Many scholars have adopted the idea called the "Documentary Hypothesis". According to the Hebrews scholar Umberto Cassuto, the idea "postulates that the Pentateuch was composed by the amalgamation of sections and subsections derived from four independent source-documents, J, E, P, D.
The main reason many scholars have adopted this line of thinking is because of supposed discrepancies in the Pentateuch. The largest of these inconsistencies is the "divine names", or names used for God. The two names most commonly used are Yaweh and Elohim. Some say that because these two names are used at differing points, they must have originated from different authors, so there must have been different source documents that were used to compose the Pentateuch.
Let's leave aside the notion that there is NO MANUSCRIPT EVIDENCE AT ALL for any of these documents, and examine whether the use of Jehovah and Elohim would point to different authors or sources for the Pentateuch.
The first thing that is being presupposed by those supporting the documentary hypothesis is that Jehovah and Elohim mean the exact same thing. This is not the case. According to Cassuto, "Elohim was originally a common noun, an appellative, that was applied both to the One God of Israel and to the heathen gods." However, "the name Yaweh is a proper noun, the specific name of Israel's God, the God whom the Israelites acknowledged as the sovereign God of the universe and as the Divinity who chose them as His people."
Basically, Elohim is a general name for God the Creator, and Yaweh is a familiar name representing the relationship God specifically had with His chosen people.
Examples to follow...