Q&A: Light Bulb with a Motion Sensor
Light Bulb with a Motion Sensor
Question
Hello Rabbi, I was staying with friends this Sabbath. In their neighbors’ yard there is a light that turns on when it detects movement nearby. The problem is that it also turns on when people walk through the adjacent yard (where I was staying). The question is: is it permitted to walk there when I know it will turn on? By the way, I don’t benefit from it turning on; its light has almost no effect on my yard.
Answer
In my opinion it is permitted (although one could certainly analyze this in terms of the laws of an unwitting act and an inevitable result, especially since here it is an inevitable result involving a rabbinic prohibition, and there are authorities who permit this—the Magen Avraham and Terumat HaDeshen—but this is not the place to go into it at length). I seem to recall that Rabbi Wosner has a responsum about motion sensors, and if I remember correctly he permits it. My own straightforward reasoning to permit it, even aside from the laws of an unwitting act and an inevitable result, is something like: a person cannot prohibit something that is not his. It cannot be that someone puts something in his yard and thereby prevents me from using my own yard. True, this is more a reasoning from the laws governing neighbors than from the laws of the Sabbath, but it still seems correct to me. If we prohibit this, it would allow people to put such lights in the yards around me and box me in completely.
Discussion on Answer
I don’t know whether this is a joke at the expense of my reasoning or whether it was meant seriously, but the example isn’t comparable. The manufacturer caused you to stumble into a transgression, but once you bought it, it is indeed a transgression. And if you discovered sha’atnez there, demand your money back. What does that have to do with the case at hand?
And several halakhic decisors have already distinguished that when the prohibition inheres in the object itself, a person can prohibit something that is not his (for example, when someone mixed your meat with your milk). See my article in Midah Tovah, Parashat Chukat (it appears on the site).
Could this explain Rashba’s view regarding someone who locks his house and it turns out that a deer is trapped safely inside?
I assume you would limit the reasoning only to a case of indirect causation, where the one who installed the sensor and the sensor itself can be seen as performing the act, rather than the person walking nearby, and not to a case where my action is direct.
🙂 A joke, of course
Rashba explicitly writes: “Rather, if he intended to lock it also on its account, that is what he means—to say that if he needed to lock it on its account, it is permitted even though he intends that the deer be trapped inside it.”
You can see that this is not because the deer cannot force you to commit a transgression, because it is permitted even to intend to trap it.
“A person cannot prohibit something that is not his” doesn’t apply here. He did not impose a prohibition on something of yours. It’s simply that you are prohibited from performing labor, and if this is labor—then it is labor.
D,
I don’t see any connection to the deer. Can the deer cause me to commit a transgression? The deer is not a rational agent, so this reasoning doesn’t apply to it. And in any case, as is known, Rashba’s reasoning there has received several explanations among later authorities, and this is not the place to elaborate.
Daniel,
I wrote that it is something like the reasoning that a person cannot prohibit something that is not his. Obviously it is not exactly that.
It’s not clear to me what “something like” the reasoning that a person cannot prohibit, etc., means.
Either this act is labor/creating something new—and then it is prohibited.
Or this act is not labor/creating something new—and then it is permitted (and perhaps it is not labor because it is indirect causation/happens on its own + it is not beneficial to him).
It cannot be that this is labor and yet it would be permitted simply because otherwise people could put such lights in the yards around me and box me in completely. We have not found that labor becomes permitted because of the possibility of abuse by others.
Unless you mean to propose that this is a stronger level of “it is not beneficial to him,” or that this is not Torah-level labor, and the Sages did not decree in a case like this because it enables abuse—what would be the basis for that? It needs proof.
See here: https://drive.google.com/drive/folders/0BwJAdMjYRm7IY0xlc1dmYTMweVE
Lesson 40, Chukat
I already explained my view. I’ll just comment on your request for proof. If there is sound reasoning, proof is not required (“Why do I need a verse? It is logical”). And even if I were to bring proof from Rashba, would you ask him whether he has proof? So why is Rashba allowed to offer a line of reasoning and I am not? There are many such reasonings in Jewish law, and usually they arise from reasoning, not from proofs. That is why I referred you to my article on Parashat Chukat that was linked here. Especially since we are dealing with a rabbinic prohibition and I also added other considerations here (such as an inevitable result involving a rabbinic prohibition)
Following up on this question: you mentioned the reasoning that a person cannot prohibit something that is not his. What would the law be if I visit a secular friend on the Sabbath and at the entrance to his house there is an electronic eye (an LED that blinks when someone passes near it) and a flashlight that turns on automatically? Would it be permitted to visit the friend because this falls under that same leniency—that a person cannot prohibit something that is not his—or in this case, since it is a yard that belongs to the friend and he is also the owner of the light, does he prohibit passage near the light and the sensor for himself and for everyone else?
Indeed, that reasoning does not apply to a person’s own yard. But the other leniencies still apply.
Regarding the Rabbi’s brilliant reasoning, I usually extend it also to matters of Yoreh De’ah—for example sha’atnez. It cannot be that a clothing manufacturer who mixes linen with wool can force me to violate my will, just because I wear the garment