Mishneh Torah, Sabbath 28

Sugya Map

• Issue: Defining the halachic boundaries of a city for the purpose of the 2,000-cubit techum shabbat (Sabbath limit).
• Core Question: When does a peripheral structure—a house, a cave, or a bridge—cease to be an "outlier" and become an organic part of the city, thereby shifting the "zero point" from which the techum is measured?
• Nafka Mina: The legal status of suburban sprawl. If a series of houses exists, does the techum expand outward like a ripple effect, or is there a hard limit to "city-hood"?
• Primary Sources: Eruvin 55b-59a; Mishneh Torah, Sabbath 28; Orach Chayim 398-399.

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Text Snapshot

The Rambam opens with the foundational calculation:

"Whenever there is a home that is outside a city, but seventy and two thirds cubits... or less from the city, it is considered to be part of the city and joined to it." Mishneh Torah, Sabbath 28:1

The nuance lies in the phrase mitztaref la-medinah (joined to the city). The Rambam uses the seventy and two-thirds measurement, derived from the karpef of the Tabernacle's courtyard (Exodus 27:18), to define the "buffer zone." The dikduk here is critical: the Rambam is not merely describing proximity but legal incorporation. Once the condition is met, the house acts as a new "corner" of the city, effectively creating a square around the entire cluster.

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Readings

The Ohr Sameach: The "Square" Geometry

The Ohr Sameach (on 28:1:1) probes the underlying rationale of these 70 and 2/3 cubits. He contrasts the Yerushalmi’s approach with the Babylonian tradition. He notes that the Tosefta suggests this specific measurement is not an arbitrary distance, but a geometric requirement to ensure the city functions as a tavla meruba'at (a squared tablet).

The Ohr Sameach’s chiddush is that even a small city, which lacks the physical dimensions to necessitate a large expansion, must be treated as a "square" in the eyes of the law. The peripheral houses provide the necessary points to complete the geometry of the square. Without these, the city remains a point; with them, it becomes a defined area. The "city" is not defined by its walls, but by its geometric potential to be enclosed within a square.

The Maggid Mishneh: The "Stringency of Status"

The Maggid Mishneh (on 28:1) focuses on the status of these structures. He distinguishes between "dwellings" and "non-dwellings" (like bridges or graves). His chiddush is that the "dwelling" requirement is not merely for utility—it is a marker of yishuv (settlement).

He argues that the reason the Rambam is so exhaustive in his list (synagogues, false-deity temples, etc.) is to clarify that the techum is a social construct. A bridge, if inhabited by a toll collector, becomes a "dwelling" because it is a place of human occupation. The Maggid Mishneh reconciles the Rambam with the Ra’avad by asserting that the techum boundary is an extension of human presence, not physical infrastructure. If the humans reside there, the "city" has migrated.

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Friction

The Kushya: The "Infinite Chain" Paradox

The Rambam states: "If one house is within seventy cubits of a city, another house is within seventy cubits of the first, and a third within seventy cubits of the second... they are all considered to be one city, although the chain extends for a distance of several days walk." Mishneh Torah, Sabbath 28:2.

This creates a massive kushya: If the chain is theoretically infinite, does a house 50 miles away from the city center count as part of the "city"? This seems to dismantle the very definition of a "city" as a localized municipality.

The Terutz

The terutz lies in the interplay between halachic incorporation and geographic reality. The Rambam assumes that a "city" is a functional unit. While the law allows for a chain, this chain presupposes continuous habitation. If any link in the chain is broken (i.e., a gap > 70 and 2/3 cubits), the chain shatters. The "infinite" nature is a mathematical abstraction—a halachic city is defined by the continuity of the habitation, not the distance from the original urban core. Thus, the city grows organically; it does not "teleport."

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Intertext

• Parallels: The concept of the karpef (70 and 2/3 cubits) is inextricably linked to the layout of the Mishkan courtyard. See Numbers 35:5, where the Levite cities are prescribed a surrounding space (migrash), which the Gemara explicitly links to these Sabbath measurements in Eruvin 56a.
• Responsa: The Chatam Sofer (Responsa Orach Chayim 94) provides a rigorous mathematical defense of the Rambam regarding the "triangle" of villages. He argues that we must visualize the city as a "bounding box," and the techum is simply the expansion of that box by 2,000 cubits in every cardinal direction. He rejects any interpretation that allows for "fuzzy" borders, demanding that the "square" be calculated with the precision of a land surveyor.

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Psak/Practice

In modern practice, the techum shabbat is rarely calculated via the "chain of houses" method in urban settings, as the tzurat ha-petach and existing municipal borders usually define the techum. However, the heuristic remains: the city boundary is not the "city limit" sign, but the outer edge of the continuous residential zone.

Heuristic for the practitioner: When determining your techum, identify the last permanent dwelling (4x4 cubits). Do not look at the map for municipal lines; look for the "inhabited footprint." Any gap greater than 70 and 2/3 cubits breaks the techum chain, rendering the outlying structure an independent entity (or a makom petur), effectively resetting your 2,000-cubit allowance.

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Takeaway

The city is not a legal fiction of a government, but an organic expansion of human dwelling; as long as the space between us is bridged by life, the city continues.