You arrive home after shul on Friday night. All the dishes washed before Shabbat are locked in the dishwasher. You have no other eating utensils and you want to retrieve them for the Friday night meal. In order to take them out you have to unlock the door by turning the lever lock to the left. The action of the lever to unlock the door automatically turns off the panel indicator lights that advise you the dishwashing cycle is complete. So you cannot open the door without turning off the lights. What do you do?
Clearly, the act of retrieving the dishes from the dishwasher is, in itself, a permissible act on Shabbat. The problem is that it inevitably causes the melachah of switching off the indicator lights. This melachah is the inevitable and unintended result of retrieving the dishes, though it is of no use to its performer. An inevitable melachah that is of no use to its performer and that arises out of a permitted act is known in halachic terminology as psik reishe de lo neecha leh. We shall refer to it as the “inevitable, unwanted melachah.”
If one performed an inevitable, unwanted melachah, one is patur, which means exempt from any biblical liability. The question is whether one is allowed under rabbinical law to deliberately perform an inevitable, unwanted melachah such as, for example, turning the indicator lights off in order to retrieve the dishes.
The answer to this question depends on the classification of the inevitable, unwanted melachah and the existence or absence of any mitigating circumstances. If the inevitable, unwanted melachah is biblically prohibited, then according to the majority of halachic opinions one may not deliberately perform the permitted act that causes it. There is a minority opinion – that of the Aruch – that permits it, but the halacha does not adopt this minority opinion.
Accordingly, one may not, for example, wash one’s hands over a public lawn because even though washing one’s hands is permitted on Shabbat, it causes the inevitable, unwanted result of watering the grass. And watering the grass on Shabbat is classified under the biblical melachah of plowing and sowing.
Similarly, one may not open a door to the street on a windy day when the inevitable, unwanted result of the permitted act will be that lighted candles placed next to the door blow out.
What if the inevitable, unwanted melachah is not biblically prohibited but only rabbinically prohibited? Still, according to the majority of opinions, one may not deliberately perform the permitted act that causes the rabbinical melachah, except in a limited number of mitigating circumstances. Physical pain or discomfort or the performance of a mitzvah are examples of mitigating circumstances that might permit one to deliberately perform the permitted act that causes the inevitable, unwanted rabbinical melachah.
For example, trapping a bird inside one’s home is rabbinically prohibited. Yet if a wild bird flew into one’s house in winter, one would be allowed to close the windows to avoid the cold. This act is permitted even though it causes the inevitable, unwanted rabbinical melachah of trapping.
If the red berries on the hadas, the myrtle branch, are more numerous than the myrtle leaves, the hadas is invalid for arba minim. Yet if a friend of the hadas owner picks off the berries on Yom Tov for food, the owner of the hadas would be permitted to use it for the mitzvah of arba minim. Picking the berries in this way is permitted even though it causes the inevitable, unwanted melachah of fixing something for use – makeh bepatish – because it enables the performance of a mitzvah.
Is the inevitable, unwanted melachah of turning off the dishwasher indicator lights a biblical melachah or a rabbinical melachah? The biblical melachah of extinguishing fire was performed in the Sanctuary to produce glowing embers needed to smelt metal. Extinguishing fire for any other purpose not used in the Sanctuary is called a melachah she’eina tzericha legufa. Although biblically exempt from liability once performed, a melachah she’eina tzericha legufa is rabbinically prohibited and should not be deliberately performed. The majority of modern poskim agree that turning off an electric light involves the act of extinguishing fire and is therefore prohibited under the category of melachah she’eina tericah legufa. It is further accepted that the rabbis are less lenient with the melachah of extinguishing fire than with other rabbinical melachot.