If a person believes that the written Torah contains thematic truths as a result of foreknowledge and intent by G-d, but that words of the Torah itself have been influenced by the affairs of mankind (in a manner similar to that put forward in the "documentary hypothesis"), could such a person still be said to have beliefs within Karaite Judaism?
Your title is
Does Karaite Judaism necessarily reject the Documentary Hypothesis? Yes it does necessarily reject the DH
The reason for this is that your question as asked would be rejected by both the Karaites and those who follow the Documantary Hypothesis.
The body of your question has the phrase
(in a manner similar to that put forward in the "documentary hypothesis")
As I explain, the basic Karaite belief is in the divinity of the Torah as given to Moshe and the basic belief of the DH is that the Torah was written by human authors and editors starting in the time of Solomon and ending in the time of Ezra, with no divine input.
The Karaites believe that the Torah was given to Moshe at Har Sinai and has not been changed. While they accept Neviim and Kesuvim, those sections are not a change to the Torah. The Karaites do not accept the mishnah or talmud because they say that they are a change to the Torah.
Being a Karaite Jew means we only recognize the Miqra or Tanakh as divinely given.
Karaism is the original form of Judaism as prescribed by God in the Torah. Karaite Judaism rejects later additions to the Tanach (Jewish Bible) such as the Rabbinic Oral Law and places the ultimate responsibility of interpreting the Bible on each individual. Karaism does not reject Biblical interpretation but rather holds every interpretation up to the same objective scrutiny regardless of its source.
The Karaite Declaration of Faith, called Tuv Ta'am (after the first two words in Hebrew) has been recited in the Karaite Synagogue on High Holidays since at least the 13th Century, with an abridged version being recited twice daily. The Karaite "Declaration of Faith" consists of a series of statements read aloud by the Hazan (cantor). The congregation responds to each statement by emphatically shouting Emet! meaning "Truth!".
This includes the bullet point that
The Karaite "Declaration of Faith" includes the main principles and practices which give Karaism its unique character including:
- The truth of the Torah given to Moses.
This means that the part of the statement that says
but that words of the Torah itself have been influenced by the affairs of mankind (in a manner similar to that put forward in the "documentary hypothesis") would not be true, since the Torah was not changed since Moses received it.
On the other hand, the Documentary Hypothesis would not accept the part of the statement
the written Torah contains thematic truths as a result of foreknowledge and intent by G-d because they would not accept that Hashem gave the written Torah to Moses in any form.
As discussed in articles like The History and Salient Points of the Documentary Hypothesis, this myth pretends that every section of the Torah can be attached to a human author (or authors) with a mythical (human) editor who could not be bothered to insist on consistency. Additionally, this hypothesis insists that different sections were written and edited starting from the beginning of the first temple, to after the time of Ezra.
J, the oldest, begins at Genesis 2:4b and includes large portions of Genesis as well as portions of Exodus and Numbers and a few short texts in Deuteronomy. It may be dated to the early monarchy (Solomonic?) period.
P was produced last, in the exilic period. It begins at Genesis 1:1 and includes large portions of Genesis, Exodus, and Numbers and all of Leviticus. In Genesis, P refers to God as Elohim since, like E, it assumes that the divine name Yahweh was first revealed at the exodus (Ex 6:3, a P text). It is dominated by genealogies, priestly regulations, and a highly stylized manner of narration. P was soon redacted into JED by RP. The Pentateuch was thus formed.
The article cited actually goes into great detail as to the presuppositions of the Documentary Hypothesis and why it can be seen that it does not believe in the divine origin of the Torah. However, that would be too long for this question and would be the subject of a post to a different question.