Bucky and
Eonwe
The dispute that
Thorin refers to on the movie forum in the opening of this thread was over the meaning of the words
uruk vs.
Uruk-hai. Several people said that the two words were interchangeable. I and others pointed out that in LOTR they are not used interchangeably and that
Tolkien seemed to consistently use Uruk-hai to refer to Saurman's elite troops who were apparently a blending of humans and
orcs and who could tolerate daylight. In contrast
uruks seemed to be a perhaps more general term for the large soldier orcs in
Sauron's employ who gave little evidence of light tolerence. Those of us holding this view gave a number of direct quotations from LOTR demonstrating the use of the words in LOTR. Other people claimed that the two terms were interchangeable and gave as their evidence the fact that a number of Tolkien scholars and compendiums, as well as the appendix in Unfinished
Tales, claimed the terms were interchangeable. It was at that point that I pointed out, with backing from Aragil and others, that as a general rule of research when discussing the meaning of things in The
Hobbit and LOTR, or conflicts between The Hobbit and LOTR and posthumously published Tolkien works, the latter works are secondary sources and cannot refute the clear meaning in The Hobbit or LOTR. This of course applies even more strongly for the works and opinions of other
authors, including Tolkien's son Christopher.
This is just a matter of basic
principles of research applicable to many
fields beyond Tolkien. To further elaborate on the question, it has been pointed out many times that Tolkien was an author who nearly constantly rethought and rewrote his work. Obviously one result of this is that the meaning of words that Tolkien invented might change over time in the reworking. The Hobbit and LOTR are the only major
Middle Earth works to be published during Tolkien's lifetime with his approval. He even changed things between editions, which is certainly his right as an author. Having died before
The Silmarillion and all later
books were published, these books clearly do not have the same kind of "seal of approval" from Tolkien. As Bucky has quoted, Christopher Tolkien says in his foreward to The Slmarillion "A complete consistency (either within the Silmarillion or between it & my father's other published works) is not to be looked for."
The question was never one of "trust" as Thorin phrased it, but of which works were published in a final form by Tolkien himself and which were in essence still drafts.