Bava Basra, Chapter 3, Mishnah 7. In the previous Mishnah, we discussed Reuven and Shimon who were neighbors, where Shimon had a private area that Reuven encroached upon. In our Mishnah, we are dealing with an area shared by both of them - a jointly owned courtyard - and the restrictions placed upon Reuven, so that he does not infringe upon Shimon's use of that space. The main discussion is about damage caused by being seen, meaning the infringement upon or restriction of a neighbor's privacy.
"Lo yiftach adam chalonosav lachatzar hashutafin" - A person may not open his windows into a shared courtyard:
Simply put, a person is not allowed to open a new window overlooking the shared courtyard. Reuven and Shimon are partners in one courtyard, and both their houses open into it. Shimon can argue: While you are allowed to be in the courtyard whenever you wish, I can know when you are there and when you are not, and when you are not there, I go about my private affairs without the feeling that an eye is watching me. However, if a window is opened overlooking the courtyard, I will never again know when you are looking at me, and I will never feel comfortable. This is damage caused by being seen and an invasion of privacy, and therefore it is Shimon's right to object to the opening of a new window overlooking the shared living area.
Buying a House in Another Courtyard:
We have another case: two adjacent courtyards belonging to two different groups of residents, courtyard A and courtyard B. Reuven is a partner in courtyard A with his other neighbors, and now he purchases a house in courtyard B. The front of the new house opens into courtyard B, but in the back wall, facing courtyard A, there is currently no opening. If he breaks a new opening in this wall, the residents of the house will be able to come and go through courtyard A as well.
Here the Mishnah establishes that Reuven's partners in the shared courtyard may object and argue: In practice, you are adding residents to our courtyard, since the inhabitants of the new house will enter and exit through the back opening and pass through our courtyard A. This is an invasion of our privacy and an unauthorized use of our property. Even though Reuven himself is one of the residents, and is allowed to use the courtyard as he pleases, he is not allowed to use his right to add a resident or increase foot traffic. And this is the language of the Mishnah: "Lakach bayis bechatzar acheres - lo yiftachenah lachatzar hashutafin" - one who buys a house in another adjacent courtyard may not open an entrance from it to the shared area, because by doing so he adds a resident to the courtyard.
Adding an Upper Story and an Entrance - The Approach of the Bartenura:
The next line in the Mishnah introduces a new matter, similar to the previous one: adding residents or entrances to a shared area. We will first learn according to the approach of the Bartenura, and afterwards we will see how the Rambam learns this. "Boneh aliyah al gabei beiso - lo yiftach pischah lachatzar hashutafin" - one who builds an upper story on top of his house may not say: I will settle an additional resident in it and build a new staircase opening into the courtyard below. This may not be done, since doing so creates additional entrances and increased foot traffic, and the other residents may object.
The Mishnah continues: "Ela im ratzah - boneh es hacheder lifnim mibeiso" - one who wishes to add living space may take his existing living space and divide it in two, such as dividing the living room into two rooms, and even rent out the new room to someone else. And similarly, "uboneh aliyah al gabei beiso" - he may add an upper story on the second floor of his house and even settle new residents there, as renters. However, "ufoschah lesoch beiso" - the entryway and exit for those residents must pass through his house, and a new entrance or exit to the shared courtyard may not be created.
It turns out, according to the Bartenura, that the neighbors cannot object to bringing a new resident into the house, since a person may bring as many people as he wants into his house, even paying renters who are not part of his family, provided that two conditions are met:
That the area of the house does not increase outwardly: In accordance with the opinion of the Rashbam, the external structure remains as it was, and the division is made only in the internal space, so that there is no encroachment upon the neighbors' area.
That no entrance is added: All foot traffic passes through the same door through which they have always entered the house.
When these two conditions are met, the neighbors have no right to object to the increase of residents in his house, since a person is allowed to bring as many individuals as he wants into his house, whether they are from his family or not from his family. This is how the Bartenura learned, and it aligns with the approach of the Rashbam.
The Approach of the Rambam:
Other commentators, primarily the Rambam, understood the Mishnah in a completely different way. In their view, a person is not allowed to add new residents to his house if they are not members of his household. If they "depend on his table," meaning his family members whom he supports, he is certainly permitted to do so - no one can tell a person how many children to bring into the world, or if his mother-in-law may move in with him. However, he is absolutely not allowed to bring an outside renter into his house. On the other hand, he is allowed to expand the area of his house or add an additional floor to it, since this does not come at the expense of one of the courtyard members, provided that no additional entrance is opened to the main courtyard. As long as the entrance remains as it was, and only the house grows, this is permitted.
It turns out that the words "u'voneh aliyah al gabei beiso" - and he builds a loft on top of his house, are interpreted in two ways: according to the Bartenura, the roof does not change at all, but rather they add a sort of attic within that same structure itself; whereas according to the Rambam, a person is actually allowed to add an additional floor. And the difference between them is that the Bartenura allows seating strangers there who are not family members, and the Rambam forbids it.
"Pesach keneged pesach v'chalon keneged chalon" - an entrance opposite an entrance and a window opposite a window:
The Mishnah continues: "Lo yiftach adam lachatzer hashutafin pesach keneged pesach v'chalon keneged chalon" - a person may not open into a partners' courtyard an entrance opposite an entrance and a window opposite a window. At the beginning of the Mishnah, we learned that Reuven is not allowed to open a window overlooking the shared courtyard, due to Shimon's claim that his privacy is compromised and he does not know when he is being watched. Now, even if Shimon gave his permission, and even if all ten residents of the courtyard agreed to it and told him to open a window - nevertheless, a person is not allowed to open a window or an entrance aligned exactly opposite his neighbor's window or entrance. For with every exit from the house, if the neighbor's door is open, he will see into his house, and with every look out the window, he will look into his window. This is forbidden, even with the agreement of the neighbors.
The foundation of this law is fundamentally different, and it relies on the story of Bilaam, who looked upon the dwelling place of the Jewish people in the wilderness and was amazed by the proper behavior, holiness, modesty, dignity, and humility of the Jewish homes - as everyone had their own privacy, because their windows were not aligned opposite one another. Therefore, even if the residents agreed, one must not create a window that looks directly into a neighbor's window, because it compromises human dignity and modesty. This is not merely a matter between man and his fellow, but rather like a matter between man and the Omnipresent - a level of holiness expected of the Jewish people. Keep this point in mind, and we will return to it shortly.
Expanding an Existing Entrance:
Furthermore, if someone has permission to open a window or an entrance - is he allowed to expand it? The answer is negative, since every additional expansion compromises the privacy of the other residents to that corresponding extent. Therefore, "hayah katan - lo yaaseh oso gadol" - if it was small, he may not make it large. Not only that, but even if he does not enlarge it at all physically, but rather divides an existing entrance into two doors, such as an entrance eight amos wide that is made into two doors of four amos side by side - this too is forbidden: "echad - lo yaaseh oso shenayim" - if it was one, he may not make it into two. The reason for this is that one entrance opening into the courtyard will mostly be closed, whereas when he has two entrances before him, it stands to reason that he will leave one of them open more frequently, and he ends up looking into the courtyard more than at first, diminishing the privacy of the courtyard members.
"Aval posei'ach hu lirshus harabbim" - but he may open into the public domain:
After all that was said, the Mishnah concludes: "Aval posei'ach hu lirshus harabbim pesach keneged pesach v'chalon keneged chalon" - but he may open into the public domain an entrance opposite an entrance and a window opposite a window. This applies if his neighbor lives across the street, and the street separating their houses is a public domain. The intention is not a public domain as defined in the laws of Shabbos - although the Rashbam holds this way, according to the Bartenura the intention is merely a public thoroughfare. If Reuven and Shimon live on opposite sides of the street, and Reuven wishes to open a new window exactly opposite Shimon's window - he is permitted to do so, because Reuven is no worse than any passerby. Every pedestrian walking in the street who turns to his right sees into Shimon's house, and Reuven will see just as they do, so Shimon loses nothing. This, of course, refers to the ground floor, and not to a second floor that is above four amos, into which pedestrians do not see.
For the same reason, the Mishnah continues: "Hayah katan - oseh oso gadol, v'echad - oseh oso shenayim" - if it was small, he may make it large, and if it was one, he may make it into two. One whose house faces the public domain is allowed to enlarge his entrance or open a larger window, for there is no privacy anyway for someone facing the public domain; and he is likewise allowed to make two entrances out of one, for that exact same reason.
In summary: In this Mishnah we learned the laws of privacy in a shared courtyard: the prohibition against opening a new window into a partners' courtyard due to the damage caused by sight; the prohibition against opening an entrance from a house bought in another courtyard into the shared courtyard, because it adds residents and foot traffic; the dispute between the Bartenura and the Rambam regarding adding a loft and bringing in residents who are not members of the household; the prohibition against opening an entrance opposite an entrance and a window opposite a window even with the neighbors' consent, which is based on the holiness of the Jewish homes that Bilaam testified about; the prohibition against expanding an existing entrance or making one into two; and the permission to do all these things toward the public domain, which inherently has no privacy to begin with.