Journal of the American Scientific Affiliation 26 (1974) 61-64. 

                    Copyright © 1974 by American Scientific Affiliation. Cited with permission.




                           The Levitical Dietary Laws

                                        in the Light

                                  of Modern Science


                                      Thomas D. S. Key and Robert M. Allen


                        Thomas D.S. Key                                 Robert M. Allen

                        Biology Dept                                         Science Dept

                        Oglethorpe University                            Babb Junior High School

                        Atlanta, Georgia 30319                          Forest Park, Georgia 30054


            Leviticus 11 presents dietary laws, specifying which animals are "clean"

( edible) and "unclean" (inedible). Nine major theories to account for these

dietary laws are described in this paper, giving arguments pro and con regard-

ing each. The theories discussed are the Obedience Testing, Arbitrary Divine

Command, Assertion of Divine Authority, Moral Discipline, Hygiene, Spiritual

Symbolism, Pagan Worship, Religious Badge, and Eclectic theories.

            The authors conclude that more evidence is needed, especially from

archaeology, to come to a definite conclusion regarding the validity of any of

these theories. They feel that if the original purpose of these dietary laws can

be determined, then perhaps we can make modern applications of lessons from them.




One of the most obvious characteristics of orthodox

conservative Jews as well as of Moslems and of the

Christian groups who emphasize the Old Testament is

the influence of the Levitical dietary laws on their

eating habits. Yet, when one questions those who

adhere to these dietary laws about the reasons for

them, he receives a variety of answers.

            Leviticus 11 describes "clean" animals (i.e., those

which may be eaten) as follows: any animals that

part the hoof, are cloven-footed, and that chew the

cud." Also, all aquatic animals that have fins and

scales, and winged insects that leap (i.e., locusts,

crickets, and grasshoppers) are "clean" or permitted

for food.

            "Unclean" animals (i.e., those that are forbidden

for food) were listed as follows: camel, rock badger,

hare, swine, aquatic animals lacking fins and scales,

eagle, ossifrages, osprey, kite, falcon, raven, ostrich,




nighthawk, sea gull, hawk, owl, cormorant, ibis, water

hen, pelican, vulture, stork, heron, crawling insects,

hoopoe, weasel, mouse, great lizard, gecko, land croco-

dile, bat, lizard, sand lizard, and chameleon.

            While the Bible nowhere states specifically why

the dietary laws were given, several theories have arisen

to account for them. Below are brief descriptions of

nine1 of these theories, along with some arguments for

and against their acceptance.


Obedience Testing Theory

            This view asserts that the choice of animals was

arbitrary, but that God's purpose was to evaluate the

spirituality of the faithful. The obedience testing theory

also considers the Tree of Knowledge of Good and

Evil (Genesis 2) to have been arbitrarily selected,

and that it was the act of disobedience that imparted

the knowledge of good and evil rather than any physio-

logical effect of the chemicals present in the fruit.

Pro: The Scriptures indicate in several places where

the faith of people was tested (Job, I Kings 19, Gene-

sis 2 and 3, etc.).

            Con: The choice of animals does not appear to be

arbitrary as the animals classified are consistent in

certain ways as discussed below.


Arbitrary Divine Command Theory

            It seems strange to some that most strict adherents

of the Levitical dietary laws accept this theory, though


62a                  T. D. S. KEY AND R. M. ALLEN


they may not refer to it by this name. According to

this theory, the animals were arbitrarily classified by

God as clean or unclean with no specific reason what-

ever. We are told that to raise questions about the

reasons or advantages of these laws is to evade the

issue. We are to accept these laws by blind faith.

The point is that God commanded, and we are to obey.

“God said it. I believe it. And that settles it. Period."

            Pro: If God had reasons for the laws, or if it were

important for us to know of them, they would have

been recorded. But such is not the case. The fact that

no reasons are given is evidence that they are unneces-

sary for us.

            Con: It seems inconsistent with a loving, just,

omniscient God to be arbitrary, or to command just

for the sake of commanding. The fact that the animals

hold certain traits in common (shown in some of the

following theories) would tend to rule out the concept

that they were haphazardly or arbitrarily chosen.


Assertion of Divine Authority Theory

            The purpose of these laws was to establish God's

authority, and to serve as a continual reminder of His

authority over and concern for His people, according

to this theory. These laws are beneficial in that they

tend to establish a habit of thinking frequently about

God and His place in our lives.

            Pro: The concept of God's establishing His author-

ity and reminding others of it is certainly consistent

with many Scripture passages, for example, the re-

quiring of phylacteries, and redeeming each first-born

donkey with a lamb (Exodus 13:13-14); the Sabbath

(Exodus 20:8-11); the rainbow (Genesis 9:11-17);

stars (Genesis 1:14); the mark on Cain (Genesis 4:15);

Miriam's leprosy (Numbers 12:10); circumcision

(Genesis 17:11); and labor pangs, toil and thorns

(Genesis 3:17-19). The fact that no reasons are given

means none are needed. Reasons would weaken His


            Con: The selection of animals would seem to in-

dicate that there was more to it than this (as indicated

in certain of the following theories). It would seem

arbitrary and superficial for God to assert His author-

ity in such an unproductive fashion. Would it not be

more profitable for God's kingdom and the spiritual

welfare of countless people if God required His people



to seek to win others to His ways? If God's purpose

for these laws is simply to assert His authority, why

would He not make useful laws, such as requiring the

faithful to be neighborly?


Moral Discipline Theory

            According to this concept, the laws were to teach

moral discipline, much as it was once believed that

mathematics and Latin should be taught to discipline

the intellect. For similar reasons some military acade-

mies have required certain patterns of eating (i.e.,

special ways of holding silverware, of sitting erect

while eating, etc.) in order to remind cadets constantly

of their discipline.

            Pro: The Bible is consistent with moral disciplinary

techniques. The fact that the price of a whore and of

a dog (Sodomite) were unclean tends to favor the

moral interpretation of these laws. In numerous pas-

sages the Hebrews were reminded that they "came up

out of the land of Egypt." (Deut. 23:4). These dietary

laws would serve as similar daily reminders of their

moral discipline. Nazarites were to remain unshaved

and to abstain from alcohol for disciplinary reasons

(Numbers 6:2-20). Paul beat his body into subjection

(I Cor. 9:27). "The rod" is to be used for discipline

in certain circumstances (Proverbs 10:13; 22:15; and,


            Con: As with the preceding theories, the particular

animals selected to be clean or unclean appear to have

enough in common to warrant other explanations than

this. To limit what foods may be eaten merely for

reasons of moral discipline, and to allow no exceptions,

could result in malnutrition, death, or forcing an im-

moral beaking of the laws in the event of famine,

poverty, or other problems.


Hygiene Theory

            The adherents of this theory point out that there

is close correlation between clean animals and those

that are less likely to transmit zoonoses (diseases

spread from animals to man), and between unclean

animals and those that are most likely to transmit

worms, bacteria, and other pathogens to man.

            Pro: Hogs are particularly likely to spread disease,

e.g., trichinosis and Ascaris. Buzzards can transmit

many of the diseases that kill the animals on which

62c                              T. D. S. KEY AND R. M. ALLEN


they feed. Rat meat could give those who eat it

trichinosis and other diseases.

On the other hand, while cattle can give us tuber-

culosis, tapeworms, undulant fever, for example, they

are much less likely to give us more serious diseases.

Essentially the same can be said for sheep.

Any fish that "looks like a fish" is considered clean,

while oysters, clams, and other sea creatures are un-

clean. It is noteworthy here that true fish as a rule are

less likely to be carriers of zoonoses than are other

aquatic animals.

Not only does the hygiene theory account for the

particular selection of clean and unclean animals, but

also accounts for the listing of other unhygienic things

as unclean. For example, human wastes were unclean!

(Deut. 23:12-14), as well as cooking utensils and other

solid objects which were contaminated by people with

running sores (Leviticus 13:47 and 14:34-55).

Paul wrote to Timothy that he should not drink

water, but should drink wine (I Timothy 5:23). Paul's

reason obviously favors the hygiene theory, as water

was often polluted by human wastes, carcasses and

other bacteria sources.

            Con: A much more sensible and practical regulation

would be to specify that all animals in sanitary environ-

ments are clean, while those that are raised in unsani-

tary environments are unclean. Or, better still, proper-

ly cooked meat is clean, while raw or rare meat is

unclean, regardless of the animal from which it comes.

If this were the regulation, not only could beef, mutton,

and true fishes be eaten without fear of zoonoses, but

the same would be true even of pork and other animals

listed as unclean. This theory also faces the difficulty

that unclean animals were let down from heaven to

Peter (Acts 10:9-29 and 11:5-12), and God responded

to Peter's refusal to eat with, "What God has cleansed,

you must not call unclean." The fact that menstruating

women and women who had just given birth were con-

sidered unclean (Leviticus 12), showed that the desig-

nation of unclean does not necessarily imply a poten-

tial source of contagion or infection. The fact that the

price of a whore or of a dog (or Sodomite) was un-



clean shows the same. Although there are numerous

poisonous plants, none is listed as unclean. And al-

though water could be polluted by carcasses, human

wastes, and other contaminants, nothing is discussed

regarding clean or unclean water. Even in those days

water was a main source of the spreading of disease.

Paul's advice to Timothy not to drink water was of

course written many centuries after the dietary laws

of Leviticus, and under the circumstances of Timothy

going on missionary journeys in which water could be


            Some object to the Hygiene Theory on the grounds

that little was then known about hygiene, while others

insist that these hygiene laws prove divine inspiration.

(See also Matthew 15:11).


Spiritual Symbolism Theory

            It is pointed out by those who favor this theory

that the clean animals have in common the fact that

they all symbolize spiritual virtues, while the unclean

animals symbolize spiritual vices.

            Pro: It should be emphasized that the Bible is an

Oriental book, and that Orientals have long been noted

for symbolic and figurative speech. The Bible uses

several symbols for Christ: e.g., lamb (John 1:35),

lion (Revelation 5:5), root (Revelation 5:5), and

grapevine (John 15: 1). The Holy Spirit is symbolized

by the dove (Luke 3), fire (Hebrews 12), and water

(Acts 11:16). God, Satan, Israel, the church, the re-

bellious wicked, the Gospel, sin, and other persons

and concepts are represented by still other symbols, and

many of the symbols were animals. Cattle and oxen

are clean animals because they represent honest hard

work and obedience to duty. Donkeys are unclean as

they symbolize stubbornness, spiritual stupidity, and

selfishness. Snakes are unclean because they depict

Satan and sin (Genesis 3:1-15). Hogs are unclean

because they are greedy and look down. The horse is

unclean as it symbolizes pride and human military


            Con: While the Spiritual Symbolism Theory is in-

triguing, it has some fatal inconsistencies. The lion is

unclean, yet it is used to represent Christ (Revelation

5:5) and the righteous (Proverbs 28:1). The pearl

represents the church (Matthew 13:46), yet is pro-

duced by unclean clams and oysters. The symbolism in

63b                              T. D. S. KEY AND R. M. ALLEN


the Bible is not intended to be consistent and clear-

cut as this theory would assume. Thus, while doves

illustrate the Holy Spirit (Luke 3: 22), they also illus-

trate wicked Ephraim (Hosea 7:11). The donkey is

an unclean animal, yet was chosen by Christ to ride

for His "triumphal entry" into Jerusalem (Matthew

21). The serpent was a symbol of Satan, but was also

used for salvation (Numbers 21:9). Grapes are clean,

but their juice was warned against when it is fer-

mented (Ephesians 5:8 and I Timothy 3:3), and was

forbidden to Nazarites under most circumstances

(Numbers 6:3-20). The eagle is unclean, yet is used

to symbolize God's power (Revelation 4:7). The lion

is used to symbolize Christ (Revelation 5:5), Satan

(I Peter 5:8), the righteous (Proverbs 28:1), and the

rebellious wicked (Joel 1:6).


Pagan Worship Theory

            It is noteworthy that the Hebrews spent centuries

living among neighbors who worshipped animal-like

gods. Part of the worship rites of these religions some-


While the Bible nowhere states spe-

cifically why the dietary laws were giv-

en, several theories have arisen to ac-

count for them. Given here are brief

descriptions of nine of these theories,

with arguments for and against their



times included the eating of these animals. Thus, the

sacred animals of these pagan religions were unclean,

while animals not sacred to these religions were clean.

            Pro: The eagle was sacred to the Egyptians. The

snake, hawk, hog, goat, and horse were sacred to other

neighboring religions. Sheep, camels, true fish, and

most plants were not sacred to the nations and tribes

around the Hebrews, and hence were clean. The

faithful were to avoid all appearance of evil (I Thes-

salonians 5:22). They were forbidden to eat food

sacrificed to idols (Revelation 2:14, 20). It is inter-

esting that even today Arabs consider eating with

someone to be a close form of fellowship.

            Con: Several plants were sacred to the pagan re-

ligions, but were not unclean (II Kings 23: 4). Cattle

were sacred to several groups (II Kings 17:16), yet



were clean. There have long been fish gods and sea

gods, yet true fish were clean. In fact, fish deities are

more common than clam, oyster, or shrimp deities, yet

the fish were clean while the latter were not.


Religious Badge or Mark Theory

            Many peoples have done or worn certain things to

distinguish themselves from others. The uniforms of

certain occupations are partly for this purpose, as are

some greetings, gestures, hairdos, and customs. The

Jews were God's earthly chosen people (Deuteronomy

7:6), chosen to witness for Him.

            Pro: The Jews were required to do several things

as religious marks or badges to make them stand apart

as witnesses for God: circumcise their boy babies

(Genesis 17:10-27), rest on the Sabbath (Exodus

20:8-11), wear phylacteries on their foreheads (Exo-

dus 13:16) and the like. The dietary laws were a log-

ical extension of these religious badges. The Bible

describes several other marks or badges of spiritual

significance. Paul was blinded on the road to Damascus

to get Paul's attention and to show God's mark of

approval of Christ (Acts 9:3-9). Zechariah was struck

speechless for several days as a mark of God's relation-

ship to Christ's birth (Luke 1:18-23). Moses' sister,

Miriam, was marked with a whitish skin disease to

show God's disapproval of her objecting to Moses'

dark skinned African wife (Numbers 12:1-15). God

put a mark on Cain's forehead as a warning that no

one was to seek revenge against him (Genesis 4:13-

15). The Nazarites wore long hair and beards and ate

a strict diet (Numbers 6:1-21).

            Con: The selection of clean and unclean animals

does not appear to be haphazard, but to fit certain

patterns (as discussed in some of the foregoing

theories). To prohibit certain wholesome foods merely

as religious badges could result in malnutrition or death

during famines. It could severely handicap the poor or

physically disabled. It could result in financial exploi-

64a                  T. D. S. KEY AND R. M. ALLEN


tation and monopolies of the few clean species. It

could result in upsetting the balance of nature due

to extermination of some species and the ignoring of

others. A more practical badge would appear to be

some kind of ritual associated with food preparation

or eating.


Eclectic Theory

            Some Bible students prefer to combine parts of two

or more of the above theories to account for the reasons

behind the dietary laws. Actually, there are many vari-

ations of the eclectic theory. They obviously differ on

which of the above explanations are regarded as valid,

and to what extent the accepted explanations are con-

sidered to account for each animal.

            Pro: The fact that the Bible does not indicate any

one reason might be due to the fact that several ex-

planations are necessary. The fact that several of the

preceding theories appear to be partially valid, yet

no one of them is capable of accounting for each an-

imal indicates that some eclectic explanation is neces-

sarily the correct one.

            Con: It is difficult to evaluate the eclectic theory

as its variations are so numerous. Yet, the con argu-

ments for each of the preceding theories are sufficient

to show that none is valid as understood at present. If

all the links in a chain are weak, simply adding more

links will not make it stronger. Adding more straw to a

straw house does not make it more fireproof. Likewise,

simply adding useless theories together does not make

a valid explanation.



            In the light of the above the authors conclude that

present evidence is not sufficient to warrant total ac-

ceptance of any one of the nine theories. More evidence

is needed, especially from possible future archaeological

discoveries. In the meantime, it would appear that, in

the light of the different kinds of dietary and other

"hygiene" laws given, that some eclectic interpretation

is probably correct.

            It should be noted that many Christians feel that

it is no longer necessary to obey the Levitical dietary

laws as the Old Testament Law was our "schoolmaster"

to bring us to Christ (Galatians 3:24-25). Their in-

terest in them is primarily historical. Yet if we are



able to determine the original purpose of the laws,

perhaps we can make modern applications of lessons

from them. For this reason it is recommended that

further study be made on this subject.




l A tenth important theory was inadvertently omitted: the

            Social Mores Theory. It argues that all societies have

            certain customs and taboos, and that the dietary laws

            are no more than this.

American Public Health Association, The. The Control of Com-

            municable Diseases in Man. U.S. Public Health Service, 1950.

Cable, Raymond M. An Illustrated Laboratory Manual of Para-

            sitology. Minneapolis: Burgess Publishing Co., 1958.

Chandler, Asa C. Introduction to Parasitology, 9th Ed., New

            York: John Wiley &; Sons, Inc., 1949.

Lapage, Geoffrey. Animals Parasitic in Man. Glasgow: Robert

            MacLehose and Co., Ltd., 1957.

Rosebury, Theodor. Life on Man. New York: The Viking Press,


Yearbook of Agriculture, The Animal Diseases. Washington:

            The United States Department of Agriculture, 1956.

Yearbook of Agriculture, The Food. Washington: The United

            States Department of Agriculture, 1959.



This material is cited with gracious permission from:

            The American Scientific Affliation

            P. O. Box 668

            Ipswich, MA  01938


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