It appears, then, that in the post-Temple era both Jews and Christians utilized kashrut as a metaphor for God’s relationship with the Jewish people, and with the world. Peter, in abrogating kashrut, proclaimed the disappearance of all distinction based on descent, and the replacement of the nation Israel with the Church. As Christianity became the religion of the Roman Empire and spread to nations of all ancestries, the church believed Peter’s prediction to have proven true. The persecuted and exiled state of the Jewish people was, from the age of Augustine, taken as further confirmation that God’s favor was on the Christian faithful, and not on the physical descendants of Abraham. The Jews, meanwhile, their Temple in ruins, wandered the face of the earth. No longer were they separated from the rest of humanity by the borders of their holy land. In their suffering, Israel looked to Leviticus as a source of insight and consolation, knowing that just as God can choose a minority of the animals for the Jewish table, the Jews, despite being a persecuted and exiled minority, can remain the chosen of God. Exiled throughout the world, the Jewish people stubbornly clung to kashrut, insisting that its chosenness was unchanged. Not only by the words that came out of their mouths, but also by the food that entered them, Jews steadfastly proclaimed that the verse with which kashrut is explained remained eternally true: “And I have separated you from among the nations, to belong to me.”⁵³

Having studied much of the rabbinic perspective on animals and on kashrut, we are now able to appreciate what may be its most im­portant point of all, and what initially seems to be a bizarre hypothetical halachic scenario can now be understood as a profound statement about the nature of Jewish, and human, identity. In a Mishna that has provoked centuries of halachic debate and commentary, the rabbis present us with the following question: Suppose a cow gives birth to a horse, or a camel, or a pig. The supposition is not as strange as it may first seem. Let us imagine that, by birth defect or genetic mutation, a permitted animal produces off­spring that lacks one of the criteria of kashrut: Its hooves are not completely cloven or it lacks the ability to fully chew its cud. This hypothetical case is invaluable, for it allows us to examine whether the approaches quoted above are consistent with the rabbinic approach to kashrut. How would the several schools of thought that we have discussed regard this seeming non-kosher animal that was born to a kosher mother? For Nahmanides, the animal whose habits are akin to those forbidden ought to be similarly unhealthy and similarly shunned; Rabbi Hirsch, who argued that only the ruminant is similar enough to the vegetable world for Jews to eat, should insist that the animal that does not chew its cud is a philosophical symbol of the carnal and ought to be prohibited. For those modern writers who argue that the Bible abhors ambiguity and boundary-crossing, one ought to abominate this creature that, like the pig, is a ruminant gone bad: One that ought to act like a cow but does not. Neither the medieval medical interpretation, nor the Hirschian symbolic interpretation, nor the modern approach can justify allowing the eating of this animal solely based on its origin. Yet that is precisely what the Mishna does:

A cow that gave birth to a form of donkey… what is its status regarding eating? A pure animal that gave birth to one akin to an impure animal, it is permitted for eating, and an impure animal that gave birth to the form of a pure animal, it is prohibited for eating. For one that is born to a pure animal is pure, and one born to an impure animal is impure.⁵⁴

This principle is further codified by Maimonides himself in his Mishneh Tora.⁵⁵

What is the reasoning behind this rule? Later halachic literature would explain that criteria such as cloven hoofs and cud-chewing are not the cause of an animal’s kosher status, but merely signs by which man can, in general, differentiate between kosher and non-kosher animals. But once we distin­guish among species, then it is the essence of one’s transmitted heritage, and not one’s particular biological characteristics, that are of primary concern: As one of modern Jewry’s foremost talmudic scholars and bioethicists, J. David Bleich, put it, identity in Jewish law is determined first and fore­most not by how a subject is manifest, by rather by descent:

The matter of identification as a member of a species is best summed up in a pithy comment attributed to R. Chaim Soloveitchik. It is reported that R. Chaim explained a certain halachic concept by posing the following query: Why is a horse a horse? The answer is that a horse is a horse because its mother was of that species. For that reason the Mishna, Bechorot 5b, declares that the offspring of a kosher animal is kosher even if it has the appearance and physical attributes of a non-kosher animal and, conversely, the offspring of a non-kosher animal is non-kosher even if it has the ap­pearance and physical attributes of a kosher animal.⁵⁶

Thus, Bleich concludes, the halachic identity of an animal is ultimately “determined not by distinguishing characteristics, but by birth.”⁵⁷

An animal, then, that is born to a cow remains a cow, no matter how much its biological traits suggest otherwise. In analyzing whether an animal is kosher, it is its origin, not its attributes, that is critical. And though such a notion seems irreconcilable with the first three approaches to kashrut that we discussed, it is quite consistent with the approach we have suggested above. If kashrut is first and foremost an expression of chosenness and Jew­ish identity, then our manner of separation among the animals must express that one’s identity is dependent not only on how one acts, but also on the identity of one’s parents, ancestors, and nation. If, as we have been arguing, the rabbis took for granted that our manner of animal classification must mirror, and reinforce, the way we see ourselves, then kashrut implies an im­portant Jewish approach to Jewishness, and to the determination of human identity. After all, while a Jew is obligated in hundreds of commandments, his abandonment of Tora observance does nothing to affect his election. One is a Jew as long as one’s parents, or at least one’s mother, are Jewish.⁵⁸

It is crucial to stress that, despite the emphasis on one’s ancestry, the definition of Jewish distinctiveness is not a racial one. It is not a question of one’s genetic makeup at birth—for indeed, this is explicitly dismissed in the case of the animal that is born with traits that would seem to render it non-kosher. What is suggested, rather, is that there is something other than genetic reality that is transmitted from one’s parents: A kind of familial identity that makes us part of a specific collective, a nation, passed from one generation to the next. Membership in the chosen people is indeed something that one inherits and cannot repudiate regardless of his beliefs or actions: It is a covenantal obligation that is binding on the Jew from one generation to the next, and which inevitably links each Jew to future gen­erations. At the same time, however, it is a covenantal identity that is open for others to join: A non-Jew may convert to Judaism, entering into the covenant of this nation, and binding himself not merely to the same set of obligations, but to that essential, chosen community, an identity which he then passes on to his children. Jewish identity is thus inherently open to all, regardless of their biology. Yet it is also, indeed primarily, transmitted from parents to children—not as genetics, but as membership in a familial and national community.

In this respect, Judaism’s approach to identity differs drastically from both that of Christianity and the Enlightenment. For Christianity, one determines on one’s own whether one is a member of God’s covenant. Jewish theologian Michael Wyschogrod notes that it is for this reason that infant baptism has always been controversial, because “infant baptism seems to minimize the role of faith in Christian identity, as infants are not capable of faith commitment.”⁵⁹ Moreover, even those Christian denominations that practice infant baptism insist that “faith—even if fully realized years after the initial baptism—is the key to Christian identity.” One is on the whole autonomous in the determination of one’s identity, and one’s familial and national past is by and large irrelevant to this determination. The Chris­tian approach to identity, Wyschogrod suggests, is somewhat similar to the approach taken by the intellectuals of the Enlightenment:

The Enlightenment’s understanding of human identity, while not focused on faith in Jesus, shares with the Christian view the focus on human autonomy. Each rational human being chooses her own identity. Aspects of one’s identity not of one’s own choosing, such as sex, nationality, and age, are deemphasized. Instead, a person is depicted as largely responsible for her identity as a result of choices made. The major difference between the Christian and Enlightenment views is that in the Christian view, God’s grace plays a controlling role in the decisions human beings make. But if we can bracket the doctrine of grace, both the Christian and Enlighten­ment views depict a human being defined by the choices made and the life led. It is not the condition a person is born into that matters, but what the person makes of the condition in which she findsherself.⁶⁰