1. Ma'aka and Tzitzis are in this week's parsha
2. a parenthetical observation (with pictures) about Orthodox Jews whose houses ought to have a ma'aka but who avoid building one.
3. issue: on Shabbos, or any time when doing these mitzvos would be impossible, can you live in a house without a ma'aka or wear a tallis without tzitzis or use keilim that you weren't tovel. i.e., does the impossibility of doing these mitzvos allow you to ignore them by considering the general obligation to be temporarily irrelevant.
4. machlokes rishonim, machlokes how to pasken.
5. the Netziv's explanation of what underlies the machlokes.
This week's parsha mentions two mitzvos several pesukim apart that seem to have nothing in common. The first is the Mitzva of Ma'aka, that requires that we place a fence around the roof of our houses,
(Before I get into the dvar torah, I want to mention briefly something that has always surprised me: In my neighborhood, there are some houses that have a ma'aka, such as this, which has a ma'aka twice the size necessary: (click on picture to enlarge)
(The standard Ma'aka is ten tefachim -Chazon Ish- no less than around thirty nine inches- high and strong enough to support a person leaning on it. For the Minchas Chinuch's kashe and the Emek Bracha's answer regarding different types of tefach in the shiur of ma'aka and shofar, see http://divreichaim.blogspot.com/2007/08/quality-vs-quantity-shiur-tefach-by.html)
On the other hand, many people who have houses that might require a ma'aka who do not have one. We're talking about houses that have what we call a veranda-- a flat roof that is accessible via a door from the second floor of the house. This is a classic example of the chiyuv de'oraysa of ma'aka. These people asked Rabbanim, and were told, as is the accepted halacha, that if you never use the roof, if you lock the door, then you are not chayav to build a maakah. I say that there is a difference between fulfilling the mitzvah and eliminating the obligation. But halachicly, they are correct.
What if you are given the opportunity to live in a house, and there is an accessible flat roof that requires a ma'aka, but you cannot put a ma'aka up; it is impossible for you to put it up. For example, you simply do not have the money or materials to do it; or there is some legal restrictions; or simply, you want to stay there only Shabbos when building is assur. Let's say that the circumstances are such that we would categorize this as Oneis; circumstances of absolute constraint, compulsion, or coercion. The halacha of Oneis is that we are not held responsible for oneis; annus, Rachmana patrei; one who is compelled is not held responsible. Theoretically, then, one would be allowed to move into this house, because he is an annus regarding his obligation to build a ma'aka, and an annus is free from liability.
The same question can be asked regarding tzitzis. What if you have a four-cornered garment that you would like to wear, but it is impossible for you to put tzitzis on it. Classic example: the tzitzis on your tallis become passul on Shabbos. Can you wear the tallis? Perhaps we can say that there is nothing wrong with wearing a four-cornered garment, but we are obligated to put tzitzis on it. But here, there is no obligation to do so, because you cannot possible put tzitzis on the garment on Shabbos, so you should be able to wear the tallis without tzitzis.
In fact, this question arises in innumerable applications. You can't drink or eat from a utensil that belonged to a gentile that is now owned by a Jew unless it was immersed in a Mikva. What if you are a guest at someone's house, and he is not religious, and he definitely was not toveil his keilim? Or what if you have a kli that you never used until Shabbos, and you want to use it on Shabbos. Since putting keilim in the mikva is prohibited on Shabbos, you are an annus. Can you use these keilim?
In all these cases, there is a fundamental argument against the application of the rule of Oneis, and that is that nobody is making you move into the house, or wear the serape, or drink from that cup. You may be an annus on the associated mitzva, but who asked you to willingly and without duress create circumstances that result in the application of the rule of Oneis? On the other hand, you are allowed to live in houses and wear garments and drink from cups; just that the Torah obligates you to do something additional when you do these things, or before you do these things. Here, the obligation is legally void because of the rule of Oneis, so you currently have no obligation at all. Or, to put it another way: you can't wear a garment without tzitzis because it is a bittul asei, a disregard of a mitzva obligation. Where you can't fulfill the mitzva, you cannot be said to have been mevateil the asei; you were unable to fulfill it.
The natural inclination at this point is to argue that ma'aka is different, because the Torah says "velo sasim damim be'veisecha," do not disregard this mitzva and put blood guilt on your house. But the fact is that Ma'aka is not a general safety rule; there is no requirement of ma'aka on a solid piece of concrete on your property that is very tall and has steps to the surface; ma'aka is only required where there is space under the surface for a dwelling. If so, it seems that the threshold issue is: Is there an obligation to put a ma'aka or isn't there. If there isn't, then my house is no different than that block of concrete which has no obligation at all. Also, see the Rambam mentioned toward the end regarding a bracha on making a ma'aka, which proves the same point.
The opinion of the Mordechai is that you may wear a tallis without tzitzis on Shabbos, based on the rule of Oneis. Theoretically, the same will apply to Ma'aka and tevilas keilim. The Mordechai is cited by the Beis Yosef and the Rama in OC 13 and the Magen Avraham there in SK 8, who says that the idea is also true in the cases of Mezuza and Ma'aka.
HOWEVER, see the Netziv here and in the addenda in the back of the sefer (unless you have the new edition in which, I think, the addenda have been incorporated into the body of the sefer.)
He says that the halacha lemaiseh is that if you can’t make a ma’aka, you can’t live in the house; if you can’t get a hold of a mezuza, you can’t live there; if you can’t make tzitzis, you can not put on the garment, and if you do, it's a bittul asei de'oraysa. (I don't know why he doesn't simply say, regarding Maakah, that you can live there, but you should not use the roof. Maybe he holds you need paratz es petzimav even by a maakah.)
The Mordechai et al hold that the obligation to put tzitzis into the garment only begins after you have put on the garment, and on Shabbos, it is assur to tie the knots that are essential to tzitzis, so you are pattur from the chiyuv of putting in the tzitzis, and you can continue wearing the beged (although there may be an issur d’rabanon, it wouldn’t apply where there is any degree of a kavod habri’os problem in not having the tallis on.)The Netziv says that “asher t’chaseh bah” shows that the chiyuv begins before you put on the beged, and so if there are no tzitzis in it, you cannot put the beged on in the first place, even on Shabbos. Whether the Netziv's reason to argue with the Mordechai applies to Ma'aka and tvilas keilim is debatable. You are welcome to think about it.
Speaking of Ma’akoh: I saw that the Lubavitcher in his Sichos here asks: the Rambam in Hilchos Brachos 11 says that we don’t make a bracha on things that are intended to prevent danger (like mayim achronim.) A few halachos later, the Rambam says that we make a bracha on making a ma’aka, which is an apparent contradiction, because the Torah says clearly that the mitzvah of ma'aka is to prevent accidents from happening/because of the danger! Obviously, there are a whole range of possible answers: difference between deoraysa and derabbanan; danger to self and danger to self and others; present danger and future danger. But the Lubavitcher then brings that the Rambam says in Sefer Hamitzvos that you don’t count a reason for a mitzvah as a separate mitzvah (e.g., lo yarbeh and lo yasur are not separate.)
How would the Rambam know this? Perhaps he's using the Gemorah in Sanhedrin 21a, and holds like R’ Shimon (doresh ta'ama di'kra), who says that an explicit reason means that the mitzvah is untied from the stated reason. But we don’t know if the Rambam holds like R’S or R’Y. Also, someone answers that the Rambam holds you have to put the Ma’aka up before using the house, even if you don’t plan to use the house, unlike mezuza, so there’s a separation between the lo sasim and the mitzvah.