Q&A: Half of the Legal Derivation
Half of the Legal Derivation
Question
Hello. In tractate Bava Kamma 5a, Rashi says that when we want to derive all the primary categories of damages from Pit and Fire, one can derive Man and Foot by means of “half of the legal derivation.” Tosafot, in their comments on Rashi, say that besides the possibility of deriving by “half of the legal derivation,” one can derive them from Fire alone. How did Tosafot understand Rashi’s concept of “half of the legal derivation”? And in general, what is “half of the legal derivation” in relation to the ordinary method of derivation through a paradigm case? I would appreciate as much elaboration as you can give. Thank you.
Answer
As I understand it, this is a derivation from the common denominator of two primary categories: Pit and Fire. A derivation by “half of the legal derivation” means a derivation from half of the two source categories, and in this case, from Fire alone. Regarding Tooth, Rashi explains there that you need both source categories, because Fire is predisposed to consume even that which is not fit for it, unlike Tooth. But Foot and Man are predisposed to damage anything, and therefore they can be derived from Fire alone. You do not need the addition of Pit.
Tosafot disagree with Rashi, and in their view Tooth too can be derived from Fire alone, because with Tooth, by definition, eating something unfit is not relevant; if it consumed something unfit for it, that is Horn, not Tooth. According to this, the combination of Pit and Fire is unnecessary. Fire alone does all the work. And that is the derivation of all the other primary categories by “half of the legal derivation.”
Tosafot’s concluding formulation is:
“And it appears that Tooth as well comes by half of the legal derivation, or from Fire alone.”
In truth, at first glance it is not clear why Tosafot add “half of the legal derivation” or “from Fire.” Seemingly, that is the same thing. It may be that this is simply an explanation of the term “half of the legal derivation” — that is, from Fire alone. Therefore it seems more likely that the point is to sharpen the difference between their view and Rashi’s. To understand this, we should first explain why Rashi calls this “half of the legal derivation” and not simply a derivation from Fire. The explanation is that according to Rashi, Man and Foot can be derived only from the two primary categories together, and therefore in any case both must be written. Only Tooth is derived from Fire alone, and that is what is called a derivation by “half of the legal derivation.” But according to Tosafot, Tooth too can be derived from Fire alone, and so on their approach it is enough to write Fire alone. And once Fire alone is written and everything is derived from it, that is no longer “half of the legal derivation” but simply a derivation from Fire.
A derivation by “half of the legal derivation” exists only in a situation where both primary categories must be written (Pit and Fire), but there is one of the derivative categories (Tooth) for which half of the two is enough, while for the other primary categories (Man and Foot) both are needed. But when, generally speaking, it is enough for us to write Fire alone and everything is derived from it, that is a derivation from Fire, and it is not appropriate to call it a derivation by “half of the legal derivation.”
Discussion on Answer
“The explanation is that according to Rashi, Man and Foot can be derived only from the two primary categories together, and therefore in any case both must be written. Only Tooth is derived from Fire alone” — it should say the opposite.
Is there support for the idea that the word “or” can be used in the sense of an explanation?
The Rashba: “. Or alternatively, it is not to say that when you place Pit among each one of them, all of them come from every pair; rather, from any two, provided that Pit is one of them.” And it would seem that this is how Tosafot read the Talmudic passage.
As for their difficulty on Rashi, it seems that this is a dispute about how to understand “not fit.”
Indeed, the opposite.
The tanna’im disagreed whether “or” is interpreted as equivalent to “and” or not (conjunction or disjunction). If it is like “or,” there may perhaps be room to read it as an explanation: half of the legal derivation, or (= that is) Fire alone. But, as I said, the latter is the main point.
I didn’t understand what you brought from the Rashba. According to Tosafot, everything can be derived from Fire alone.
Exactly.
Where is the dispute among the tanna’im?
The Rashba says that “when you place Pit between them and all of them come from them” does not mean that all of them come from the two together, but rather even from one of the two — that is, from Fire. The need to mention Pit is only because it cannot be derived in any other way. The derivation of all the primary categories becomes possible when Fire and Pit are written, but not necessarily from the combination of the two.
Of course, the Talmud according to Tosafot is puzzling. Instead of saying that from Pit and one of them you can derive everything, they should have brought Fire alone. His difficulty on Rashi, on the other hand, can easily be resolved.