Mishnah Kelim 7:2-3

Sugya Map

• Primary Issue: The classification of the Duchan (hob/extension) attached to a Kirah (stove). Does it function as a Kirah (an oven-component, subject to its own unique laws of impurity) or as a Kli Kibbul (a vessel with a receptacle, subject to standard vessel-impurity rules)?
• Nafka Mina:
  1. Mechubar L’karka: If the Duchan is fixed to the ground, it cannot contract impurity as a Kli (vessel), but it might as a Kirah.
  2. Bitul: Does the Duchan become batel (nullified/subsumed) to the Kirah, sharing its status, or does it maintain a distinct identity?
  3. Shiurim: Does the "air-space" (toch) of the Duchan act like a vessel’s interior, or does it follow the more lenient Kirah standards?
• Primary Sources: Mishnah Kelim 7:2–3; Tosefta Kelim Bava Metzia 5:6; Rambam, Hilchot Kelim 15:1–3.

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Text Snapshot

The Mishnah (7:2) introduces the Duchan (דכון) as a structure with a beit kibbul kederot (בית קבול קדירות) — a receptacle for pots.

• The Nuance: The term Duchan is glossed by Rash (s.v. Duchan) as loshon makom (place/platform), linking it to the duchan of the Temple. The dikduk here is critical: the Mishnah distinguishes between being tahor (clean) mishum kirah (by reason of the stove) and tamei (unclean) mishum kli kibbul (by reason of a vessel).
• Crux: If it is a Kirah, it is subject to the stove’s specific thresholds of impurity. If it is a Kli, it is a vessel, susceptible to tuma’ah regardless of its connection to the stove, provided it is taluya (detachable/mobile).

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Readings: Rishonim and Acharonim

1. Rambam: The Functionalist Approach

Rambam (Comm. ad loc.) provides the most robust definition of the Duchan. He describes it as a rectangular ceramic structure, hollowed out, with circular holes in the surface. One fills it with hot ash to keep the pots sitting on the holes warm.

• The Chiddush: Rambam distinguishes sharply between the Duchan as a Kli Kibbul and as a Kirah. If it is built into the ground, it escapes Kli impurity (as it is no longer a "vessel"). However, its status as a Kirah remains active if it functions as one. The critical pivot is the shiur of the receptacle. If the Duchan is modified—such that the receptacle is breached—it loses Kli status. But, says Rambam, the Kirah status is more resilient. The Duchan is a hybrid; its impurity is determined by its current function. If it’s used for cooking, it’s a Kirah; if it’s a mere receptacle, it’s a Kli.

2. Rash MiShantz: The Spatial/Structural Approach

Rash (s.v. Duchan) shifts the focus to the b'litah (protrusion). He suggests the Duchan is essentially an extension of the Kirah’s surface.

• The Chiddush: Rash utilizes the Tosefta to argue that the Duchan’s status is contingent upon the intent of the owner. A Duchan of a householder—meant for utility—is treated differently than that of an Ullayarin (bathhouse attendant), which is built simply for the ground and never meant to be a Kli. The Duchan is a shmua (a piece of furniture) that acts as an appendage. If it is connected to a Kirah, it might be considered part of the Kirah’s body (gufah), but if the Duchan is structurally distinct, it is a Kli in its own right. This creates a "dual-status" object: it is a Kirah relative to the stove, but a Kli relative to the pot it holds.

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Friction: The Strongest Kushya

The Kushya: How can an object be tahor as a Kirah but tamei as a Kli (Kelim 7:2)? If the Duchan is physically part of the Kirah, the Kirah’s status should dictate the Duchan’s status. If the Kirah is tahor, the Duchan should be tahor. If it is tamei, the Duchan should be tamei. Why does the Mishnah bifurcate the impurity?

The Terutz:

1. Rambam’s Resolution: The Duchan is not actually a Kirah; it is merely treated as one. The Kirah is a functional category of oven-ware. The Duchan occupies a space of "functional mimicry." If it is used to hold pots, it mimics the Kirah’s utility but maintains the Kli’s definition.
2. Yachin’s Resolution: Yachin (ad loc.) argues that the Duchan is a chibur (connection) in a halachic sense but not a physical one. Since it doesn’t serve the Kirah’s specific purpose of baking/cooking (it only keeps things warm), it is legally separate. Thus, when the Kirah is tamei, the Duchan remains unaffected because they aren't a single tuma unit; they are separate entities sitting adjacent to one another.

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Intertext: Parallels and Cross-refs

• Shabbat 38a: The Gemara discusses the Kirah and the Kupach. The Kirah is defined by the fact that it is meant for cooking. The Duchan is essentially a Kupach-like extension. The Sages’ concern with the Duchan reflects the broader concern in Kelim regarding chiburim (connections) that are not permanent.
• SA, Yoreh De'ah 158: While the laws of Kelim have diminished in practice, the logic of chiburim (what constitutes a single vessel versus two separate ones) remains the foundation for Tevilat Kelim. The Duchan logic—that an attachment can change the status of an object—is echoed in the discussions of tashmishim (accessories) to Kelim.

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Psak/Practice

In modern Halacha, these principles inform the meta-psak regarding Kashering and Tevilah. If an appliance has a modular part (like a stove burner tray), we ask: Is it b’tel to the stove (part of the Kirah) or is it a separate Kli? If it is a separate Kli, it requires tevilah and has its own tuma status. The Duchan teaches us that functional proximity does not automatically equate to halachic unity.

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Takeaway

The Duchan is a lesson in ontological ambiguity: it is a Kirah by utility, but a Kli by form. Halacha respects the physical integrity of the object over the convenience of a unified status.