The Blogs: Fins and Scales, Hooves and Cud, Part II

What We Still Don’t Know About Kashrut

In Part I of Fins and Scales, Hooves and Cud, I explored a question that is easy to overlook.

If every fish with scales also has fins, why does the Torah mention fins at all?

If the pig is the only split-hoofed mammal that does not chew the cud, why not simply list it as the lone exception?

Both formulations would be logically equivalent—and significantly shorter.

Yet the Torah deliberately presents the full criteria.

My proposal was that the Torah’s wording makes sense when viewed through the lens of information theory. Rather than minimizing words, it maximizes the robustness of the message. Redundancy, in this view, is not a flaw but a feature that helps preserve meaning across generations.

That article asked:

Why did the Torah choose to express the rules this way?

This article turns to two different questions:

Why have dietary laws at all?

Why these specific biological criteria?

Why have dietary laws at all?

This question has been explored for centuries, and many thoughtful answers have been proposed.

The dietary laws may:

cultivate holiness and self-discipline;
distinguish the Jewish people from surrounding cultures;
reinforce obedience to God;
shape communal identity;
encourage ethical reflection.

Traditional Jewish thought also classifies many of these commandments as chukim—divine statutes whose ultimate purpose may not be fully accessible to human reason.

Whether one agrees with these explanations or not, they are well represented in both Jewish tradition and modern scholarship.

How Kashrut Shapes Jewish Identity

Among the existing explanations, I find one especially persuasive.

Many rabbis understand kashrut as a system that shapes Jewish identity.

Food is one of the most powerful markers of belonging. It influences daily life, family life, hospitality, festivals, and community. Dietary laws naturally create a shared culture while distinguishing one community from another.

This explanation makes a great deal of sense.

But it answers only the first question.

It explains why dietary laws exist.

It does not explain why the Torah chose these particular anatomical signs.

To see the difference, consider a thought experiment.

Imagine a world in which the Torah had declared that fish without scales were permitted while scaled fish were forbidden.

Or imagine that mammals without split hooves were kosher.

Would Jewish identity still have developed around those dietary distinctions?

Probably yes.

From the perspective of identity formation alone, many different dietary boundaries could have served the same social function.

That observation does not imply that the Torah’s actual criteria are arbitrary or lack deeper meaning. It simply means that identity, by itself, does not explain why these specific biological characteristics were selected.

Distinctive Food Rules Are Common

Judaism is not unique in using food to reinforce communal identity.

Similar patterns appear in Islam, Hinduism, Jainism, Sikhism, and among Russian Old Believers. These are only a few examples of communities where dietary practices help preserve identity, although the specific rules differ dramatically.

› Islam

Islam has halal dietary laws, including the prohibition of pork and prescribed methods of slaughter. Observant Muslims routinely ask whether meat is halal before eating it, and entire restaurants, grocery stores, and supply chains exist to meet these requirements. Like kashrut, halal transforms an ordinary act—sharing a meal—into an expression of religious identity.

› Hinduism

Many Hindus avoid beef as an expression of religious and cultural values. In many parts of India, refusing beef is not merely a personal dietary preference but a visible marker of religious identity. Families, festivals, and even restaurants often organize meals around this distinction, making food an everyday expression of belonging.

› Jainism

Jains extend their commitment to nonviolence so far that many avoid root vegetables, since harvesting them destroys the entire plant and disturbs organisms living in the soil. Some also avoid eating after sunset to reduce the chance of accidentally harming insects. To outsiders these rules may seem unusually strict, but within Jainism they form a coherent expression of ahimsa—the commitment to avoid harming living beings whenever possible.

› Sikhism

Sikh tradition takes a strikingly different approach. Observant Sikhs traditionally prohibit kutha meat—animals slaughtered according to ritual methods such as kosher or halal. In other words, where Jews and Muslims may seek ritually slaughtered meat, Sikhs avoid it. The same ritual act that makes meat acceptable in one tradition makes it forbidden in another. For Sikhs, an animal is not purified by a religious slaughter ceremony; turning the act of killing into a ritual is itself the problem. The dietary boundary still serves communal identity, but it is drawn in the opposite direction.

› Russian Old Believers

Russian Old Believers follow exceptionally strict dietary laws rooted in Old Testament (Tanakh) dietary restrictions and medieval Eastern Orthodox traditions. Products introduced to Russia after the seventeenth-century schism are viewed as heretical or corrupting. This includes a strict, lifelong ban on tea, coffee, sugar, tobacco, hard alcohol, and, in some sects, even potatoes. Old Believers are forbidden from eating or drinking from the same dish or cup as non-believers, heretics, or those considered “unclean.” They also eat separately from anyone who does not belong to their community.

These examples demonstrate that dietary restrictions can successfully create and preserve communal identity regardless of the specific foods or rules involved.

Why these specific biological criteria?

The previous sections addressed the first question:

Why have dietary laws at all?

Many explanations focus on the role of kashrut in shaping holiness, discipline, and communal identity.

But this leaves a different question unanswered:

Why these specific biological criteria?

Why fins and scales?

Why split hooves and chewing the cud?

Why not gills, feathers, number of toes, body temperature, or some other anatomical characteristic?

Despite centuries of interpretation and analysis, there is no generally accepted explanation—either in mainstream scholarship or in traditional Jewish thought—for why these particular biological signs were chosen.

Why Is It So Difficult to Answer?

Any proposed explanation must account for the entire system, not just a handful of examples.

Several categories of explanations have been proposed:

Health: The criteria may reflect concerns about safety or nutrition.
Ecology: The permitted and prohibited animals may reflect their ecological roles or habitats.
Biological classification: The criteria may correspond to natural categories of animals.
Symbolism: The physical characteristics may represent deeper spiritual ideas.

Each of these approaches contributes something valuable. However, each also faces significant challenges.

› Health

The health hypothesis is often suggested. Yet shrimp can be perfectly safe to eat, while kosher fish may carry parasites. The pattern is inconsistent.

› Ecology

Ecological explanations observe that many prohibited aquatic animals are scavengers or bottom dwellers. Yet many kosher fish are predators, while some prohibited species are not scavengers. Again, the pattern does not consistently hold.

› Biological Classification

Modern biological classification offers little help. The Torah was not written in the language of evolution or taxonomy, and the kosher criteria do not map neatly onto modern scientific classifications.

› Symbolism

Symbolic interpretations have inspired generations of commentators and often provide profound spiritual insights. Yet symbolic readings are inherently difficult to verify and rarely explain why one anatomical feature was chosen over another.

None of these approaches has produced a generally accepted explanation for why the Torah selected these exact biological markers.

Could There Be Another Explanation?

Possibly.

The criteria may reflect biological observations that were once familiar but are no longer fully understood.

They may encode a principle that remains undiscovered.

Or the choice of these particular signs may ultimately rest on theological reasons that cannot be inferred from biology, ecology, or history.

The honest answer is simple:

We do not know.

Do the Criteria Themselves Matter?

One further possibility is worth considering.

Perhaps the specific criteria are less important than the existence of clear and enduring criteria.

As we have seen, dietary restrictions can successfully create and preserve communal identity regardless of the particular foods or rules involved. Many religious communities have developed distinctive dietary practices, yet the specific prohibitions differ dramatically.

If so, the precise biological signs may not have been the essential point. What mattered was the existence of a stable, recognizable boundary.

Had the criteria rested on an obvious practical rationale—health, nutrition, or ecology—later generations might have argued that changing circumstances justified changing the law.

Criteria whose ultimate rationale remains elusive may be more resistant to reinterpretation. Their authority comes from the law itself, not from any particular scientific, cultural, or theological explanation attached to it.

If so, the absence of an obvious practical rationale may itself have helped preserve the continuity of kashrut across millennia.

Two Questions, Two Answers

This article began by separating two questions that are often treated as one.

Why have dietary laws at all?

Many explanations have been proposed. The explanation I find most compelling is that religious dietary laws, such as kashrut, serve to shape and preserve communal identity.

By regulating one of the most universal human activities—eating—they transform abstract beliefs into lived experience. Every meal becomes a reminder of belonging.

Why these specific biological criteria?

We still do not know.

Perhaps we have been asking the wrong question all along.

Instead of asking why the Torah chose these biological criteria, we might ask whether the particular criteria were ever the essential point.

A better question may be:

Did these particular criteria matter at all?

If the primary purpose was to create and preserve a stable communal boundary, then having clear, enduring criteria may have mattered far more than which criteria were chosen.

Perhaps the lack of an obvious rationale is itself part of the answer.

Or perhaps the oldest answer is still the wisest:

For so it is written.

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