The King James Version is a translation from the original languages of the biblical text which were Hebrew and a small amount of Aramaic for the Old Testament and Greek for the New Testament. These languages, especially Hebrew and Aramaic, are very different than English in their structure. For example the the famous phrase "and it came to pass" is a single word in Hebrew consisting of only four letters: ויהי. Some other oddities are as follows. Prepositions are frequently prefixes to words and possessive pronouns are frequently suffixes. Linking verbs (is, are, be) pretty much don't exist at all. Verbs usually precede the noun which is the subject of a sentence and if the subject is a pronoun it is generally not included at all as the verb conjugation provides enough information to imply the pronoun. In prose direct objects are preceded with a special word את ('et) for which there is no English equivalent and by English speakers is just referred to as "the direct object marker."The above is only a sampling of the distinct differences between Hebrew and English and similar differences could be noted for Greek, although it is closer to English than Hebrew. You can add to that hundreds of idiomatic phrases that make little sense in literal translation. The task of the translator is not simply to render an exact meaning of the original text in English, but to capture its sense and style as truly as possible. In many cases the King James translators did an amazing job especially given the limitations on the knowledge of the original languages and cultures that produced the Bible. Some of the language used is striking and has greatly influenced our culture and literature. However any translation is subjective at times as the intent of the original writer must be interpreted to render it in English. Occasionally there is no graceful way to express the same thought in English and it is necessary to add words to clarify intent and meaning of the original. In more modern text these types of additions are made [with square brackets]. The thought of modifying or adding to scripture was a serious undertaking and there are explicit warnings on some books against doing so (Revelation 22:18-19, Deuteronomy 4:2). In an effort to clarify for the reader exactly what words were translations of the original tounges and what words were added for clarity, the translators used italics to identify the added words.
So given the purpose of the italicized words, it is a fair question to ask how much liberty did the translators take. Well for simplicity I turn to Deuteronomy 4 since it was what was open from writing the last paragraph and I will have a look at some of the verses there:
Here the translators added the word them as the phrase sounds odd in English (but not Hebrew) unless we have a direct object. Reading without the word gives the same meaning but sounds a bit more choppy to our ears. This is a good example of a word appropriately added for translation.
1 Now therefore hearken, O Israel, unto the statutes and unto the judgments, which I teach you, for to do them, that ye may live, and go in and possess the land which the Lord God of your fathers giveth you.
This is similar as well. Again the Hebrew does not need a word here and I would argue the English really doesn't either. However we have to remember that much has changed in our own language since 1611 when the KJV was published. Perhaps to them this sounded better. It could be said that adding ought implies a quantity and thus very subtly adds emphasis to the original. Try reading it with a more modern word like anything in the place there and see if the subtle change makes a difference compared to omitting the word.
2 Ye shall not add unto the word which I command you, neither shall ye diminish ought from it, that ye may keep the commandments of the Lord your God which I command you.
Here as we discussed is the addition of a linking verb that does not exist in Hebrew. This is a normal and needed part of translation. I will say however that the use of italics on linking verbs as well as on the preposition of is inconsistent throughout the text. I am unaware of what logic was used to decide to italicize the addition in a verse like this but in many other verses it is not italicized even though added by necessity.
4 But ye that did cleave unto the Lord your God are alive every one of you this day.
This verse combines the linking verb issues as well as the direct object issue discussed above.
6 Keep therefore and do them; for this is your wisdom and your understanding in the sight of the nations, which shall hear all these statutes, and say, Surely this great nation is a wise and understanding people.
This rhetorical question has a lot of additions. This is not a bad thing as Hebrew comparative statements are very idiomatic and require less words than English to express the thought. I do like the addition of the preposition added at the end of the sentence. I strongly suspect this was a way for the original translators to scripturally thumb their noses at their high school English teachers.
7 For what nation is there so great, who hath God so nigh unto them, as the Lord our God is in all things that we call upon him for?
Here the translators have taken a bit more liberty. There is a bit of a disjoin in thought between this phrase and the one that precedes it. This verse actually acts as an apposition to the the term "these things which thine eyes have seen" from verse 9. The translators have added the word specially to make the verses flow better but adding this word tends to subtly change the meaning, suggesting the "day thou stoodest before the Lord" was a special portion of several things "thine eyes have seen" that were to be taught to the sons rather than an explanation of the very experience the command refers to. Perhaps specifically would have been a better choice of a fill word here. This difference is subtle and it would be difficult to suggest it makes any doctrinal impact on the interpretation.
10 Specially the day that thou stoodest before the Lord thy God in Horeb, when the Lord said unto me, Gather me the people together, and I will make them hear my words, that they may learn to fear me all the days that they shall live upon the earth, and that they may teach their children.
Here the translators must have felt there may have been confusion over possibly seeing a voice and felt the need to add an extra verb for clarity. Personally I think it could read better without it.
12 And the Lord spake unto you out of the midst of the fire: ye heard the voice of the words, but saw no similitude; only ye heard a voice.
As you can see these are all very minor concerns and most are made with the best intentions of clarity. I want to look at a handful of examples that go a bit further, where the translators are clearly amending the text to suit a predefined agenda. Consider Psalms 7:11 :
Psalm 7 is a difficult psalm in general. The subject of the verses jumps around quite a bit sometimes referring to God sometimes to the wicked and with this in mind the translators were attempting to construct a a narrative that made sense theologically. However even with the best of intentions the addition of an explanatory note identifying who God is angry with seems a step too far from translator to interpretor. This remains true even though I agree with their conclusion. It prevents readers from forming their own interpretation based on the actual text of the verse and forces a specific reading.
11 God judgeth the righteous, and God is angry with the wicked every day.
Consider also 2 Samuel 21:19:
Here the verse directly contradicts the other major story line in Samuel. The translators felt it was important to not bicker and argue over who killed who and added a bit of text the brother of to make the whole story consistent. Now in fairness the text was probably corrupted at some point and probably should have said something like this. It is pieced together from 1 Samuel 17:49, 1 Samuel 21:9, and 1 Chronicles 20:5. But is it really within the right of a translator to correct a text to read as a story that is free from contradiction or should the reader be forced to deal with the contradictions of the ancient text? Can we not suppose that God gives us problematic texts for a reason?
19 And there was again a battle in Gob with the Philistines, where Elhanan the son of Jaare-oregim, a Beth-lehemite, slew the brother of Goliath the Gittite, the staff of whose spear was like a weaver’s beam.
A concise explanation of this is whole situation is found in the Bible Dictionary for the LDS edition of the scriptures under the heading of Italics where it concludes that "generally, though not always" the judgement of the translators was sound.
So it should become obvious by now that many of the techniques used by the KJV translators were also used by Joseph Smith in his inspired translation of the scriptures. Certainly the techniques used by Joseph were different as they relied on inspiration rather than scholarship and were far more extensive, though much more focused on specific passages, yet the outcome was the same. Words were supplied to enhance the text, iron out contradictions, and conform to a doctrinal agenda. The difference was a matter of authority. Joseph as a fully authorized prophet of God had the authority to create new scripture and edit and restore existing scripture to comply with revealed doctrines. It does not escape me that a large swath of mainstream Christianity condemns Joseph's translation as altering the Bible while defending the KJV to extreme levels as being a perfect translation. I find this an odd position as the translators themselves would not have asserted the infallibility of their work and claimed no special authority from God, yet they performed many of the same functions that Joseph did with his translation.
In conclusion I want to affirm my deep respect for the KJV and its translators. I am especially impressed with their transparency in providing a clear indicator in their text to identify to the reader where they have used interpretive license by using italics. Theirs is a work that deserves its honored place in our English LDS scriptures but it should not be viewed as a perfect translation, or the final word in doctrinal matters. The scriptures produced by Joseph Smith and other modern prophets have the special status of being a product of an authorized translator rather than simply the work of scholars. Even still, Joseph never claimed perfection for his translations and frequently edited his work including the Book of Mormon and revelations of the Doctrine and Covenants throughout his life in an effort to conform them exactly with his doctrinal vision. Therefore the LDS vision of scripture is far more fluid and flexible than many others.
I hope this has been a useful stroll through the apparatus of the KJV so that readers will better understand the features included in the LDS Standard works and other KJV editions. If you have questions on specific verses use of italics, please drop me a note in the comments and I will do my best to answer them.