah, ed. Daniel I. Block and Richard L. Schultz [Peabody,
Mass.: Hendrickson, 2015], 96 n. 32)