Oh wow, you didn't say this was going to turn into a broader discussion of textual criticism! I am very much interested in such discussions but this topic is larger than I have the time to discuss right now.
My own opinion having done some research on the matter is that the Masoretic and DSS Hebrew texts preserve authentic tradition of the original Hebrew text (with occasional corrections from the LXX) though obviously they diverge from one another and must be 'criticized' for redaction, scribal errors, and additions or subtractions from the text. The DSS actually agree in places with the Septuagint against the Masoretic text (which was a later text - but still remarkably does not differ enourmously from the DSS - which is why we celebrate that the DSS confirmed that God preserved his Word remarkably throughout generations). In some other cases using comparative methods to the LXX and even some early Latin manuscripts the Masoretic Text (or the LXX itself) is to be prefered to the DSS. However it is my opinion that the LXX is far from perfect and scholars have long pointed out that some books in the LXX are very literal translations while there are more than a handful which are
very loose in their translation. I could perhaps get you a list of exactly which books are loosely or even "poorly" translated from the Hebrew. When we see a divergence of the LXX from the Masoretic text for example it often can be attributed to a Greek mistranslation, misinterpretation, or paraphrase of the Hebrew and not the other way around. Yes the LXX is valuable, but I do not trust it as a primary text and always prefer the Hebrew if it is available.
I personally trust the Hebrew text (taking into consideration the DSS) more than the Septuagint alone (for example in the LXX Jeremiah is 1/8 shorter than in the Masoretic text) although we can see more ancient forms of the text preserved in the LXX than in the Masoretic text on occasion, which however can only be judged largely by comparison to the DSS to see if
they too have that older reading or manuscript tradition.
Wikipedia provides a convenient illustration of this, "
Different Hebrew sources exist for the MT and the LXX.
Evidence of this can be found throughout the Old Testament. Most obvious are major differences in Jeremiah and Job, where the LXX is much shorter and chapters appear in different order than in the MT, and Esther where almost one third of the verses in the LXX text have no parallel in the MT". (
source)
However one example of a correction to the Masoretic text for a longer (more ancient) reading is the addition of 4 "missing" verses at the beginning of
1 Samuel 11 which give more historical details of the Ammonites opressing Israel (and why it provoked Saul to act) and the DSS have that longer account - the 4 extra verses (I'm not sure if the LXX does though or not). However once it was realized that this may have been an authentic and older manuscript tradition it was also noted that
Josephus had already recorded those exact same events in their expanded/elongated form when recounting the story of Samuel in his
Antiquities, thus those missing verses were preserved in Josephus even before the DSS were found.
That then brings me to a final point that other "smaller" or alternate sources can be used to check ancient manuscript and textual traditions including (for the Old Testament): The Samaritan Pentatuech, the Jewish Targums, Josephus, the two silver scrolls from Ketef Hinnom (having fragments of Deuteronomy), and some other Hebrew/Aramaic manuscripts found in Egypt; and (for the New Testament) Early Old Latin, Sryriac, Aramaic, and Coptic manuscripts and the writings of the Church Fathers. Enlisting help from works of other people such as Josephus and the Church Fathers is often overlooked, but they make many quotations of Scripture in their works that are of some value in piecing together the originals.
But I dare not say much more without launching this thread into pages of discussion. :D Perhaps another thread is suited for this? I'm sure we already have some threads on textual criticism and manuscript traditions somewhere.
God Bless,
~Josh