Eruvin 14

The wisdom of crowds.

James Surowiecki’s 2014 bestseller, “The Wisdom of Crowds,” advances the theory that the collective problem-solving of crowds often produces more accurate results than small groups of experts. Even if you haven’t read it, you may have benefited from its key ideas if you ever crowdsourced a recommendation on Facebook.

Surowiecki attributes some of his thinking to the work of Sir Francis Galton, a 19th-century English scholar. But he probably didn’t know that aspects of his theory have even earlier roots — notably in a rabbinic idea we encounter on today’s daf.

The mishnah discusses the size requirements for lchi’in (לְחָיַיִן), the side posts that are used to create a doorway of sorts that permits one to carry in a three-sided alleyway on Shabbat. Naturally, there is a dispute. The mishnah says the posts may be any width, but Rabbi Yosei believes they must be at least three handbreadths wide. There is a fair amount of confusion in the Gemara about Rabbi Yosei’s position and how it was transmitted over the centuries, which impedes the rabbis’ ability to figure out the law. The

Eventually, the discussion ends with this:

Rava bar Rav Ḥanan said to Abaye: What is the accepted halakha with regard to the width of a side post? He said to him: Go out and observe what the people are doing; it is common practice to rely on a side post of minimal width.

This phrase “go out and see what the people are doing” — pok hazi mai ama davar, in the original — is a striking way to end a legal discourse. Normally, the rabbis try to argue out the law through intellectually rigorous reasoning. But here (and in 13 other places in the entire Talmud) they decide to determine the law by going out into the community and seeing what the Jewish people are doing.

This concept is predicated on the assumption that the communal practice reflects a faithfully transmitted tradition. Had Rava bar Rav Hanan gone out and found that the people were carrying in an open area on Shabbat — a direct violation of biblical law — such behavior would surely not have become permitted. But once the rabbis assume that the common practice is derived from an established source, they can confirm the law on that basis, even if the process by which that position was reached isn’t clear and even if they can’t reason it out for themselves.

The incredible implication of this principle is that there is wisdom in the crowd that supersedes the wisdom of the sages. This is true even if the crowd isn’t aware of where this wisdom comes from. Abaya doesn’t tell Rava bar Rav Hanan to go and ask the people why this is their practice. He simply says to go and see what the people do and this will be the law.

The notion of pok hazi invites us to consider the dialectical nature of Jewish law, the interplay between intellectual reasoning and lived reality, and how the collective knowledge that informs our practice can sometimes be more accurate than the most brilliant of minds.

So the next time you crowdsource a recommendation to help you make a decision, or let the starred ratings inform your Amazon purchase, don’t forget to thank Abaye and his directive to pok hazi — go and see!

Read all of Eruvin 14 on Sefaria.

This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on August 23, 2020. If you are interested in receiving the newsletter, sign up here.

Discover More

Tisha B’Av FAQ

Your questions about the Jewish day of mourning answered.

Sumac Chicken and Rice Recipe

This go-to chicken and rice dish looks gorgeous, tastes incredible, comes together in no time, and you can make it all in one pan.

Hair Coverings for Married Women

Why some Orthodox women cover their hair, whether with wigs, hats or scarves.