We are continuing in siman 6, discussing the case of closing a box where there might be flies in the box that get trapped inside when it is closed. We learned that the Chayei Adam is looking at this case from the vantage point of psik reisha.
Rav Akiva Eiger asks that the case of the Chayei Adam is based on the Rema. The Shulchan Aruch brings this question and writes that it could be it is not considered tzad at all, because even after trapping them, they are still not accessible. The only way to get them is to open the box, and since they can then fly away, he never completes the process of trapping, which according to this opinion means trapping and acquiring control over the animal. He never acquires the control. The second opinion looks at the trapping aspect as enough to be assur. The Chayei Adam paskens in accordance with the second opinion by writing that one should shoo away any visible flies (which according to the first opinion is unnecessary), but one does not need to be concerned about the possibility of other flies that cannot be seen.
Rav Akiva Eiger points out that this psak does not seem to fit with the Rema in Yoreh Deah regarding stoking the coals under basar b’chalav, where the Rema paskens that one cannot stoke the coals, because one must be concerned for the possibility of basar b’chalav that they cannot see. It would seem to be a machlokes between the Shulchan Aruch here and the Rema in Yoreh Deah.
The Biur Halacha explains that even according to the opinion of the Rema in Yoreh Deah, that it is considered a psik reisha (or psik reisha l’she’avar), it is still a safeik. Therefore, since this case of tzad is a derabanan (because it is ain b’mino nitzad and a melacha she’ein tzircha legufa), one can be meikil. The case of the Rema is a safeik deoraysa, so even though it is a safeik psik reisha, one must still be machmir.
This discussion has tremendous practical applications. For example, if one wishes to open a refrigerator, there is a concern that the warm air from the kitchen will enter the refrigerator and cause the condenser to turn on. Similarly, if one opens an oven, there is a concern the cold air from the kitchen will cause the fire to turn on. The Gemara in Sanhedrin says that the first flow of air which would enter the appliance would be considered a person’s actions, and subsequent air is considered grama. If so, if the temperature inside the oven or refrigerator is close enough to the trip point of the appliance such that the first flow of air which enters the appliance will activate the appliance, opening the appliance door is a direct action on behalf of the person and is assur. However, the person opening the door has no idea what the temperature is inside the oven, making this case parallel to the case of basar b’chalav. If we consider this case as davar she’eino miskavein, it would be muttar. If we consider it a psik reisha, it will be a safeik issur, and if it is derabanan, one could be meikil, but if it is deoraysa, it would be assur.
Another example would be a water fountain. Depending on the current temperature of the water reservoir, the first flow of warmer water to enter the machine (to replace the water that leaves when the fountain is opened) might trigger the condenser, or might not trigger it.
It appears that the way to pasken these questions would depend on whether one follows the Shulchan Aruch and treats all of these cases as a davar she’eino miskavein (and therefore it would be muttar) or the Rema, and it would depend whether one treats these cases as a safeik psik reisha (and it would depend on whether the issur is deoraysa or derabanan). One should ask their rav for practical guidance.
Summary
It is a machlokes Shulchan Aruch and Rema whether cases akin to flies which might be trapped in a box are treated as a davar she’eino miskavein, and always muttar, or are treated as a safeik psik reisha, and it will depend whether the safeik is deoraysa or derabanan. One should speak to their rav for practical guidance.
