Logical arguments for existence of 'others' in Book of Mormon times

As discussed last week, the Book of Mormon doesn't mention "others" for at least two reasons: 1) the early material from Large Plates -- which may have mentioned "others" -- was not included in our English translation, and 2) the Small Plates were focused on the ethnogenesis and religious ministry of the Nephite people and would have been unconcerned with any "others" in such a narrative.

Once the Lehites arrived in the New World, Nephi, like other people in most ancient societies, divided virtually all of the inhabitants into categories of "them" and "us."

Shortly after the Nephites and Lamanites separated, for example, Jacob -- Nephi's brother -- tells us that anyone who is not a Lamanite and "those who are friendly to Nephi" were called Nephites (Jacob 1:14), whereas those who "seek to destroy the people of Nephi," were called "Lamanites" (v. 13).