Why keep kosher?[1]


The eleventh chapter of Leviticus specifies some, but not all, of the basic kosher laws, which were later explained and elaborated upon by the rabbis in what they called the “Oral Law.” The physical characteristics of animals – split hoofs and bringing up its cud – classify those that can be eaten. Similarly, fish that possess fins and scales can be consumed. The eatable birds and teeming creatures are identified by name.



1. How do the above-mentioned three commands blend with the other Torah food and non-food regulations?

2. What are some reasons for these laws?

3. Does the Torah reveal reasons for the commands?


Torah food laws

An understanding of the rationale underlying the kosher rules requires people to recognize at least three things:

1. The commands prohibiting certain animals, birds, and fish are only a small part of many biblical food prohibitions. Each ban has its own reason. Among others, Jews are barred by biblical and rabbinic enactments from eating blood, a kid seethed in its mother’s milk, mixed meat and milk foods, the sciatic nerve, certain animal fats, animals that died a natural death, unsalted animals, animals that were not slaughtered according to the prescribed procedure, mixed species, consuming terumah and maser by an Israelite, eating the edge of one’s field and the growth of trees in its early years.

2. In addition to realizing that the food laws are quite extensive, one should also know that the practice of calling only certain food restrictions “unkosher” is not biblical. The word “kosher” does not appear in the Pentateuch. It is found only three times in post-Pentateuch scriptural books – Esther 8:5 and Ecclesiastes 10:10 and 11:6 – and none of these three sources use the term “kosher” to refer to food laws. The name “kosher” or “kashrut,” as it is used today, means “fit” or “proper.” There is no indication as to what “fit” applies. It may refer to fitness of the mind, body, life, holiness, or to something else, such as the Tabernacle worship. The Bible gives no reason for its commands about animals, birds, and fish.

3. It should also be understood that Leviticus 11, which mentions the ban on eating certain animals, birds, and fish, is part of a larger priestly code of purity, for the majority of the chapter prohibits contamination and contact with the dead bodies of the prohibited animals. The dietary laws are repeated in Deuteronomy 14, but Deuteronomy does not recap the laws of contamination.

Leviticus 11 ends the dietary and contamination laws by stating that avoidance of contamination is a prerequisite to becoming a holy people: “For I am the Lord who brought you up from the land of Egypt to be your God – you must be holy, for I am holy.” Exodus 22:30 also mentions holiness as a reason for avoiding contaminated items.

In short, what we call today the laws of “kashrut” is only a small part of the Torah food prohibitions, the Bible itself never separated one segment of the food laws (the rules of “kashrut”) from the other prohibitions, and even the laws of permitted animals, birds, and fish are mixed with rules concerning contaminated foods/animals.

Ignoring the other food rules, why were certain animals, birds, and fish prohibited?



The Spanish mystic Nachmanides (1195–1270) focused on the fact that these dietary decrees are joined to the laws of purity in the biblical section concerning the Tabernacle, and he equates the two. In the beginning of his comment on chapter 11, he wrote that the purpose of both laws is to protect the sanctity of the Tabernacle. He states that both sets of commands apply to the Israelites and the priests, “but the subject matter of the section affects the priests more than the Israelites because they need to guard themselves from touching impure objects, since they must enter the Sanctuary and they eat hallowed foods” which are prohibited to be eaten when the priests are impure. The Israelites are “also warned against eating impure foods, so that they would not defile the Tabernacle and its hallowed objects.”

(Curiously, in his comment on 11:9, he explains that fish without fins and scales are banned for health reasons, because they swim in the deepest cold and muddy waters. He does not assign a health reason for the prohibited animals and birds, and the health rationale seems to conflict with the idea of sanctity that he mentioned earlier.)


Moses Isserles

The Polish expert on Halakhah, Moses Isserles, better known as “Rema,” (1525 or 1530–1572) concentrated on the chapter’s final statement about holiness, and insisted that the holiness rationale, mentioned for contaminated substances, also applies to the dietary injunctions. In his comment on Shulchan Aruch, Yoreh Deah 81:7, he contended that consuming non-kosher food deadens one’s spiritual capacity to the extent that one does not even realize the loss. He advises that even though most laws do not apply to young children, one must protect small children from this spiritual loss and not allow them to eat non-kosher foods.



The ancient apocryphal book Tobit – of unknown date, but perhaps as early as 550 BCE – which was not included in the Bible, also apparently concentrated its attention on the holiness aspect that is mentioned in the chapter. Since the basic meaning of kodesh, “holiness,” intends “separation,” the book states that the food laws are designed to keep Jews apart from non-Jews.


Letter of Aristeas, Philo, Genesis Rabbah and Leviticus Rabbah

Holiness can also denote a proper life. Thus it is no surprise that the first century BCE volume Letter of Aristeas suggests that the food laws teach Jews about justice and other moral lessons. Similarly, the philosopher Philo (20 BCE–50 CE) wrote that creatures with evil instincts are forbidden because their instincts can be transmitted to humans who eat them. The Midrashim Genesis Rabbah 44:1 and Leviticus Rabbah 13:3 (around the fourth century CE) are similar when they state that the laws refine people.



The Bible and Talmud commentator Rashi (1040–1105) relied on Midrash Tanchuma and drew his reason for the dietary laws from a single word. He insisted that non-kosher foods kill people. This, he states, is evident by the Torah’s use of the introductory words “these are the living things.” The phrase, according to him, does not refer to the living things that may be eaten, but to those animal foods that sustain life; while unkosher animal foods do the opposite – kill. Neither the Midrash nor Rashi explain what kind of life they mean. Are they talking about health, spiritual life, intelligence, life after death, or something else?



Some mystics seem to have answered the question we asked about the Midrash and Rashi. Joseph Gikatilla (end of the 10th century), Menachem Recanati (about the beginning of the 14th century) and Isaac Arama (c. 1460–1545), for example, insisted that improper food can defile the body, pollute the soul, and confuse the intellect.



The Nagid (the spiritual and political Jewish Egyptian leader) Maimonides (1138–1204) presents his reasons for the scriptural commandments in chapters 25–54, the final chapters of his Guide of the Perplexed. His general explanations of the biblical commands are three things: instilling proper ideas, improving society and improving the individual. He writes in chapter 31 that the purpose of “every one of the 613 precepts serves to inculcate some truth, to remove some erroneous opinion, to establish proper relations in society, to diminish evil, to train in good manners, or to warn about bad habits. All this depends on three things: opinions, morals [individual behavior], and social conduct” (translation by M. Friedlander).

Maimonides saw a health advantage to the individual in the laws of kashrut, “the food that is forbidden [is forbidden] by the law [because it] is unwholesome.”


Ibn Ezra and the Sifra

The Spanish Jewish Bible commentator Abraham ibn Ezra (1089–1164) and the Midrash Sifra (fourth century C.E.) of the Land of Israel focus on the fact that the Bible offers no reason for the food commandments, and emphasize that they are divine decrees. Ibn Ezra simply states that we cannot know the reason. Sifra warns the Jew, “Do not say, ‘I do not like pig’s flesh.’ Instead, say, ‘I like it but I must abstain because the Torah forbids it.’”



The biblical food laws are quite extensive and include many prohibitions beyond the commonly recognized rules banning the eating of certain animals, bird, and fish. The term “kosher” is not biblical, and was selected in post biblical times to include some of these forbidden food rules. Each of the banned foods has its own rationale.

The prohibitions against eating certain animals, birds, and fish are detailed in Leviticus 11 and Deuteronomy 14, where they are combined with bans against certain contaminated animals/foods, such as the carcasses of prohibited animals. The Bible gives no reason for the food restrictions in these chapters.

The ancient sources and Bible commentators offered a host of widely disparate grounds for these commands. The rationales varied according to where the analyst focused his attention. Some looked at the juxtaposition of the food laws with those concerning contamination. Others took the purpose of the contamination, not the consumption directives – holiness – and applied it the food decree.

Several drew their interpretation from their understanding of a single word taken out of context. Another group, like Maimonides, relied on their general view of the aim of the divine commands – in Maimonides’s case; they were promulgated for health or ethical reasons. Still others, such as ibn Ezra and Midrash Sifra, insist that Jews cannot know the reason for the kosher laws and Jews must observe kashrut because God told them to do so, and for no other reason.

In short, the rationales offered for the biblical dietary regulations illustrate the many and divergent concerns of Jewish commentators.

[1] This is a version of a chapter that I wrote for my “A Rational Approach to Judaism and Torah Commentary,” published by Urim Publications.