Does biblical narrative ever conflict with biblical law? If so, which one predominates?

According to Deuteronomy 21:17 firstborn sons are given a double share of the inheritance. Thus, if a man had two sons, the firstborn received two thirds of the inheritance; if a man had three sons, his estate was divided into fourths with the firstborn receiving two-fourths or one half; if a man had four sons, his estate was divided into fifths with the firstborn receiving two-fifths; etc.

Unmarried daughters were supported by their father or brothers and they received an inheritance only if their father had no sons. Numbers 27 tells of Zelophehad’s daughters who appeal to Moses for their father’s inheritance. Moses, after speaking with God, gives them their inheritance, but in Numbers 36 Moses, to prevent tribal warfare, restricts the daughters (and thereafter any daughters in similar circumstances) to receive an inheritance only if they marry within their tribe. In Job we read that he gave his daughters an inheritance along with their brothers (Job 42:15); a clear deviation from biblical law.

Therefore, because firstborn sons enjoyed, by biblical law, enormous advantages with respect to power and inheritance, we might expect to read in the biblical narratives that most, if not all, of the male heroes were firstborn sons. But quite the opposite is the case and there are few things more striking that the biblical narrative’s preference for younger sons.

Of Abraham’s two sons, Ishmael is thirteen years older than Isaac, but there is no question that Abraham’s monotheistic mission will be carried on through the younger Isaac. Isaac has twin sons, with Esau being firstborn by several minutes ahead of Jacob; yet it is Jacob who is deemed to carry on the family mission.

Jacob has 12 sons. The oldest son Reuben outrages Jacob by sleeping with one of Jacob’s wives (Genesis 49:4) whereupon Jacob removes the right of his firstborn to inherit the estate and bestows it upon Joseph, his 11th son; and because he adopted Joseph’s two sons (Genesis 48:5), Jacob in effect gives Joseph a double share of the inheritance.

Aaron had many commendable traits, but the outstanding figure in the early biblical narratives is his younger brother Moses. Israel’s greatest king, David, is the youngest of eight sons. David too has many sons, but all we know about his firstborn son, Amnon, was that he was a rapist. David entrusts the kingship of Israel to the much younger and wiser son, Solomon.

One would expect, by the law of averages that a few first born sons should have been some of the great figures in the Bible, but they aren’t. Can the preeminence of younger sons be only a coincidence or are the biblical narratives citing a protest against a world in which firstborn sons were given preeminence for NO other reason than their birth order? Such seems to be the case. The biblical narratives seem to be teaching us that sons and daughters are to be judged according to their behaviors and not on the chronological order in which they are born.

Thus, in answer to the question, in this regard biblical narrative predominates over biblical law.