Bava Batra 89

On Kiddushin 40, we learned from a beraita:

A person should always view themself as though they were exactly half-liable and half-meritorious, meaning they should act as though the plates of their scale are balanced, so that if they perform one mitzvah they are fortunate, as they tilt their balance to the scale of merit. If they transgress one prohibition, woe to them, as they tilt their balance to the scale of liability.

In our day, double pan scales are a visual metaphor for balance and justice but we rarely, if at all, use them to determine how much something weighs. Not so for the rabbis who used them frequently in the market. Today’s daf describes standard weights that would be used with them:

The sages taught: If the buyer requested from the seller a litra of a specific item, he weighs for him using a litra weight. If he asks for half a litra, he weighs for him using a half-litra weight. If he wants one-quarter of a litra, he weighs for him using a quarter-litra weight. 

This beraita mentions three standard size weights: whole, half and quarter litra. If someone wants to buy, say, three quarters of a litra, the merchant has to get a bit more creative. The Gemara brings a beraita that notes there are multiple ways to weigh this amount out:

If the buyer requested from him three-quarters of a litra, the buyer may not say to the merchant: “Weigh for me three units using a quarter-litra weight, one by one.” Rather, the merchant weighs the merchandise all at once, placing a litra weight on one pan of the scale, and a quarter-litra weight on the other pan of the scale together with the meat that is being sold.

Even though it’s true that the second method is more efficient than the first (one weighing instead of three), both approaches yield the same result. So why does the beraita have such a strong preference for one of them? It has to do with a requirement found in the mishnah currently under discussion, which declares:

The seller is obligated to let the pans of the scale that will hold the merchandise tilt an extra handbreadth for the buyer.

While biblical and rabbinic law demand that the seller maintain honest weights and measures, the technology of the day did not allow for perfect measurement: scales could be a bit unbalanced (either intentionally or not) and weights might be inaccurate. To compensate for this, and because the weighing equipment usually belongs to the seller, the mishnah protects the buyer by having the merchant add a little extra to the scale so that it tips one handbreadth to the buyer’s side. This acknowledges there is some error in each transaction. It follows that if a transaction employs three weighings, instead of one, the error multiplies and the buyer may end up with a full three extra handbreadths instead of one. So, to protect the seller, the beraita acts as a counterbalance (pun intended!) to the mishnah, and stipulates that the minimum number of weighings must be utilized. In doing so, the Talmud also makes the case for a well-balanced education for jurists — you need both mathematics and ethics to balance the scales of justice.

Read all of Bava Batra 89 on Sefaria.

This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on September 22, 2024. If you are interested in receiving the newsletter, sign up here.