A second theory of kashrut is of the sort propounded by the nineteenth-century German rabbinic leader Samson Raphael Hirsch, who attempted to refashion the medical approach into a philosophical form. Hirsch argues that while man is both body and soul, “the body of man should be the serv­ant of his spirit.” This, he continues, can be accomplished only if the body“ is not too active in a carnal direction, if it is passive and indifferent to its own desires, and if it is submissive to the demands of the soul.” Further­more, the physical structure of man is influenced by “the kind of food he consumes,” and therefore vegetables are the most preferable food, as they are the most passive substance; thus we find that “all vegetables are permitted for food, without discrimination.” Next in order of desirability are those animals that are herbivorous and therefore nearer to the vegetable world. The Tora therefore permits animals that are herbivores and ruminants, and “spend a great deal of time in the absorption of food, which may be termed the vegetative activity of animals.” Similarly, Hirsch continues, the Tora forbade all fowl that are not passive in nature, such as birds of prey, as well as “lively artistic birds” such as songbirds or those that indicate artistry in building a nest. Finally, creepers and fliers are forbidden because ingestion of insects is dulling to the intellect.¹⁷

There are several problems with Hirsch’s theory. For starters, are all the permitted animals indeed more passive than the forbidden ones? Is the deer, for instance, truly more passive than the rabbit? One kosher animal whose flesh has become quite popular among American Jewry is the bison, expressly permitted in Deuteronomy. Yet can one really raise such an animal on a farm more easily than one raises a horse or pig? And what of the giraffe, a permitted animal that seems to lack the passivity of the decidedly non-kosher housecat? Similarly, Hirsch’s reflections on permitted fowl reflect his exposure to a rather limited range of cuisine; in fact, the list of kosher birds includes many that are less passive and more “artistic,” such as the pheasant, partridge, quail, guinea fowl, and sparrow. Furthermore, Hirsch himself ad­mits that when the Tora permits the ingestion of locusts despite its prohibi­tion of most other insects, “the explanation for this is not clear.” In the end, Hirsch’s writings on kashrut are interesting, but the reader may be left with more questions than answers.

A more modern explanation for kashrut is put forward by a number of modern authors. First suggested by the anthropologist Mary Douglas, the approach assumes that “in general the underlying principle of cleanness in animals is that they shall conform fully to their class. Those species are un­clean which are imperfect members of their class, or whose class itself com­pounds the general scheme of the world.”¹⁸ In what follows I will focus on one very interesting version of this approach, articulated by the philosopher Leon Kass, which, despite my disagreements, is nonetheless enormously helpful in formulating an explanation of the biblical dietary laws.

Kass begins by noting that at the outset of Genesis, God forbids the eating of meat, insisting that all creatures be vegetarians:

And God said: “Behold I have provided you with all seed-bearing plants which are on the face of all the earth, and every tree which has seed-bearing fruit; to you I have given it as food. And to every living being of the earth and to everything that creepeth upon the earth which has a living soul in it, I have given every green herb as food.” And it was so.¹⁹

God stresses the sanctity of creation and the value of all life by pro­hibiting man from eating any other living creature, and insisting that all creatures—from man to the lion to the eagle—eat nothing but vegetation. Keeping to this diet, Kass writes, “Would disturb almost not at all the order of creation”: ²⁰

Eating seeds and fruits does not harm the parent plants; eating fruit and discarding the seeds does not even interfere with the next generation. And the green herbs to be eaten by the animals are constantly produced by the earth, almost as a head produces hair.... The disruptions caused by meet­ing necessity through eating would, in the idealized case, be negligible.²¹

At the same time, Kass notes, it is quite clear from the text that man, and beasts, are potentially carnivorous; the very fact that they need instruc­tion in the art of eating indicates that “left to their own devices, their ap­petites might have extended to incorporate one another.”²² Man is thus ap­pointed as steward of creation even as it is made obvious that he can become its destroyer:

In this very subtle way, the text hints that the harmonious and ordered whole contains within it a principle—life or, if you will, appetite, and eventually omnivorousness and freedom—that threatens its preservation as an ordered whole. Once again the biblical account speaks truly: Life is destabilizing and threatens itself; man does so in spades. Despite (because of?) being created in the image of God, man alone among the creatures—except for heaven—is not said to be good.²³

After the flood, the Almighty acknowledges that “the imagination of man’s heart is evil from his youth”²⁴ and grudgingly allows mankind to eat meat. Nevertheless, God insists that in order to reinforce the sanctity of all life, any “flesh with its life, which is its blood, you shall not eat.” The Levitical dietary laws, Kass suggests, build on the original rules in Genesis. Israelites are allowed to eat meat, but must restrict themselves to those animals that, in their own respective diets, appearance, or means of locomotion respect the original boundaries of nature. Thus, the Jews “are not to incorporate animals that kill and incorporate other animals.”²⁵ Kass also sees the requirement of cud-chewing as a conscious distancing from carnivorousness:

Cud chewers are so far from eating other animals that they finally chew and swallow only the homogenized stuff they have already once swallowed and raised: When the pig, a notorious omnivore, is declared unclean, the Tora says it is because “he does not chew the chew,” using the cognate accusative construction (vehu gera lo yigar; Leviticus 11:7), presenting by implication, as it were, the ideal of the perfect fit of activity and object. The pig is a would-be ruminant gone bad: One should chew not life but chew—that is, that which is fit for chewing. The chew chewers are poles apart from that first accursed and most unclean animal, the belly-crawling serpent, which is in fact a moving digestive tract and which “voraciously” swallows its prey whole and live.²⁶

Furthermore, Israel is not “to incorporate or have contact with beings that do not honor in their motion the original separations of the world.”²⁷ For Kass, the laws of kashrut “build into daily life constant concrete and in­carnate reminders of the created order and its principles and of the dangers that life—and especially man—pose to its preservation. In these restrictions on deformation and destruction, there is celebration of Creation—and of its mysterious source.”²⁸

How, then, are these specific biblical criteria to be accounted for? Kass, like others before him, notes that the signs of unclean animals relate to their form, their means of motion, and whether they eat other animals or not. It is worth quoting his explanation of the Levitical conditions of kashrut in depth:

Ruled out are: (1) Creatures that have no proper or unambiguous place; for example, the amphibians. (2) Creatures that have no proper form, especially the watery ones, (a) by virtue of having indefinite form, with fluid shapes, lacking a firm boundary defined, say, by scales—that is, jellyfish or oysters;(b) by having deceptive form, like eels (fish that do not look like fish);or (c) by having incomplete form—like the incompletely cloven-footed animals. (3) Creatures that violate proper locomotion, such as those animals that live in the water but walk as on land (lobsters); those that live on land but swarm as in water (“all the swarmers that swarm on the earth”—in Genesis 1, the swarmers belonged in the waters); those insects that have wings for flying but that nevertheless go on all fours, that is, walk (the insect leapers, though they have legs, are treated as more akin to the true fliers, and are clean); also, those with too many legs (centipedes) or no legs at all (that go on their belly, for example, snakes, worms); and those that go on all fours, that is, on their paws (and thus use their hands as feet). (4) Creatures that violate the original dietary code, showing no respect for life—that is, the carnivorous ones. This consideration is especially evident (a) in the unclean birds, the identifiable ones being mainly birds of prey; and (b) in the requirement of chewing the cud, the mark of the ruminant animals that eat what God originally gave all animals to eat, the green herb of the earth.²⁹

Consider for a moment Kass’ fascinating explanation of kashrut: What aspects of the dietary laws are left unexplained? No mention is made of the requirement that kosher fish have scales as well as fins; as such, not only shellfish and clams but also clearly defined marine life, such as the shark, are prohibited. Perhaps one might suggest that those fish seemless fully formed, and more naked, than those that have both fins and scales. But how are we to explain the locust, permitted amidst all the abominated insects?