Can one tell a two year old child to turn on the heat on Shabbos for the baby, when it is very cold in the house? (The heat is needed for a baby, not for the two year old)
Answer:
It is not permitted to instruct the child to turn on the heater, which involves a Torah prohibition (according to the majority of rishonim and poskim, telling the child to perform the melachah for you is considered a Torah prohibition of shevisas beno (see Mechilta on Yisro, 20:10; Rashi and Ramban; Yerei’im 101; Chinuch 32; Rashba, Shabbos 153; Maggid Mishnah, Shabbos 20:7; and see many acharonim, including Mishnah Berurah, Shaar Hatzion 334:54; but see also Biur Halachah 266:6 concerning a child that does something from his own volition, though the Mishnah Berurah clearly writes that when a parent instructs him there is a Torah prohibition).
Although if the child does something for his parents of his own volition, the prohibition will not apply to a young infant who doesn’t understand that he’s doing it for his parents, a direct instruction will be forbidden. But, the child (a two year old) can be placed next to the heater, in the hope that he will play with it and turn it on, and this will not involve any prohibition (neither shevisas beno, nor safinan — both of which are present for instructing a child).
Of course, if there is actual danger, the heater can be turned on by an adult, and a shinuy (irregular means of turning on) can also be employed.
