Written by Persons Unknown

• Open-set nearest shrunken centroid methods show that the Book of Mormon was not written by any of the proposed 19th century authors--at least not without some unexplained (and likely unprecedented) amount of disguising or modification of style.
• Schaalje and Fields extended the numbers of stylometric features by including not only 74 of the noncontextual words used by Jockers et al. (removing contextual words retained by Jockers et al.), but also two of the vocabulary richness features used by Holmes, and a number of noncontextual word pairings used by Hilton and coworkers. As we learned from the adversarial authorship studies, increasing the number of features studied improves our chances of identifying the correct author.
• Just like the Holmes and Jockers et al. studies, the data of Schaalje and Fields clearly support multiple authorship for the Book of Mormon. 

In the last post we saw how, if a text is written by an unknown author, the stylometric features usually don't line up with the candidate authors in a study. Schaalje and Fields looked at the Book of Mormon texts several different ways. They simply cut the Book of Mormon text into 2000 word chunks. They divided it like by chapter, just like Jockers et al. They compared it with the writings of Rigdon, Cowdery, Spalding, Pratt, and Smith. They pretended they 2 of these 5 authors were unknown and tested those 2 authors and the Book of Mormon texts against the 3 remaining authors. Every single time the Book of Mormon came up as different from the test authors. Here is a summary figure for the comparison with 2000 word chunks of text:

Apparently Jockers et al. had the data to figure out they were mostly measuring false positives right in front of them. Besides using the NSC method, they also used a method called Delta. One of the originators of this method determined empirically that Delta values between 0 and -1.9 were most likely false positives. Schaalje and Fields reproduced the Delta calculations of Jockers et al. and produced this graph:

You will notice that only 16 of the 239 chapters are higher than 1.9 (the graph made everything positive), and 10 of those are quotes from Isaiah and Malachi. That's over 93% likely false positives. Oops. The fact that Delta agreed significantly with their closed-set NSC results did tell them something--just not what they claimed it did.

The most interesting of the Schaalje and Fields figures for us Book of Mormon aficionados is this one:

You can see that Isaiah/Malachi significantly overlaps a small portion of the Book of Mormon chapters. Late Sidney Rigdon overlaps a few. You can also see that almost all of the Book of Mormon chapters are different in style from any of the candidate authors--and that's only looking at the first two principle components. Adding additional principle components would only emphasize differences further. In addition, this plot gives another representation of how much each individual author's style varies. When you draw boundaries around each author's samples you get areas that are roughly comparable in size. Some are bigger, some are smaller. None of them are close to the size of variation we see in the Book of Mormon samples. If the Book of Mormon were written only by authors whose styles had zero overlap, these data would indicate at least 4 or 5 different authors, even allowing for style to change with age of the author. If we allow for overlap like what is seen for the five 19th century authors, the Book of Mormon could easily have been written by 20 authors. Schaalje and Fields don't make that claim in either of these peer reviewed papers, it's not what the method was looking for, but we don't have to be geniuses to see it ourselves.

Recap

• We've looked at studies from three different research groups. 
• Two groups were critical of LDS claims of Book of Mormon authorship. One group was pro-LDS authorship claims. 
• The results of all three groups support multiple authorship for the Book of Mormon.
• None of the groups support viewing Joseph Smith as a primary author of the Book of Mormon (although vocabulary richness gives limited overlap between the Book of Mormon and the Doctrine and Covenants).
• Vocabulary richness tentatively distinguishes styles for Nephi, Lehi, Abraham, and Alma/Mormon, and maybe others based on the first 3 principle components.

That's a pretty clear picture forming, whatever the rhetoric put forward in the background and conclusions sections of the various papers. It looks like two possibilities remain for rational critics of Joseph Smith's authorship hypothesis, namely, multiple non-19th century authors. The first comes from adversarial authorship studies. It is possible for some authors to change and disguise their styles according to a wide variety of measures. If critics could show historical evidence of Joseph Smith having attempted to do this that dates to close to 1830, that would be telling. It would be best if they could show that he was trying to imitate specific authors. Maybe comparing styles in the Book of Mormon with styles of specific books in the King James Bible would be good test, or with some of the books found by the Johnson's to have linguistic similarities with the Book of Mormon. Authors did best at disguising their style if they were imitating someone else, so if different voices in the Book of Mormon matched different, non-candidate voices from the 19th century, that would be telling. If they could show another author who has successfully created a book with such a wide variety of statistical authorship styles as is found in the Book of Mormon, that would be telling, too, even if it weren't proof. If they could even write a book of similar length with as wide a variety of styles, that would be something. If they could find a single authored book with this variety of styles then at least the Book of Mormon wouldn't be unique. Based on the data so far, single authorship and 19th century candidate authorship are really extraordinary claims in need of evidence.

The second alternative, although somewhat tenuous, was put forth by Jockers et al. Maybe the text is collaborative from the 19th century. Unfortunately for critics (please remember not to include Jockers among them--he really doesn't care), they need to provide solid control data for what collaboration does to style. Then they need to show that collaboration can shift style so that it is unrecognizable as belonging to either of the collaborators, and that it can spread the styles out to look like at least four or five completely distinct authors. Collaboration is still a possible explanation, as is disguised and varied styles created by Joseph Smith. It seems, however, that examples of single or dual author texts with stylometric features like the Book of Mormon are as rare as angels and gold plates--maybe more.