If a person normally disengages his refrigerator light before Shabbat, but on one Friday night he cannot remember whether he had disengaged the light, may be open the refrigerator door, or is this forbidden, given the possibility that this might activate the light?
Rabbi Moshe Halevi (Israel, 1961-2001), in his work Menuhat Ahaba, rules that it is permissible to open the refrigerator door in such a case. He explains that in this situation, the individual does not intend to activate the light; his intention is merely to open the door. And since it is not certain that opening the door will activate the light, this situation does not qualify as a case of "Pesik Resheh" performing an action which will inevitably result in a Melacha (an action forbidden on Shabbat). Many Rishonim (Medieval Halachic scholars), including the Ramban, Rashba, Meiri and Ran, maintain that one may perform an act that might result in a Melacha, so long as this result is not definite and the person does not intend to achieve that result. Therefore, one may open the refrigerator door if he is uncertain whether the light is disengaged.
Of course, if he opens the door and the light turns on, he may not close the refrigerator door, as this will cause the light to turn off. He may ask a gentile or a minor to close the door, but may not do so himself.
If one knows for certain that he had not disengaged the light, and the light will thus certainly be turned on if he opens the door, then he may not open the door. He may, however, ask a gentile to open the door. Even though Halacha forbids asking a gentile to perform Melacha on ones behalf on Shabbat, one may ask a gentile to close the door in this case because he does not ask the gentile to perform a Melacha; his request is only that the door be shut. The fact that this will result in the lights activation is immaterial, since the request addresses specifically the opening of the door, and not the Melacha of turning on the light. As mentioned, however, one may not open the door himself in this case.
Summary: If one is uncertain whether or not he disengaged the refrigerator light before Shabbat, he may open the door on Shabbat. If the light turns on, he must ask a gentile or minor to close the door; he may not do so himself. If one knows for certain that the refrigerator light will turn on if he opens the door, then he may not open the door on Shabbat, but he may ask a gentile to open the door for him.
