On the one hand we know that if a Sanhedrin issued an erroneous decision (which was acted upon) they must bring a sacrifice (Vayikra 4:13).

On the other, we have the concept of "lo bashamayim hi" (see also: Bava Metzia 59b) namely that the meaning of Torah is decided not in Heaven, but by Rabbinical interpretation here on Earth. And Sanhedrin seems like the ultimate interpreting body.

So how then can the Sanhedrin ever err? I'm not talking about errors in matters of metzius (such as, husband went away on journey, they thought he was dead, but he came back alive). Rather, I mean errors in interpreting the Torah - what should be permissible and what should be forbidden. It seems that whatever the Sanhedrin decides, is correct or becomes correct, by definition (due to "lo bashamayim hi").

If we say they can err, that implies the existence of an independent standard of truth, against which errors can be made. Which would go against "lo bashamayim hi".

  • 1
    Who says vayikra 4:13 is talking about rabbinical items
    – Dr. Shmuel
    Apr 1, 2019 at 19:41
  • Heavily related: judaism.stackexchange.com/q/69800. See my answer there, where I propose that your deduction is actually correct: whatever the Sanhedrin rule indeed becomes the Halacha l’Maaseh.
    – DonielF
    Apr 2, 2019 at 1:17
  • Why was the existing answer (and comments on it) deleted?
    – Meir
    Apr 2, 2019 at 15:02
  • I would also like to know...
    – user9806
    Apr 2, 2019 at 17:18
  • The existing answer was perfectly valid and relevant, and had instructive comments. Why was it deleted, and how come there is no history or explanation of the deletion?
    – user9806
    Apr 2, 2019 at 17:28

3 Answers 3


Imagine a scenario where a king orders his subjects to sort unlabeled boxes of two types of objects into each of two rooms. The subjects are forbidden to open the boxes but instructed instead to seek the guidance of the king's appointed elders as to which boxes contain which objects.

The elders use various sophisticated, best efforts means to guess at the boxes' contents. Occasionally, the elders may change their minds as to which are the contents of a given box, such as in response to new evidence or just a fresh perspective, and that box will then be reclassified and sent to the other room.

Contrast this scenario with one where the boxes are known to be empty and the king has instructed his servants to fill the boxes with whatever the elders think are in them. Wouldn't the wise of the elders just acknowledge that the boxes are empty and not waste time trying to pretend that the evidence points one way or the other?

I think therefore that it's pretty clear that the latter scenario does not at all represent the halachic process. Rather, the wise King knows that the subjects are human and only requires them to listen to their elders, as is reasonable. Likewise, He knows the elders are fallible humans as well, and only requires a level of effort to guess at the contents. Practical halacha thus follows the ruling of the Sanhedrin, provided one's knowledge is no greater than their own (see e.g. Horayoth 2a-2b where a student who follows the guidance of the Sanhedrin, knowing they are in error, has to bring his own personal offering for his mistake in listening to them, and is not atoned with the communal offering they bring for their error, which does indeed atone for the error of the unwitting masses.

This idea is what is meant in the passage in Bava Metzia:

עמד רבי יהושע על רגליו ואמר (דברים ל, יב) לא בשמים היא מאי לא בשמים היא אמר רבי ירמיה שכבר נתנה תורה מהר סיני אין אנו משגיחין בבת קול שכבר כתבת בהר סיני בתורה (שמות כג, ב) אחרי רבים להטות

Rabbi Yehoshua stood on his feet and said: It is written: “It is not in heaven” (Deuteronomy 30:12). The Gemara asks: What is the relevance of the phrase “It is not in heaven” in this context? Rabbi Yirmeya says: Since the Torah was already given at Mount Sinai, we do not regard a Divine Voice, as You already wrote at Mount Sinai, in the Torah: “After a majority to incline” (Exodus 23:2). Since the majority of Rabbis disagreed with Rabbi Eliezer’s opinion, the halakha is not ruled in accordance with his opinion.

The Torah was given over with rules regarding the determination of practical halacha. These rules include following the majority. They do not include following a bat kol. As per the ruling of the King, even if the bat kol is assumed to describe the actual contents of the box, its testimony is inadmissible in the court of halachic determination. If the sages, however, change their minds, they may then require a par he'elam davar based on their new opinion. (And perhaps at times another one if they change their minds again.)


The premise behind this question seems to be that whatever Sanhedrin decides ipso facto becomes the Halacha and the reality because Lo B'Shmoyim Hi.

However, Lo B'Shmoyim Hi isn't really such a broad concept. If something is unclear and there are legitimate ways to rule either way then yes Lo B'Shmoyim Hi, we will go with whatever the understanding of Sanhedrin is and that will become Halacha.

If however they make a mistake and yes they are capable of doing so then the mistake will remain a mistake and will have to be undone with a Korbon brought afterward.

IOW Lo B'Shmoyim Hi is just another guideline of how they reach a ruling in most cases where they presumably aren't making a mistake. It would not be relevant in a case where it can be proven that they were.


Congrats! You've just found the dual nature of Judaism - it can be true and false at the same time!

Seriously, what you confuse is relative and absolute Halachah. When it is relative - Rabbis have the privilege to set the Halacha de-jure but when they refer to the "absolute" Halacha (like a Mishnah or the like), the Rabbis can be wrong.

THe Gemmorah in Sanhedrin (33) says "טועה בדבר משנה" for example as a criterion for invalidating a Psak. So when the Sanhedrin "invents" new Halochos they can not be possibly wrong, but when they "develop" existing ones they can start with a wrong assumption that contradicts a Mishna they forgot and that will knock the whole Psak down.

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