Commentary for Bava Metzia 4:21

As one can 'teach' and say: He teaches himself a dispensation to grab it unjustly.

If [the Mishna] taught [that one must take an oath only about] a lost object etc. Tosfos will add what is lacking in the language of the Gemara.
I would say that the Mishna requires an oath only when there is a dispute about a lost object, because one might rationalize his dishonest behavior by saying: My neighbor is not losing anything by my claiming that I picked it up first, after all, he did not invest any time or money in this venture. Therefore, [the culprit] will seize the garment even though he knows that his neighbor found it first. The Rabanan placed an oath upon him, so that he should desist from grabbing the garment and claiming that it is his. Even though he may be able to rationalize taking the garment from his neighbor, most people would not swear falsely in this situation.
However, when his neighbor was purchasing the garment, where this rationalization cannot be used, for if he actually knew that his neighbor purchased it first, he would not have seized it, because the neighbor did invest time and effort to locate this particular garment that he needs and the culprit would not do something that is so obviously wrong. Since he did seize it, he must believe that it is truly his and that the seller agreed to sell it to him, as [the Gemara] later concludes, that we are speaking of when the seller took money from both litigants. I might think that he should not swear when they are arguing about a purchase, because he will not desist from seizing the garment because of the requirement to take an oath, because he believes that he is telling the truth. The Mishna inform us that even so, he must swear. Since he is willing to pay for his share, he may not see his behavior as so despicable and can rationalize this as well. However, when faced with an oath he will desist.
Tosfos has explained that in both cases, a lost object and a purchase, there is room for rationalization. But what would we rule when one of the litigants is definitely lying and is about to steal from his neighbor?
When he definitely cannot be thinking that he is telling the truth, for example, when each one claims “I wove the garment”,¹See רש"י 2a ד'ה במקח ובממכרwho holds that in the case of each litigant claiming “I wove the garment”, there is no division at all. The garment is held in abeyance till Eliyahu will come and tell us who the rightful owner is. where one of them is intentionally falsifying his claim, or for example in the case of two litigants who are holding a document, the lender says: you still owe me the money and the borrower says: I have already paid. One is definitely lying, as there is no room for error. There it is plain that they must divide the garment with each litigant swearing, because through the oath the culprit will definitely desist from continuing his attempt to steal, because even one who is suspected of possibly stealing money, is not suspected of swearing falsely.

He is not lacking anything: He is not losing anything: It came to him for free, and even without exertion.

But, buying and selling, where that cannot be said: And even though this one also gave money to the seller - as we establish it later, that he took from both of them, one willingly and one against his will - and when they divide it, this one will take half of his money and that one will take half of his money; nevertheless it it a loss for him. For if he did not need it, he would not have sought it out, to buy it. And this one who is coming to divide [it] and to give half the money is unjustly causing him a loss.

I gave money: I want to give money.

But a found item, where it cannot be said: "Let me friend go and find another [like it]." This is certainly causing him a loss of money.

But let us see from whom he took: Let us ask the seller from whom he took the money. As we learned (in a baraita) in Kiddushin (73b), "A seller is deemed credible to say, 'I sold to this one, and I did not sell to that one.'" And even though it ends, "In [which case] are these words said? When his item that is being purchased is [still] in his hand. But if his item that is being purchased is not in his hand, he is not deemed credible." For he did not pay so much attention to the thing, that he would remember; since they both pursued him with the giving of its value. [Nevertheless,] we establish [the case] there to be when he took money from both of them, from one willingly, and from the other against his will. As since it is not incumbent upon him to testify, he was not so exacting to be careful after they went away from him [to remember, from] which one he was willing and [from] which one it was against his will. But when he only received money from one, he would certainly remember him.

Let us see from whom the seller took money. Let us first learn a Gemara in Kiddushin 73b that is relevant to understanding our Tosfos.
A seller is believed¹The Gemara does not clearly say why the seller is believed. There is a dispute among the Rishonim as is evident in this Tosfos. An understanding of this dispute will enable us to better understand the underlying movements of this Tosfos. See נחלת דוד for a lengthy exposition of this subject.
A) Rashi holds that the seller is believed because he is the only one that really knows the truth. There are similar situations in Kiddushin 73a, such as a midwife or a judge who are believed primarily because they are the only ones who know the truth. רש"י holds that the seller’s testimony is accepted for the same reason. Thus, according to Rashi as long as we are convinced that the seller actually does know to whom he sold the garment we believe him. If however, the situation is one where we have doubts about the seller’s knowledge, we do not believe him. Therefore, as long as the seller has possession of the garment, he has the responsibility to deliver the garment to the true purchaser. Even if the situation was somewhat confusing, such as when they both gave him money, he still must deliver the garment to the right party. However, as soon as he made his choice and no longer has that responsibility, we do not believe him when the conditions were confusing, but we do believe him when only one customer gave money.
B) Tosfos (Rabbeinu Tam) holds that the basis for believing the seller is that since the garment is in his possession he has a migo, that he could say that he did not sell the garment at all or that he repurchased it. We must therefore believe him when he says that I sold the garment to this one. Of course, this migo is operable only when the seller has the garment is his possession. Thus, after he releases it, we do not believe him at all. Rabbeinu Tam is compelled to say, as we will soon see, that our Gemara is asking that we should believe the seller, just as we believe any single witness. There is no special authority for the seller when he does not have the migo that he could maintain that he never sold the garment. to say: I sold to this one and not to that one. When is this so: When the sold item is still in [the seller’s] possession, but if the sold item is no longer in [the seller’s] possession, he is not believed. The Gemara asks: Let us see from whom he accepted money? Once we know who gave money, we will know that he is the true owner. Why must we rely on the testimony of the seller? No! This Baraisa is needed to teach us about when [the seller] accepted money from both and he tells us: From one I accepted willingly and from the other I accepted money against my will. It is not known from which customer he accepted the money willingly and from which customer he accepted the money against his will.
We can glean from that Gemara that the seller is believed when he still has possession of the article, but not when he has already given the item to the buyers. This presents a problem with our Gemara which asks: We should believe the seller? But in our Gemara the seller no longer has possession. The Mishna is speaking of when the two litigants are holding the garment. The seller has no special say in this matter since he no longer has possession.
רש"י anticipated this problem and explains our Gemara in view of what we have learned in Kiddushin 73b. Tosfos will first quote רש"י and then disagree with his conclusion.
Let us return for a moment to the Gemara in Kiddushin 73a. The Gemara says that we do not believe the seller when he no longer has possession. The Gemara immediately asks: Let us see from whom he accepted money. רש"י explains that the Gemara is asking, that since he received money from only one of the customers he most probably remembers which one it was and we should believe him even if he no longer has possession.²See preceding note. A) The Gemara essentially agrees with this proposal, but says that we are speaking of when the seller accepted money from both.
According to Rashi’s explanation, we may conclude that when he received money only from one of the customers, we believe him even when he no longer has possession of the article. First, let us see how רש"י reconciles our Gemara in Bava Metzia 2b with the Gemara in Kiddushin 73a.
רש"י explained our Gemara’s question: Let us ask the seller which of the litigants is the lawful owner of the disputed garment? Even though we have learned that the seller is not believed when he no longer has possession of the sold article, as can be seen in Perek Asarah Yuchsin (Kiddushin 73b), and our Mishna is speaking of when the seller does not have possession? That we do not believe the seller, was said when he accepted money from both customers, but when he accepted money from only one of the customers, he is believed even when the sold article is not in his possession. Our Gemara assumed that the seller most probably received money from only one of the customers and therefore says, let us see from whom the seller took the money. We would believe him if he said which customer gave him the money. The Gemara answers that our Mishna is speaking of when both gave money and we do not believe the seller who says: I accepted the money from this customer willingly.
According to this analysis of the Gemara, even if the seller who received money from both customers says he is certain that the garment belongs to this one, we do not believe him. We would believe him only if he had received money from only one of the customers.
In view of this analysis, we must take a better look at the next words of our Gemara. Our Gemara reads: ולא ידענא - I do not know. This seems to be a quote of the seller who is admitting that he does not know who the lawful owner is. רש"י quotes a text that reads ולא ידע - he, the seller, does not know. Again this implies that the seller tells us - I do not know who the lawful owner is. What if the seller says I do know? These texts lead us to believe that we would believe him. רש"י says that these texts are incorrect, because we have seen that the Gemara in Kiddushin 73b says that we do not believe a seller who accepted money from both customers.
רש"י therefore amends the text of our Gemara: Our text, after this statement of the Gemara that we are speaking of when the seller accepted money from both customers is: And we do not know. This means that even if the seller insists that he sold it to Ruvain, we do not accept his testimony and we, the court, do not know to whom the garment was sold. It is in this case that the Mishna rules that the garment is to be divided after each party swears.
After quoting רש"י, Tosfos offers his own explanation of our Gemara and insists that it is not necessary to amend the text. Rashi’s difficulty with our text is that the Gemara seems to be saying that we would believe the seller who says - I do know who the lawful buyer is, even if he accepted money from both customers. This is clearly contradicted by the Gemara in Kiddushin 73a.
Tosfos therefore explains that our Gemara’s question: “Let us see from whom he accepted money?”, is not about believing the seller as a special witness³See note 1, B), where I explained that Tosfos holds the authority of the seller is based on a migo, which he has when in possession of the garment, but not when he gives it away. in this matter. Rather, the question is - we should believe him as we would believe any single witness.
Although a single witness is not believed in money matters, he does have the power to compel a litigant to swear by Torah law. For example: If Ruvain claims that Shimon owes him one hundred zuz and Shimon denies it, by Torah law Shimon is exempt from paying and need not swear. If however, a single witness testifies that Shimon does owe the money, he is required to swear by Torah law.
According to Tosfos’ opinion he can also exempt any of the parties in a dispute from swearing. For example: If Ruvain claims that Shimon owes him one hundred zuz and Shimon admits that he owes him fifty zuz, by Torah law Shimon must swear that he only owes fifty zuz. If however, a single witness testifies that Shimon only owes Ruvain fifty zuz, Shimon need not swear. It is this power of the single witness in matters pertaining to an oath that the Gemara refers to, when it asks: Let us see from whom the seller took money.
It is for naught that רש"י said this awkward⁴See Tosfos there. According to Rashi we are forced to say that the Gemara is extending the reliability of the seller to even when he does not have possession of the garment. According to Tosfos, the Gemara is constantly maintaining that the seller is especially believed only when he has possession. Also, according to Rashi, we must amend the text. This is not necessary according to Tosfos. explanation. For here in Bava Metzia [the Gemara]’s question is sensible. For even if the sold article is not in the the seller’s possession, [the seller] should be believed as any single witness is. The Gemara’s question is: Why are both litigants required to swear? The one whom the seller corroborates should be exempt⁵See Tosfos there. According to Rashi we are forced to say that the Gemara is extending the reliability of the seller to even when he does not have possession of the garment. According to Tosfos, the Gemara is constantly maintaining that the seller is especially believed only when he has possession. Also, according to Rashi, we must amend the text. This is not necessary according to Tosfos. Tosfos here says as a matter of fact that when a single witness testifies in favor of one of the litigants, that litigant is exempt from swearing. This ruling does not enjoy universally agreement. See Rosh 3, in our Perek for a lengthy discussion of the pros and cons in this issue. from swearing and the other should be required to swear by Torah law? Now that we have explained that the Gemara’s question is that we should listen to the seller as a single witness, the text “ולא ידע - and he did not know”, is reasonable, for if [the seller] did know which customer he intended to sell the article to, he would be believed as a single witness insofar as swearing is concerned.
However, [the Gemara] could have answered⁶See מהרש"ל and מהר"ם who explain why this is true only according to Tosfos explanation, but not according to Rashi.
A) According to רש"י we believe the testimony of the seller. If the seller was not available, we would not allow the litigants to swear, because upon the seller’s return’ he may testify in favor of one of the litigants. Retroactively, we will see that the court’s ruling caused a false oath. The court will never issue a ruling where it could become obvious that one of the litigants swore falsely.
B) According to Tosfos, we do not especially believe the seller. He has the authority of any single witness to require an oath from one litigant by Torah law and to exempt his opponent. If we rule in his absence that both litigants must swear and he returns and testifies in favor of one of the litigants, we would still not have a situation where we know that there was a false oath, because we do not inherently believe the seller. He only has the authority to require an oath and to exempt from an oath. Even if the litigant whom the seller supports did swear, nothing happened. At the very most, he swore when he wasn’t really required to do so. As far as his opponent is concerned, we required him to swear and the seller also requires him to swear. There is no evidence that he took a false oath. the question by saying that the seller is no longer available to us, so that we might ask him. It is then that the Mishna rules: the garment is divided after both litigants swear.
Both Rashi’s and Tosfos’ explanation of the words: “Let us see from whom he accepted the money?” have legal ramifications, and our ruling will depend on the seller’s testimony. According to Rashi, the garment will be awarded to the customer that the seller supports. According to Tosfos, the customer whom the seller supports will not have to swear at all and his opponent will be required to swear by Torah law.
R’I suggests that the Gemara’s question is simply practical. Let us see what the litigants themselves have to say about the subject and perhaps we can settle the issue. The Gemara does not at all mean that the testimony of the seller is legally binding. R’I explains that the Gemara’s question is as follows: We should ask [the litigants] themselves from whom the seller accepted money. For we do not suspect them of lying about this, to say: I gave the money, when he did not give it at all. And [the litigants] are most probably also not arguing about who gave the money, but about to whom the seller consented to sell the garment. However, they are not arguing about who gave the money. We can therefore expect an honest answer. Once they agree that Ruvain gave the money, we will rule that the seller consented to sell it to Ruvain. Shimon who knows that Ruvain gave the money still believes that the seller wanted to sell the garment to him. We will rule that Shimon’s assumption is incorrect.

No, it is necessary - as he took money from both of them: We follow this version: "And we do not know from which one he was willing and from which one it was against his will." And we do not follow the version: "And he did not know." As even if he did know, the seller is not deemed credible once they have gone, as it was established there (Kiddushin 74a).

Our mishnah: That they are both told to swear, so one will swear falsely.

Let us say that our Mishna does not follow Ben Nanas.
We can say that [the Gemara] knew quite well that in our Mishna it is possible that both litigants picked it up simultaneously,¹What is compelling Tosfos to say that the Gemara was initially aware of the inherent difference between the case of Ben Nanas and the case of our Mishna? See אוצר מפרשי התלמוד.
A) Some say that Tosfos was looking at the Mishna dealing with the third hundred zuz, where all agree that the third hundred zuz cannot be divided because the division is definitely not true justice as Tosfos has explained earlier 2Ab ד'ה ויחלוקו. If our Mishna is also speaking of a case where the division cannot be true justice, we should rule that the garment is put away and held in abeyance. This forces us to say that in our Mishna it is possible that the garment belongs equally to both and the Gemara at this point was already aware of this.
B) Others say
C) A third opinion is that Tosfos felt that it is unlikely that the Gemara was unaware of this logical difference between the case of Ben Nanas where one of the litigants is intentionally swearing falsely and our Mishna where the litigants who are each swearing that they own not less than half may actually be swearing truthfully. whereas, in the case of the storekeeper whose records show that he paid the worker and he denies receiving payment, one is definitely lying and going to swear falsely, but even so the Gemara asks that the ruling in our Mishna should be that they divide the garment without swearing, since it is possible that one will come to swear falsely.²We must explain why the Gemara would even make such an assumption. Since Ben Nanas is so concerned about the courts ruling that leads one party to swear falsely, perhaps he holds that even if there is only a possibility of one of the parties swearing falsely, we must avoid swearing.
[The Gemara] answers that there in the Mishna concerning the storekeeper and the employee, there will definitely be a false oath. We may assume that Ben Nanas’ ruling is only for similar situation, not when there is only a possibility that one of the litigants may be swearing falsely.

Is not according to Ben Nannas: In Tractate Shevuot (45a), concerning a storekeeper [relying] on his ledger, these and those come to the court in order to make an oath, one of them in vain: A homeowner says to a storekeeper, "Give my son a dinar of wheat and I will have to pay"; or "Give my laborers a sela in small coins, which I am obligated [to pay them] for their wages, and I will have to give [you] a sela." And [later the storekeeper] says, "I gave it"; but [the laborer] says, "I did not receive it." So they both make a claim against the homeowner. Both of them take an oath and take [the money they are claiming] from the homeowner. Ben Nannas said, "How is it that both these and those come to take an oath in vain? Rather, they both take [the money] without an oath."

Say they lifted it together: About a lost object, each one holds, "I lifted it first and it is all mine." So when they swear about half of it, they are swearing truthfully. And also regarding buying and selling, perhaps [the seller] agreed to both of them.

In accordance with Sumakhos: In Bava Kamma (46a) concerning an ox that gores a cow and its fetus is found [dead] beside it.

The burden of proof rests upon him: With witnesses. But if not, he collects nothing. Whereas here, they divide [it] with an oath!

There, both are not in possession [of the disputed funds]. “There”, refers to the case in Bava kama 46a, where an ox gored a cow. A dead fetus was found next to the gored cow. The cow-owner claims the fetus died as a result to the goring and he is entitled to payment for the dead fetus. The ox owner maintains that the cow aborted the fetus before the goring and he need not pay. Sumchus rules that the disputed funds - the value of the fetus, are to be divided between the cow-owner and the ox-owner. Thus, the ox-owner pays only half. The Rabanan rule that the cow-owner can collect, only if he proves that the ox-owner is liable. In absence of such proof, he pays nothing.
At this point in the dialogue, the Gemara posits out that our Mishna which speaks of dividing the garment with an oath is logical according to the Rabanan who disagree with Sumchus. There, in Bava Kama 46a, we are speaking of a case where both are not in possession of the disputed funds.
A superficial understanding of the phrase “both are not in possession” indicates that neither the cow or ox-owner is in possession. This is of course not true. The ox-owner definitely is in possession of the disputed funds. Tosfos, therefore adds: only one is in possession of the disputed funds i.e. the ox-owner. It is the cow-owner who is attempting to extract the funds from the ox-owner. The Rabanan rule “the burden of proof is upon the one who attempts to extract funds from his associate”. In our Mishna where both are in possession of the disputed garment, it is to be divided.
In the particular case discussed in Bava Kama 46a, it is true that the ox-owner is in physical possession of the disputed funds. However, there is another case in Bava Metzia 100a, where neither has physical possession of the disputed property and even so the Rabanan rule that the plaintiff cannot extract payment from the defendant.
The Gemara on 100a: One who exchanges a cow for a donkey, and the cow calved. When the cow-owner takes possession of the donkey, ownership the cow is automatically transferred to the donkey owner. The cow need not be present. This creates a situation where it may not be known when the cow calved and to whom the calf belongs? The Mishna rules: the calf is divided between the two litigants.
The Gemara asks: Why should they divide the calf? Let us see in whose domain the calf presently is and [his opponent] will be in the position of one who is attempting to extract from his neighbor and the burden of proof is upon him?
The Gemara answers: Rav Chiya bar Abba says in the name of Shmuel: The Mishna is speaking of when [the cow] is standing in a meadow. It is in a place that belongs to neither of the litigants.
Once again the Gemara asks: Let us place ownership of the calf in the possession of the first owner, and the other litigant should be one who is attempting to extract from his neighbor and the burden of proof is upon him.
The Gemara answers: This Mishna is the opinion of Sumchus who says that money whose ownership is in doubt is divided without the litigants taking an oath.
We see from this Gemara that according to the Rabanan we would rule in favor of the cow-owner even if he is only the previous owner and not only when he is in physical possession of the calf. Even though when the calf is standing in a meadow and not in either of the litigants’ domain, the Rabanan hold that - the donkey owner is one who is attempting to extract the calf from [the cow-owner] and the burden of proof is upon him. Neither litigant has possession of the disputed calf. The Gemara says that according to the Rabanan this is a case of - extracting funds from a defendant, which can be done only with proof. How can Tosfos say that we rule in favor of the defendant only when he has possession?
Tosfos will now conclude that ‘possession’ need not necessarily be physical possession for one to be considered a defendant. It can also be possession in a legal sense. Even so, one is called in possession, because he was the previous owner. The cow-owner at one time was definitely the owner of the calf when it was a fetus. Our question is whether that status quo changed or not. The status quo is equal to being in possession. There are those whose text is “there, in the case of the ox goring a cow and we are in doubt about whether the calf dies as a result of the goring or not, the money in question clearly belongs to only one of them”, whereas in our Mishna where two litigants are each holding a garment they may both be owners of the garment.
According to this text, the difference between Sumchus’ case and our Mishna has nothing to do with who is in possession of the disputed funds. Rather, the reason the Rabanan rule in favor of the defendant and do not suggest division of the article is because the article or money in dispute definitely belongs to only one of the litigants. In our Mishna, where there is at least a possibility that they are equal owners, dividing the garment is the more logical choice.

We follow this version: Granted, if you say [it is like] the Rabbis - there, where both of them are not grasping [it], the Rabbis say, etc.; here where both of them are grasping [it], they divide [it] with an oath. But if you say [it is like] Sumakhos - now, if there, where both of them are not grasping [it], they divide it without an oath; here, where both of them are grasping [it], is it not all the more so?

Both of them are grasping: So there is no claimant [to] remove it from his fellow here.

They divide it with an oath: Since it lacks collection, in that his fellow is grasping [it] - as this one is grasping all of it and that one is grasping all of it - the Rabbis do not establish [the law, such that] money may be extracted from its assumption of ownership with nothing, as we said there. [Hence] the Rabbis, who need a proof, would require them [to take] an oath.

Uncertain and uncertain: Like over there, as we learned, "The fetus was found next to it, and it is not known if it gave birth before it gored it, or if it gored it after it gave birth to it and the fetus did not die because of the goring, but rather on its own." And since each [side] is making an uncertain claim, an oath cannot be imposed on them.

Of Rabbah bar Rav Huna: In the chapter [entitled] HaShoel below (Bava Metzia 100a).

A financial association: A loss of money. For if this one pays unjustly, it will be a loss of money [for him]; and if we exempt him unjustly, it will come out that the [other] will be lacking the offspring of his cow.

[Sumchus said that money in doubt is divided without an oath] where there is a derara demamona. The Gemara is saying that Sumchus’ ruling that money whose ownership is in doubt is to be divided without the litigants taking an oath, is in effect only when there is a derara demamona, but not in the case of our Mishna, where the litigants are each holding the disputed garment. The case of our Mishna is not one of derara demamona. But what does derara demamona mean?
Rashi explains that the word ‘derara’ means a monetary loss. Since the rightful owner of the disputed funds will suffer a loss, we do not suspect his opponent of intentionally inflicting the loss upon him and there is no reason to require an oath. There is no conceivable rationalization for taking away that which is legitimately his. Whereas, in our Mishna, be it in the case of a found object or a sold object, there are possible rationalizations as the Gemara said earlier. Therefore, an oath is required before dividing the garment.
Tosfos disagrees with Rashi about the meaning of this term. Tosfos here and in Bav Basra 35b, does not mention Rashi’s explanation and does not say why he rejects it. This is open for speculation. See אוצר מפרשי התלמוד who offers the following reasons for disagreeing with Rashi’s explanation:
A) It would seem that if one party will definitely suffer a loss, it is all the more reason to require an oath before dividing, in order to prevent this loss from occurring.
B) The categorization of our Mishna as one where there is no loss is difficult. Certainly, according to the letter of the law, when one picks up a found object, it becomes his legal property and when one takes it from him, the finder is suffering a loss. Even though the Gemara earlier said that the thief might say “my associate is losing nothing”, that is merely the rationalization of the thief, but it is certainly not the truth. Why does the Gemara refer to this case as one where there is no loss?
Tosfos therefore offers a different explanation of the term derara demamona. The meaning of derara demamona is: that even without their claims, the court would be in doubt about who the rightful owner of the disputed property is. The situation per se compels us to ask: who is the owner of this property? For example: in the case of an ox that gored a cow (Bava Kama 46a) where we are in doubt about whether the fetus died as a result of the goring or not. Any observer of the story realizes that there is a legitimate doubt about whether the ox-owner is liable or not.
So too, in regard to one who exchanges a cow for a donkey and the cow calved. Any observer has a legitimate doubt about when the cow calved, thus, the ownership of the calf is in question. Since the doubt arose of itself, not as a result of their claims, logic dictates that they should divide the disputed property even without taking an oath, as opposed to our Mishna where the facts of the case do not point to a dispute at all. We would simply assume that the garment is jointly owned. Since it is because of their claims of individual ownership that we know there is a dispute, we require an oath so that the dishonest litigant will retract his claim. This is not needed in the cases where Sumchus rules that the disputed property is divided without anyone taking an oath, because the circumstances indicate the need for division of the property that is in doubt.

If there, where there is a financial association, etc.: You cause a loss of money to whichever of them loses the half unjustly.

If there, where there is a financial association -- and we can assume it [belongs] entirely to one [of them]. The Gemara compares the cases of Sumchus to our Mishna and argues that if in Sumchus’ cases¹A) Bava Kama 46a, where we are in doubt whether the fetus dies as a result of being gored by the ox or not.
B) Bava Metzia 100a, where we are in doubt if the cow calved before the donkey owner took possession or afterwards. no oath is required, then certainly in our Mishna an oath should not be required. The Gemara offers two characteristics in which Sumchus’ cases differ from our Mishna:
A) In Sumchus’ cases there is a derara demamona, whereas in our Mishna there is no derara demamona. (See previous Tosfos for explanation of derara demamona.)
B) In Sumchus’ cases the disputed funds definitely belong to only one of the litigants, whereas in our Mishna the disputed property may be jointly owned.
These two characteristics are offered as reasons why it is more likely that one should not have to swear in our Mishna. Tosfos here is focusing on the second characteristic B), that in Sumchus’ cases the money belongs to only one of the litigants and even so no oath is required. Hence, in our Mishna where the disputed funds may actually belong to both, there should be no need for an oath.
We can garner from the Gemara that when the property definitely belongs to only one of the litigants, it is all the more reason to require an oath. Tosfos must explain that this view is not shared by all. In terms of protecting the rights of the one owner who is definitely absorbing a loss, it is true that it is more logical to require an oath in Sumchus’ cases than in our Mishna, where it is conceivable that neither is suffering a loss. However, if avoiding a false oath is of utmost importance, then in Sumchus’ cases there is a greater reason not to swear, because one of the litigants will definitely be swearing falsely. However, as the Gemara concluded earlier, in our Mishna there will not definitely be a false oath, which is more reason to require an oath.

Protecting a loss
Sumchus’ cases:^*The property definitely belongs to only one of the litigants. more reason to swear
Our Mishna:^**The property may be jointly owned. less reason to swear
Avoiding false oath
Sumchus’ cases:^*The property definitely belongs to only one of the litigants. less reason to swear
Our Mishna:^**The property may be jointly owned. more reason to swear

[The Gemara’s] question that there is a greater reason to exempt one from swearing in our Mishna is only if Sumchus subscribes to the opinion of the Rabanan who disagree with Ben Nanas, who are not concerned about the possibility of a false oath. If so, in Sumchus’ cases where one of the litigants is definitely suffering a loss, there is more reason to require an oath to protect the interest of the losing litigant, than in our Mishna where it is possible that neither of the litigants is suffering a loss.
But according to Ben Nanas who is concerned about the possibility of a false oath, to the contrary, when it can be said that the disputed property belong entirely to one of the litigants, they would divide the disputed property without an oath, because if both litigants swore there would definitely be a false oath. This is an important reason to avoid an oath in Sumchus’ cases, whereas in our Mishna where there is a possibility that there is no false oath, there is greater reason to require an oath.

If there, where there is a financial association. Our Gemara can be divided into two steps:
Step 1) The Gemara first distinguishes between Sumchus’ cases and our Mishna by saying that in each of Sumchus’ cases there is a derara demamona, whereas in our Mishna there is not.
Step 2) The Gemara then asks that it is more logical that in a case where there is no derara demamona such as in our Mishna, there should be no need for an oath.
This is the simplest way of understanding our Gemara. Tosfos will now introduce a Gemara in Bava Basra 35a, where we will see that this simple understanding of our Gemara is untenable. Bava Basra 34b & 356a: That ship that two litigants were arguing about. This one said it is mine and that one said it is mine. Rav Nachman said: Whoever is stronger will overpower his opponent.
On 35a the Gemara asks: Why is this different than what we learned in a Mishna: Concerning one who exchanged a cow for a donkey and the cow calved. So too, one who sold his maidservant and she gave birth. [The seller] says she gave birth before I sold her and the calf or newborn slave is mine. [The buyer] says: She gave birth after I purchased [the cow or mother], and the calf or newborn slave is mine - they are to divide the calf or the newborn slave.
The Gemara answers: There in the case of exchanging a cow for a donkey, [the seller] has some connection to the money in question and [the buyer] has some connection to the money in question. We therefore rule that it is to be divided. Here, in the case of the ship, if it is this one’s it is not that one’s. If it is that one’s it is not this one’s.
Ultimately the Gemara is saying that in the case of exchanging the cow for the donkey, there is a derara demamona and in the case of the disputed ship there is no derara demamona.
In Bava Basra 35a the Gemara rules in the case of a ship whose ownership was in dispute that the litigants struggle with each other and the stronger party wins. There as well the Gemara asks: Why is this different than the case of one who exchanged a donkey for a cow and it is not known when the cow calved, where Sumchus ruled that the disputed money is divided between the litigants? The Gemara answers there as it does here (step 1): In Sumchus’ case there is a derara demamona, whereas in the case of the disputed ship there is no derara demamona.
The Gemara there does not proceed to step 2 of our Gemara to ask that in the case of the ship we should also apply Sumchus’ ruling. Tosfos needs to explain why step 2 is not pursued in Bava Basra 35a. We are compelled to say that the question our Gemara asked in step 2 is irrelevant to the Gemara in Bava Basra 35a. Why?
In Perek Chezkas HaBatim (Bava Basra 35a) in regard to a ship whose ownership was disputed, where Rav Nachman said: The litigants will battle over it and whoever is stronger will overpower his opponent. The Gemara asks: Why is this different than one who exchanges a cow for a donkey where we rule that the calf is divided between the litigants? The same should be true of those disputing the ownership of the boat.
[The Gemara] answers: There when one exchanges a cow for a donkey or sells his maidservant, there is a derara demamona. Whereas, in the case of the disputed ship, there is no derara demamona. This of course is step 1 of our Gemara. The Gemara accepts this answer as a logical difference between Sumchus’ case of exchanging a cow for a donkey and the case of the ship. [The Gemara] there does not ask as it does here in step 2: How come there in the case of exchanging a cow etc. where there is a derara demamona and it can be said that it definitely belongs entirely to only one of [the litigants] and even so, they divide the calf or the newborn slave, whereas, in regard to the ship where it can be said that it truly belongs to both [litigants] and even so, they do not divide it, rather, we rule that whoever is stronger will overpower his opponent, and will take all, as the Gemara asks here on 3a in step 2. Our Gemara argues that Sumchus’ ruling should also apply to the case of our Mishna where two litigants are holding a garment, and we should divide the garment without the litigants taking an oath, but the Gemara in Bava Basra 35b does not ask that Sumchus’ ruling should be in effect in the case of the disputed ship. Why?
We must examine the thrust of the Gemara’s question in step 2 of our Gemara. Our Gemara feels that just as in Sumchus’ case the disputed property should be divided without anyone swearing, so too in our Mishna the garment should be divided without anyone taking an oath. It is in reference to the obligation of taking an oath that the Gemara argued: if in Sumchus’ case an oath is uncalled for, it certainly should not be needed in our Mishna of two who are holding a garment.
The Gemara there in Bava Basra 35a is discussing not whether one should swear in the case of the disputed ship, but whether it should be divided or settled through the decision of allowing the litigants to do battle and the stronger party overpowering the weaker party. The answer to that question is that when exchanging a cow for a donkey, a division is in order because there is a derara demamona. In the case of the disputed ship there is no derarra demamona and a division is uncalled for.
Tosfos explains that the derara demamona is only relevant to ruling that the object in question should be divided, but not to exempting the litigants from swearing. This is because as far as dividing the disputed property as in the case of the calf or the maidservant is concerned, the logic of derara demamona is an excellent reason to divide the disputed property, since it is an absolute doubt even without their claims, therefore logic dictates that the disputed property should be divided, but concerning the disputed ship, even though it is possible that it belongs to both litigants, since there is no derara demamona, and they are not in possession of the ship, the rule is - whoever is stronger will overpower his opponent - and he wins the ship.
The logic of derara demamona is used in Bava Basra to explain why the calf or the newborn slave is divided as opposed to the ship which is not divided because there is no derara demamona.
However, insofar as taking an oath is concerned, the logic of derara demamona does not dictate that the division be without an oath, since [the disputed property] definitely belongs to only one of [the litigants], logic dictates that it should be divided with the litigants swearing, so perhaps one of [the litigants] might confess that the disputed property is not his.
In step 2 our Gemara needs to explain why an oath is uncalled for in Sumchus’ cases, but is in order in our Mishna. The Gemara’s question is not based¹See מהרש"א and מהר"ם who raise a very obvious difficulty with Tosfos’ explanation that the strength of the Gemara’s question is not from the derara demamona aspect, but from the difference between the two cases that in our Mishna it is possible that the division is true justice, whereas, in Sumchus’ case it is definitely untrue, since the calf or newborn slave belongs to only one of the litigants. However, the Gemara when introducing its question does point out that in Sumchus’ case there is a derara demamona and in our Mishna there is not. On face value it seems that the Gemara’s question is based on this difference between the two cases. See מהרש"א who explains that the Gemara is not asking its question because of the derara demamona difference between the two cases. The question is based on the aspect of our Mishna being a situation where the division can be true justice and Sumchus’ cases where the division is definitely not true justice. The Gemara simply mentions the derara demamona aspect because the Gemara previously used this as an explanation of the difference between Sumchus’ cases and our Mishna. on the fact that there is a derara demamona in Sumchus’ case, but not in our Mishna. The derara demamona does not in any way say that there should be no oath. It is only a reason for division per se, but that division may be with or without an oath. The Gemara’s question that if an oath is not required in Sumchus’ case, it should certainly not be required in our Mishna, is based of the distinction between Sumchus’ cases versus our Mishna in that in Sumchus’ cases the disputed property definitely belongs to only one of the litigants and even so an oath is not needed. If so, certainly in our Mishna, where it is possible that the disputed property is jointly owned, there should be no need for an oath.
The Gemara in Bava Basra is not discussing the requirement an oath. It is only discussing division of the disputed property versus battling over it. The answer to that question is that where there is a derara demamona division is in order and where there is no derara demamona a division is uncalled for and we settle the matter by having the litigants battle over the ship.
According to Tosfos’ conclusion the point we made in our introduction about Step 2) must be modified. The Gemara’s argument that it is more logical that in our Mishna there should be no need for an oath because there is no derara demamona is untrue. The Gemara’s argument is that there is less need for an oath in our Mishna because of the possibility that the division may be true as opposed to Sumchus’ case where one party is definitely losing.