The author of the Pentateuch was virtually unanimously believed to be Moses until the 17th century. And even then, it was not until the 19th century that skepticism regarding Mosaic authorship caught on like wildfire so that the traditional view quickly became the minority view. Throughout the 18th century, serious debate regarding its authorship was waged by heavy hitters like Witte, Astruc, Eichorn, and Ilgen, who ultimately paved the way for the more substantive departures to come in the 19th century by positing the existence of a ‘Jawist’ and an Elohist, on the (rather anemic) basis of the variation throughout the Pentateuch of ‘divine names’.
Through the 19th century, a number of hypotheses were offered to replace the traditional view. Geddes suggested that the Pentateuch was the synthesized product of a multitude of fragments. Franz Delitsch posited a process whereby an initially straightforward sacred tradition was gradually supplemented until finally arriving at its canonical form, somewhere in the Exile period. Hupfield and Graf were pioneers of what has come to be called the ‘Documentary Hypothesis’, which taught that a definite and identifiable group of sources from varying Hebraic cultic traditions, were ultimately brought together into what we now know as the Pentateuch.
Wellhausen ingeniously took this notion and ran with it, presenting a ‘coherent’ reconstruction of ancient Hebrew history. He suggested that Israel’s religious history developed like all religious histories supposedly develop: They began, he said, very simple, with little cultic flair, disorganized and decentralized. By the time of the Deuteronomist, however, there was a push for a unified Temple worship, or, at least, the birth pangs thereof, and so the Pentateuchal sources were further redacted to reflect this (although, apparently not particularly well, since the ‘evidence’ for the previous, ‘decentralized’ religion of ancient Israel is supposedly still plainly visible in the text).
Finally, by the time the Priestly redactor came around, there was little left of the old Prophetic faith, with its emphasis on ethics and such. In its stead, we are told, there is an almost obsessive attention devoted to cultic practice – an elaborate sacrificial system, a colorfully defined Temple, and, most importantly, a ‘central sanctuary’.
Wellhausen’s reconstruction, or at least some variation thereof, has become more or less axiomatic in mainstream academia. Although he largely popularized the Documentary hypothesis, there are a few glaring methodological limitations, not least that its conclusions are largely unverifiable and, worse, unreplicatable (irreplicatable? Unreproducible? Irreproducible? Words are difficult.)
That is, of the manifold scholars who have followed in the footsteps of these skeptical trailblazers, few of them have arrived at terribly similar conclusions about the particulars of the formation and authorship of the Pentateuch. Generally, if a theory is good, it should easily replicated by those who go through the same process whereby it was reach.
But because the Documentary Hypothesis and its various cousins are almost entirely conjectural, they are impossible to work with. As a purely conjectural foundation, they back scholars who operate from them into a corner in which they are forced to content themselves with building entire careers on little more than glorified guesswork.
Nevertheless, the Pentateuch is complex. At some points, Moses is said to be meek, whereas he is elsewhere said to be mighty and bold. Contextually, these hardly need to be contradictory, but they do present a challenge. And, too, the Law codes, especially of Leviticus and Deuteronomy (and elsewhere) have their share of seemingly irreconcilable commands, but often this appears upon closer examination to be a case of non-overlapping casuistic scenarios. Even in cases in which apodictic commands appear to grate against one another, they do not, upon closer examination, need to be read as contestants in a zero-sum duel.
Moreover, reading through the Pentateuch, one is struck more by the remarkably theological consistency between even apparently disparate passages. The uniform witness of the Pentateuch is to God’s unique identity. He is the only Creator – the only one who can bara. He shares no common ground with the pagan deities, and has no difficulty dispatching them – and their subjects – when necessary. Whatever apparent diversity there is to be found in the beautifully complex books of Moses only underscores the broad theological unity thereof.
Thus, given the well-nigh unanimous testimony of the Church through the ages regarding Mosaic authorship of the Pentateuch, we ought to defer to those who have gone before us in regards to its Mosaic authorship and accept that the man himself was behind it – especially given the flimsiness of the skeptical objections by 17th-19th century elites.