Mishneh Torah, Sabbath 18

Sugya Map: The Paradox of Chatzi Shiur

• Issue: Does the prohibition of Chatzi Shiur (half-measure) apply to Hotza’ah (transferring on Shabbat)?
• Nafka Mina: Whether transferring less than the defined measure is a Torah-level violation (Issur D'oraita) or merely Rabbinic (Derabanan).
• Primary Sources: Mishneh Torah, Sabbath 18:1; Shabbat 74a; Mishneh LaMelech, Hilchot Shabbat 18:1; Yitzchak Yeranen (ad loc).

Text Snapshot

Rambam states: "A person who transfers an article... is not liable (patur), unless he transfers an amount that will be beneficial." Note the terminology: Rambam consistently uses patur here, which, per his introduction to Sefer Zemanim, usually implies a Rabbinic prohibition. However, the Mishneh LaMelech argues that Chatzi Shiur is inherently prohibited by the Torah, contradicting the Rambam's own framing of patur.

Readings

1. Mishneh LaMelech: Argues that Chatzi Shiur is universally forbidden by Torah law. He asserts that the Rambam’s use of patur here doesn't mean it is permitted, but simply that it doesn't incur the chattat (sin offering).
2. Yitzchak Yeranen: Defends the Rambam by distinguishing between eating (where Chatzi Shiur is prohibited) and Hotza’ah. He suggests that because the act of Hotza’ah requires a completed action (Hanachah), transferring a partial amount doesn't reach the "Torah definition" of the act, hence the patur classification is precise and reflects a lack of D'oraita status.

Friction

• Kushya: If the Rambam holds that Chatzi Shiur is generally forbidden by the Torah (as he rules in Hilchot Ma'achalot Asurot 3:6), why does he imply it is only Rabbinic here?
• Terutz: The Yitzchak Yeranen posits that the act of Hotza’ah requires the creation of a "benefit" (tzorech). If the object is below the measure, it lacks the requisite utility to be considered a Melacha at all. Unlike eating, where the substance is consumed, Hotza’ah requires a functional transfer; if the object is insufficient to be "useful," the act is conceptually absent.

Intertext

• Shabbat 80a: Discusses the combination of two half-measures. The fact that the Gemara allows tziruf (combination) implies that the initial half-measure was not a complete issur in itself, mirroring the Rambam’s patur logic.

Psak/Practice

In practice, one never relies on the status of Chatzi Shiur to "allow" minor transfers on Shabbat. While the Mishneh LaMelech maintains it is an Issur D'oraita, the Rambam’s classification as patur (Rabbinic) informs the severity of the punishment, not the permissibility.

Takeaway

The measure of an object in Hotza’ah is not just a quantitative threshold; it is a qualitative requirement for Melacha. If the amount transferred is too small to be "beneficial," it fails the definition of "purposeful work" (Melechet Machshevet).