What is considered premeditated work on Shabbos?

What is considered premeditated work on Shabbos?

“Meleches machsheves asrah Torah” (The Torah forbids thoughtful work performed on Shabbos) is one of the basic precepts of the thirty-nine melachos (types of work forbidden on Shabbos): only if the act deliberately violates a melachah, it is prohibited. However, if the melachah is breached by an activity that is done for a purpose that is permitted on Shabbos, and the melachah itself is not an intended outcome, it‘s considered eino miskaven (unintentional) and therefore mutar(permitted). For example, the first of the thirty-nine melachos forbids furrowing the ground in preparation for planting. However, it is mutar to drag a lightweight bench or chair across the ground on Shabbos even if it may possibly create grooves—such furrowing would be considered eino miskaven.

A Bill on Beheading Chickens

An exception to the rule of eino miskaven is psik reisha (inevitability). The Gemara asks, “Psik reisha v’lo yamus?”  (Can a [chicken’s] head be severed and it doesn’t die?). Regarding melachos on Shabbos (and other prohibited acts), a person may say that they are merely decapitating the chicken with no intention of causing death—but death is, of course, inevitable; the act, although not premeditated, is considered intentional. In contrast to the light chair being dragged across the ground, as cited above, dragging very heavy furniture across the ground on Shabbos—which is certain to create furrows—is considered psik reisha, and therefore assur (forbidden).

A Doubt on Decapitation

An act that would be considered psik reisha if all the facts were known beforehand may be categorized as safek psik reisha (a doubt regarding inevitability—the uncertainty lies in the missing information). In such a case, poskim do not consider the outcome eino miskaven (which would be mutar, as stated previously). For example, the Rama (primary commentary on the Shulchan Aruch) says that a Jew may not stoke the coals of a non-Jew’s stove while food is cooking there (on a weekday—stoking coals is always forbidden on Shabbos). The stoker is not intending to cook the non-Jew’s food and also doesn’t know what’s in the pot—it may contain basar b’cholov (milk with meat) or it may be innocuous. But these combined circumstances—aiding the cooking process (even without clear intent) that may include forbidden food— is a safek psik reisha and therefore assur.

In terms of safek psik reisha, however, a distinction is made between an issur d’oraisa (a Torah prohibition) and an issur d’Rabbanan (a Rabbinic decree). Safek d’rabbanan lehakel (a doubt concerning a Rabbinic decree is ruled leniently), so regarding a d’rabbanan on Shabbos, safek psik reisha is mutar, according to many opinions. A classic example of a safek psik reisha on Shabbos is closing a small box or drawer that may or may not have flies in it. Trapping flies is assur, but since flies are a species not commonly trapped for use (ein b’mino nitzod), it is only a possible issur d’rabbanan, and would therefore be permitted on Shabbos. (Another reason that is brought for permitting this practice: once the drawer or box is opened, the flies immediately escape, so they are not considered “trapped” at all. For both these reasons together, closing the box or drawer would be permitted.)

Short Shrift for a Fridge?

A refrigerator* has a light that automatically engages when the door is opened. The Jewish fridge owner normally disables the light before Shabbos, but they are unsure if they remembered to do so on a short Friday afternoon. May the fridge be opened on Shabbos? The act of turning on the light by opening the door is psik reisha and the melachah (closing the electric circuit by engaging the light switch or magnet) is an issur d’oraisa. Opening the fridge door in this case is safek psik reisha and therefore assur.

 The solution would be to have a non-Jew open the fridge. Amirah l’nochri (asking a non-Jew to perform a melachah on Shabbos) is permitted in this case, because the rules of psik reisha (or safek psik reisha) do not apply if a non-Jew is acting in the owner’s stead. The instruction to the non-Jew to open the refrigerator is the only intent that counts and the inevitable— or possibly inevitable—outcome of the fridge light going on is not considered a melachah done on behalf of the owner.

*For a comprehensive summary of refrigerator use on Shabbos (as well as more on the subject of safek psik reisha) see Halachah #700. For more on amirah l’nochri, see Halachah #747 on plumbing issues; Halachah #692 on Shabbos shipping; Halachah #524 & Halachah #321 on cruises and hotels; Halachah #502 & Halachah #442 for the wheelchair-bound; Halachah #454 on community matters; Halachah #1 on the general principle.


Practical Halacha: One minute a day. By Horav Yosef Yeshaya Braun, shlita, Mara D'asra and member of the Badatz of Crown Heights.