The Tosphot in the beginning of Bava Batra seems to me hard to understand. The Mishna says partners that have decided to split up a courtyard are forced to build a wall. If it falls, it is therefore of both of them. Tosphot asks even without that reason it ought to be of both since we would not say המוציא מחבירו עליו הראיה (One who wants to claim money that is in the domain of his friend must bring a proof). In that case. The reason we would not say that is because it was not clear from the beginning that it belonged to just one. The question I have on this is that in the beginning of Bava Metzia we do say המוציא מחבירו עליו הראיה (his must bring a proof) in the case of a מציאה a found object.[My question here is that the lost object was not clearly of just one and not the other. And yet the Gemara still wants to apply the principle of המוציא מחבירו עליו הראיה
To me it seems there is a more simple explanation of our Mishna in Bava Batara. It is this. In our Mishna we say we split the wall and the Gemara says that is the case even if it has fallen into the domain of one of the partners. The Mishna in Bava Metzia says הממע''ה (his must bring a proof). What is the difference? Answer: in the Mishna in Bava Batra they are both forced to build the wall.
The same thing applies in a case where they were not forced to build it but had agreed to build it. In any case there is an original assumption that it belongs to both and that is why we do not say it belongs to just one even if it is in his domain.
The answer to this I think is that the Mishna in Bava Metzia does not actually say המע''ה. The Gemara applies it there but it is not openly in the Mishna. In fact the Gemara holds that Mishna can be of סומכוס (Sumhos) also.
[In any case it is obvious that the Ri [Rabainu Isaac] must have felt this question on the was so great as to be forced to say something in answer that is clearly not the great kind of answer. He must have felt the question on the mishna to be really powerful to force him into a corner. Even with my answer for the Ri I have trouble seeing the force of the question.] In any case it is clear to me that I need to do a lot more thinking into this to understand exactly why the Ri thinks this is such big question.
[I do not have a Gemara Bava Metzia to look this up]
I think you have to say that the Ri is simply using common sense. Just because the wall has fallen into the domain of one of the partners, why should that give him more claim to it than the partner?
To me it seems there is a more simple explanation of our Mishna in Bava Batara. It is this. In our Mishna we say we split the wall and the Gemara says that is the case even if it has fallen into the domain of one of the partners. The Mishna in Bava Metzia says הממע''ה (his must bring a proof). What is the difference? Answer: in the Mishna in Bava Batra they are both forced to build the wall.
The same thing applies in a case where they were not forced to build it but had agreed to build it. In any case there is an original assumption that it belongs to both and that is why we do not say it belongs to just one even if it is in his domain.
The answer to this I think is that the Mishna in Bava Metzia does not actually say המע''ה. The Gemara applies it there but it is not openly in the Mishna. In fact the Gemara holds that Mishna can be of סומכוס (Sumhos) also.
[In any case it is obvious that the Ri [Rabainu Isaac] must have felt this question on the was so great as to be forced to say something in answer that is clearly not the great kind of answer. He must have felt the question on the mishna to be really powerful to force him into a corner. Even with my answer for the Ri I have trouble seeing the force of the question.] In any case it is clear to me that I need to do a lot more thinking into this to understand exactly why the Ri thinks this is such big question.
[I do not have a Gemara Bava Metzia to look this up]
I think you have to say that the Ri is simply using common sense. Just because the wall has fallen into the domain of one of the partners, why should that give him more claim to it than the partner?
