Harvard's Shaye J.D.Cohen and Meir Soleveitchik have an exchange of letters in the Winter issue of Azure. Dr. Cohen claims with much justification that Dr. Soleveitchik misrepresents his (Cohen's) views on the origin of matralineal descent. For his part, Dr. Solevietchik answers with bluster, contending that matralineal descent is biblical. In proof of this, Dr. Soleveitchik cites an incident from the Book of Ezra.
In the incident a petitioner asks Ezra to expel all the "foreign women and their children," but does not ask for the same to be done to the "foreign" men and theirs. This, according to Dr. Soleveitchik, "proves" matralineal descent is biblical, meaning it is a law always in practice from the time of the Revelation of the Torah on Mount Sinai, and is based on Torah precepts, even though it is found nowhere in the Torah itself.
But this is a problematic citation for several reasons, not the least of which is the dating of Ezra, which by biblical chronology is of the last of the cannonical books. It describes events that took place after the return to Judea from the Babylonian exile. And it contains some unique history.
We learn from Ezra that many laws and practices thought to be biblical were unknown to the returnees, and Ezra had to "reinstitute" them. This is made even more problematic because Nehemia also appears to have been unaware of them, as well.
We also learn that Ezra had to "reinstitute" entire sections of the Torah which had become "lost" to the returnees. According to some Rishonim, Ezra also performed a lterary service, adding in every line that says, "And God spoke to Moses …," "God spoke to Moses …," "And Moses spoke …," etc. Others contend Ezra removed entire psalms from the "text" of the Torah and moved them to the Book of Psalms, no doubt for neatness of appearance. (For more on this, please see Marc Shapiro's book on the Rambam's thirteen principles of faith.)
This makes relying on anything in Ezra for the purpose of determining its "biblical" status problematic.
Perhaps realizing this, Dr. Soleveitchik notes that the petitioner refers to the Torah basis for his requested action, asking for the expulsion “in accordance with the Torah.” "The clear implication," says Dr. Soleveitchik, is that the petitioner "was suggesting not a supererogatory act, but rather a mandatory one whose biblical basis was already known to Ezra."
But as is well known, torah means teaching or law, and does not need to refer to the Five Books of Moses that bear its name. In fact, most usages of the word are just that – a reference to a teaching or a law taught by a specific sage or expounded by a particular public figure. The petitioner could just as well be referring to a teaching of Ezra, and that is perhaps the case here.
We find no mention of matralineal descent before Ezra, and we find it here only if we accept the notion that expelling foreign wives is linked to that and not to, for example, idol worship, as was the problem with King Solomon's foreign wives, Abraham's concubines, and their progeny. And, because both of these incidents are mentioned, one in the Torah itself and one in Neviim (Prophets), it is far more likely Ezra's petitioner was referring to them.
In attempting to prove his thesis that the "Jewish mother" is, despite her lack of protection in many legal areas and her inability to inherit her husband, a coequal or higher with Jewish fathers, Dr. Soleveitchik marshals support from the Talmud, written hundreds of years after the close of the biblical cannon:
"Yevamot states that a child born to a woman who converted mid-pregnancy is considered Jewish--that is, the child of a Jewish mother--despite the fact that the baby was conceived when his mother was a Gentile. This, as I noted, indicates 'the doctrine of matrilineal descent does not imply that the mother’s genetic contribution to the child at the moment of conception is more important than that of the father; it insists, rather, that the bond forged by childbearing and birth is stronger than any other familial attachment.'”
A far more plausible explanation is the status of the baby is determined by the status of the mother at the time of birth because we had (in those days) no surefire way to determine pregnancy in its earliest stages, and the idea of having a potential convert wait three or more months before converting is found nowhere in the biblical cannon. Further, a fetus is not considered to be a life in the fullest sense until birth. We see this from the biblical incident (Exodus 21:22) of two men fighting and accidentally injuring a pregnant woman who loses the baby. The man who caused the injury is not sent into exile like other accidental murderers; he pays a monetary fine, instead. One could easily argue this is the reason for the halakha mentioned in the Talmud.
So we see Dr. Soleveitchik discards scholarly diligence for the comforting world of rabbinic homily, and that is fine – so long as the distinction between the two is clear in both the minds of the author and his readers. With Dr. Soleveitchik, this is clearly not the case.