Many non-LDS scholars claim that the second half of the book of Isaiah was written after the time Lehi left Jerusalem, Yet the Book of Mormon contains material from both halves. How do we explain this?

L. La Mar Adams, author of several books, biblical researcher, and assistant professor of statistics, Brigham Young University.

What creates the problem for you is that most biblical scholars claim that the book of Isaiah is a compilation of the work of several authors who lived over an extended period of time. This theory originated as early as A.D. 1100 when Moses ben Samuel expressed the belief that Isaiah was not the author of certain chapters. I believe we have reason for our faith that the man Isaiah originally authored the entire book credited to his name. Lehi would therefore have taken the entire book with him when he left Jerusalem.

The problem giving birth to the multiple-authorship theory is the prophecies of Isaiah. For example, Isaiah identifies King Cyrus of Persia by name and indicates that Cyrus will set the Israelites free of Babylon. This event actually occurred many decades after Isaiah lived. To a person with a testimony of prophecy, such a pronouncement isn’t astonishing. But to a person who lacks that testimony, it’s impossible. Those who reject the existence of prophecy as we know it have no choice but to conclude that the book of Isaiah must have been written by more than one man.

A few years ago, our group of thirty-five specialists in Semitic languages, statistics, and computer science at Brigham Young University devised a literary style analysis to test the claims of these biblical scholars. This study, which spanned several years, in the end used more than 300 computer programs, analyzed several hundred stylistic variables, and obtained more than 4800 statistical comparisons.

Literary style in Hebrew is much more accessible to computer analysis than is English. This is partly because the Hebrew characteristic known as the function prefix can help identify speech patterns of a given author. For example, how an author uses Hebrew function prefixes, such as those that translate into “and in this,” “and it is,” and “and to,” are expected to be unique with him. Thus, comparing parts of an author’s work with other parts, as well as comparing his work with work by other authors, can yield statistical evidence for claims of authorship.

Accordingly, we coded the Hebrew text of the book of Isaiah and a random sampling of eleven other Old Testament books onto computer tape. Then, using a computer, we compared rates of literary usage (such as unique expressions and idiomatic phrases including the function prefix and other such literary elements) from text to text. Since any author varies within himself, depending on context, audience, his own change of style, and so forth, variations for a given author were compared with variations between authors for any literary element.

The results of the study were conclusive: there is a unique authorship style throughout the various sections of Isaiah. The rates of usage for the elements of this particular style are more consistent within the book of Isaiah, regardless of the section, than in any other book in the study. This statistical evidence led us to a single conclusion: based on style alone, the book of Isaiah definitely appears to be the work of one man. The two parts of Isaiah most often claimed to have been written by different authors, chapters 1–39 and 40–66, were found to be more similar to each other in style than to any of the other eleven Old Testament books examined.

Some scholars seem to have a desire to do away with prophecy by placing the second half of Isaiah after the events described, making the mention of those events historical rather than prophetic. But Latter-day Saints, with their testimony of prophecy and with the many evidences given in the scriptures, have long affirmed that Isaiah, son of Amoz, wrote the entire book of Isaiah. In the Book of Mormon, Jacob, Nephi, Abinadi, and Jesus all quote from different parts of Isaiah, and each identifies the prophet by name. In their Gospels in the New Testament, Matthew, Luke, and John the Beloved do the same.

No matter what evidence is available in the scriptures or more from secular sources such as computer analysis, there will undoubtedly continue to be those who will try to set the prophecies of Isaiah aside because they feel Isaiah could not know such details in advance. In this they err twice: (1) they err in thinking that Isaiah did not write chapters 40–66, and (2) they err in thinking that prophets do not know such details. The words of God’s prophets invariably come to pass.