Rashi, Tosafot, and a Proof from a Nonexistent Object
A student, Miriam, is writing a source-based essay on the principle 'אין אדם מקנה דבר שלא בא לעולם'. She finds a sugya in which a person says to his neighbor, 'The fruit that my tree will produce next year is sold to you for 100 dinars.' The Gemara initially suggests the sale is invalid because the fruit is not yet in the world. It then cites a baraita: 'One who says to a woman, "Your daughter whom you will bear is betrothed to my son"-the betrothal is valid.' Rashi explains that the baraita is a special gezerat ha-katuv and does not change the general rule. Tosafot asks: if so, why does the Gemara use the baraita to resolve the fruit case? Tosafot answers: 'שאני התם דמשעבד נפשיה'-there the father obligates himself personally, which is different from transferring ownership of a nonexistent object. Miriam must decide which explanation to present as peshat and how to handle the disagreement in her essay.
1. Reconstruct Tosafot's question and answer. What exactly does 'משעבד נפשיה' add?
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Tosafot's question is a proof problem. Rashi says the betrothal baraita is a special gezerat ha-katuv. If it is special, it cannot serve as a general proof that one may transfer a nonexistent object. Yet the Gemara cites it to resolve the fruit case. Tosafot answers that the baraita is not about transferring ownership of a nonexistent object at all. The father is not selling his future daughter; he is obligating himself personally to a condition. 'משעבד נפשיה' means he creates a personal bond or obligation that can take effect even regarding a future entity. That is different from saying, 'The fruit itself is transferred now,' which would be a transfer of a thing not yet in the world. Tosafot's answer thus preserves the baraita as a relevant proof without turning it into a special exception. The key move is distinguishing personal obligation (shibud) from proprietary transfer (kinyan). A good answer should show that Tosafot is not denying Rashi's general principle; he is narrowing the baraita's legal mechanism.
2. How might Rashi respond to Tosafot without abandoning his reading?
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Rashi could respond in two ways. First, he could argue that the Gemara uses the baraita only as a support, not as a strict proof: it shows that the Torah sometimes recognizes obligations concerning future entities, which makes the fruit case less absurd, even if the two cases are not identical. Second, he could accept Tosafot's distinction but deny that it is the Gemara's point. On Rashi's reading, the baraita remains a gezerat ha-katuv; the fruit case is still governed by the general rule, and the Gemara's citation is a rhetorical comparison. Rashi might also challenge Tosafot's assumption that 'משעבד נפשיה' is explicit in the baraita. If the baraita does not mention personal obligation, Tosafot is importing a concept. Rashi's reading is more literal about the special rule; Tosafot's reading is more integrative. The exam answer should not simply say 'Rashi is old and Tosafot is new.' It should show how each commentator allocates the burden of explanation.
3. Which explanation is more persuasive for the sugya's conclusion, and what textual evidence would change your mind?
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Tosafot is more persuasive as peshat if the Gemara actually uses the baraita as a proof for the fruit case. A special gezerat ha-katuv cannot prove a general principle, so Rashi's reading leaves the Gemara's citation unexplained. Tosafot's distinction between personal obligation and proprietary transfer explains why the baraita is relevant without abandoning the rule. Rashi remains persuasive if the Gemara's conclusion explicitly calls the baraita a 'גזירת הכתוב' or if the sugya treats the two cases as analogous on the surface. What would change my mind is the exact wording of the conclusion: does the Gemara say 'שאני התם' or 'התם גזירת הכתוב היא'? Does the baraita mention the father's personal obligation? Does the fruit case involve a personal obligation as well? The essay should present Tosafot as the more integrative reading and Rashi as the more literal one, then state which fits the immediate sugya.