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What is the source of the Seven Noahide Laws?

Cheshvan 5783 | October 2022

The first Rashi on the Torah questions why the Torah begins with Bereishit when the commandments only begin in Parshat Bo. Yet there are explicit commandments as early as Parshat Bereishit! There are “individual commandments” like the prohibition against eating from the Tree of Knowledge, and there are “general commandments” like “be fruitful and multiply”. Further on in the book there are commandments to Noach and his sons when they leave the ark, including a second command to “be fruitful and multiply” which is reiterated to Yaakov. Avraham is commanded to circumcise himself and his household. And so on. Additionally, the Book of Bereishit alludes to a number of halakhic institutions (such as yibum – levirate marriage – and mohar – bride price). 

Let’s focus on the commandments we call Sheva Mitzvot Bnei Noach – the Seven Commandments of the Sons of Noach, also known as the Seven Noahide Laws. What are these seven commandments?

As a memory aid they are often grouped into the “big three” – prohibitions against idolatry, licentious relations, and murder – and the achronysm אבג”ד which stands for three prohibitions against the consumption of limb or flesh of a live animal, “blessing” God (a euphemism for blasphemy), stealing, and a positive commandment to set up a judicial system.

Where do these laws come from?

At first one might think that since these are referred to as the Seven Commandments of the Sons of Noach they must appear as commands to Noach and his sons. Indeed, there are rabbinic midrashim that extrapolate the source of these commandments by expounding on the verses that contain explicit commands to Noach and his sons (Bereishit Chapter 9:1, 4-6):

God blessed Noach and his sons, saying: You shall be fruitful and multiply and fill the land… But you may not eat flesh with its life-blood in it. But your life-blood I will demand, from each animal I will demand, and from each human, each person from their fellow I will demand the life of a human. One who sheds human blood shall have their blood shed by a human, for humankind was created in the image of God. And you shall be fruitful and multiply and teem upon the land and multiply in it.

This approach is problematic as it is difficult to find a source for all seven commandments in these verses. Murder is explicitly forbidden, and one could claim that the prohibition against eating blood can also be understood as eating from an animal that is still alive. “One who sheds human blood shall have their blood shed by a human” may indicate that there must be a judicial system that can execute murderers. If we want to be creative we can say that “be fruitful and multiply” hints at a proper way to do so and prohibits licentious unions. And, as we will see in the next midrash, one could argue that the fact that God commands is based on the principle that God is our Master and must be respected; therefore one may not serve false gods or blaspheme. 

Indeed, it is not easy to find a source for each of the Seven Noahide Laws in these commandments to Noach’s sons. For example, we weren’t able to find a source for the prohibition of theft. 

Rabbi Yochanan (TB Sanhedrin 56a-60b) looks for the source of the prohibitions earlier, in God’s commandment to Adam not to eat from the Tree of Knowledge:

Rabbi Yochanan said: The verse (Bereishit 2:16) says ‘The Lord God commanded Adam saying eat from every tree of the garden…’

Commanded – this refers to judicial laws (dinim), as it says (Bereishit 18:19), ‘For I know him in order that he will command his sons after him…’

The Lord – this refers to blaspheming, as it says (Vayikra 24:16), ‘One who blasphemes the Name shall be put to death’.

God – this refers to worship of foreign gods, as it says (Shmot 20:2-3), ‘You shall not have other gods’.

Adam – this refers to spilling blood (murder), as it says (Bereishit 9:6), ‘One who spills human blood…’

Saying – this refers to immoral sexual relationships, as it says (Yiriyahu 3:1), ‘Saying when a man sends his wife away and she leaves him and is with another man…’

From every tree in the garden – and not something stolen.

Eat – and not flesh from a living animal…

Rabbi Yochanan expounds on the Divine commands to Adam to find the source of the “Noahide” laws. Though we refer to “commandments of the sons of Noach”, Rabbi Yochanan applies this term to humankind, which was originally “sons of Adam” (bnei Adam) but became “sons of Noach” after the flood. Some of his drashot (expounding and probing of the text) are far from the plain meaning of the text, but they do connect to a greater midrashic landscape. The Tree of Knowledge is often connected to sexuality (and limitations on food are often compared to sexual limitations). As mentioned earlier, the idea that the very existence of a Divine command is proof that one may not worship false gods (or blaspheme). Defining what objects are permitted or prohibited for use relates to laws of ownership and theft. The source for eiver min hachai is interesting, considering that at this time humankind was not permitted to eat animals at all.

What do these drashot have in common? They are both based on the assumption that these commandments can be found in Divine commands in the text.  They debate the timing of the commands – does the phrase “sons of Noach” refer to the time the commands were given – to Noach and his sons? Or were these commandments given to Adam and continue to apply after the flood when humankind became “sons of Noach”. Nevertheless they fundamentally agree that if there is an obligation, there must be a commandment.

The continuation of the gemara above hints at a different source for these laws, relating that the story of the flood demonstrates the transgression of some of these prohibitions. “For all flesh had corrupted its way on the land”. (Bereishit 6:12) Rabbi Yishmael teaches that when the Torah uses the term “corrupt” it refers to worship of false Gods or licentious unions. If the devastating flood was a result of licentious behavior (as described in the previous chapter when the B’nei Elohim took from themselves daughters of man as they pleased), and theft (“the land was full of thievery” according to Rashi), then these acts must have been prohibited. Therefore, it seems that there is another possible source for the Noahide Laws – the stories of Bereishit.

In a similar vein we can add that if Kayin was punished for Hevel’s murder then murder must have been prohibited. If an entire generation was punished for waging war against Heaven, trying to “make a name” for themselves and rebelling against God with the Tower of Babel, it is clear that serving anything but God is a grave sin. If Avimelech, the King of Gerar, is punished for taking Sarah then adultery is forbidden. Sodom, as opposed to Avraham, was devoid of justice and righteousness and consequently destroyed, indicating that they had an obligation to act justly. 

If the source of the Seven Noahide Laws can be found in these stories then it’s possible to claim that explicit commandments aren’t necessary – some acts are clearly right, some clearly wrong. Certain behaviors  are logical imperatives and it’s legitimate to say “you should have figured it out on your own”.

The search for the source of the Seven Noahide Laws can be understood as an attempt to understand the essence of these obligations and moral behavior in general. This dispute dates back to the times of Chazal and continues to this day. And it is closely related to a more fundamental question: Must humankind receive an explicit Divine command to understand and be obligated in moral behavior, or perhaps there are some moral behaviors that simple logic demands of us (“you should have known better”)? 

Scholars have debated this question through the ages. We also find many sages who maintain that while there is an independent human capacity for moral obligation, such behaviors are elevated when one adheres to them due to a deep commitment to God and God’s commandments.

Rabbanit Dr. Adina Sternberg

has a B.A. in Bible from Hebrew University and a M.A. and Ph.D. in Talmud from Bar Ilan University. Adina studied in Midreshet Lindenbaum, Migdal Oz, Havruta and the Advanced Talmud Institute in Matan. She currently teaches Bible and Talmud at Matan, and Efrata and Orot colleges. Adina lives in Adam (Geva Binyamin) with her family.