By the Bais Hora'ah
I opened the windows and did not notice that my friend’s speakers were on the windowsill. The wind blew the curtains, which knocked down the speakers, and they broke.
Q: Am I obligated to pay for the speakers?
A: Last week we addressed the question of liability when the wind caused damage to the speakers. We differentiated between the wind knocking the speakers down directly upon opening the window and a situation where there was a lapse of time between opening the window and the wind blowing down the speakers. In the former case the one who opened the window is liable since it is considered as though he damaged the speakers directly. In the latter case he is exempt because the damage is indirect (grama).
This week we will discuss whether one is liable if the wind blew into the curtain, which then knocked over the speakers.
One of the four general categories of damages is esh — fire. One of the defining characteristics of esh is that there is another force that propels it to result in damage — the wind. The Gemara states that a person is liable if he places on a roof an object that is subsequently blown off by an ordinary wind and it damages an object below (C.M. 418:1). Since the wind propelled the object off the roof, the damage is categorized as esh. Regarding the category of esh, it is not even necessary to own the object that damages, because one is liable for damage caused by fire even if he does not own the fire. One who creates a fire that damages is liable regardless of ownership (Tosafos, B.K. 3b, d.h. U’mamoncha).
Consider the following application of this halachah, which shares a number of similarities to your case: While wind is blowing through an open window, someone hangs a curtain in front of the window. The wind blows into the curtain, which then knocks down and breaks an object. The one who hung the curtain is liable, regardless of whether he owns the curtain. Since he placed an object in a place where another force could propel it, he caused esh-type damage and is liable (Rema 390:5).
However, your case is fundamentally different. In your case you did not create the “fire.” The curtains were already in place and were not in a state in which they would cause damage. Opening the window allowed the wind to blow into the curtains and cause damage to items resting nearby. Since the damage resulted indirectly from opening the window, it is thus not categorized as esh (see Pischei Choshen, Nezikin 9:, which expresses uncertainty about the matter).
However, this exemption depends on who owns the curtains. If the one who opens the window owns the curtains as well, as in your case, he must consider whether it is likely that his object will damage someone else’s property. If that is the case, he owns the esh and is therefore liable even though he did not “ignite the fire” (Chazon Ish, B.K. 2:4; Mishpat Hamazik 2:45).
To summarize: When the damage occurs immediately, one is liable. If the damage does not occur immediately and results from the wind or a curtain that he does not own, he is exempt. If he owns the curtain, he is liable even if the damage is indirect. In all cases, if he was negligent he has a moral obligation to pay the owner.