FairMormon is a non-profit organization dedicated to providing well-documented answers to criticisms of LDS doctrine, belief, and practice.
O Livro de Mórmon/Evidências/Hebraísmos/Se e condicionais
Question: What do "if-and conditionals" tell us about the Book of Mormon translation?
If-and conditionals are not an English grammar form, and are not present in any texts which Joseph Smith knew
If-and conditionals are not an English grammar form, and are not present in any Bible (or other) texts which Joseph Smith knew or even reasonably could have known.  The presence of this grammatical structure has often been edited out in later editions, because it is poor English--but, it may provide evidence that the underlying plate text used Hebrew or a related structure.
This provides evidence that Joseph's claim to be translating an ancient record of Semitic origin was true.
The newsletter FARMS Insights noted in 1997, based on Royal Skousen's research: 
Recent research has yielded another interesting clue about the language of the Nephites and about the manner in which it was translated into English. By comparing the original manuscript of the Book of Mormon to the subsequent printed versions, Royal Skousen has found that the original English-language text of the Book of Mormon contained expressions that are uncharacteristic of English. One such expression is a Hebrew-like conditional clause.
In English, it is common to express a conditional idea in the following manner: "if you come, then I will come," with then being optional. In Hebrew this same idea is expressed in another manner: "if you come, and I will come." This structure makes perfect sense in Hebrew but is not found in English. When Joseph Smith translated 1 Nephi 17:50, he dictated "if he should command me that I should say unto this water be thou earth, and it shall be earth." This non-English construction was removed from this verse by Oliver Cowdery as he copied the original manuscript to produce the printer's manuscript. He deleted the word and, making the text read better in English. The sentence now reads: "if he should ..., it should be earth."
Thirteen other occurrences of this Hebraic conditional were printed in the first edition of the Book of Mormon and then later removed by Joseph Smith in his grammatical editing in preparation for the second edition of the Book of Mormon, published in 1837 in Kirtland, Ohio. One of these instances is the famous passage in Moroni 10:4, which originally read: "if ye shall ask with a sincere heart with real intent having faith in Christ and he will manifest the truth of it unto you by the power of the Holy Ghost" (1830 edition, p. 586). In the 1837 and all subsequent editions, the ands in conditional phrases like this one have been dropped to express the idea properly in English.
This use of and is not due to scribal error. Strong evidence of this is found in Hel. 12:13-21, where the if-and expression occurred seven times in the original English translation:
- 13 yea and if he sayeth unto the earth move and it is moved
- 14 yea if he say unto the earth thou shalt go back that it lengthen out the day for many hours and it is done[...]
- 16 and behold also if he sayeth unto the waters of the great deep be thou dried up and it is done
- 17 behold if he sayeth unto this mountain be thou raised up and come over and fall upon that city that it be buried up and behold it is done[...]
- 19 and if the Lord shall say be thou accursed that no man shall find thee from this time hence forth and forever and behold no man getteth it henceforth and forever
- 20 and behold if the Lord shall say unto a man because of thine iniquities thou shalt be accursed forever and it shall be done
- 21 and if the Lord shall say because of thine iniquities thou shalt be cut off from my presence and he will cause that it shall be so
This structure is perfectly acceptable in Hebrew, but these verses were changed in 1837 to make the book read more smoothly and convey the proper meaning in English.
These observations support the idea that Joseph Smith's translation was a literal one and not simply a reflection of either his own dialect or the style of early modern English found in the King James Version of the Bible. They also support the idea that the language from which the book was translated into English was Hebrew or Hebrew-like.
Examples of if-and conditionals in the Book of Mormon text
- See remarks near footnote 58 in Daniel C. Peterson, "Mormonism as a Restoration," FARMS Review 18/1 (2006): 390–417. off-site PDF link wiki
- Royal Skousen [researcher], "Hebraic Elements in the Language of the Book of Mormon," in Insights 17/12 (December 1997). off-site