A unit by Stanley Peerless

This is a unit that analyzes the application of the laws of Shabbat to a thermostat-controlled electric device such as the refrigerator. It is a good example of curriculum integration because it enhances both the study of halakha and the study of physics. It also demonstrates the way in which halakha relates to technological advances, an excellent example of integrated thinking.


As an introduction to this study, a review of the 39 Avot Melakha should be conducted, and the following concepts should be clarified:

1. Avot Melakha – The 39 categories of work that were done in the Mishkan. These are the categories that are forbidden by the Torah, based on the juxtaposition of the building of the Mishkan and the prohibition of work on Shabbat in Parashat Vayakhel.

2. Toladot – Work which is different from that done in the Mishkan, but which achieves the same result. These types of melakha are also prohibited by the Torah.

3. Rabbinic Decrees – There are a number of additional activities that are forbidden by the Rabbis. There are several categories of decrees that prohibit:

a. Activities that might lead directly to the violation of a Torah prohibition.

b. Use of items not designated for Shabbat use (muktzeh – lacking proper preparation).

c. Activities that might lead one to think that prohibited activity is permissible (marit ayin).

d. Activities that are not appropriate for Shabbat, even though they are technically permissible (uvda d’chol).

Students should also be introduced at this point to the physics of circuits and thermostats. They might be asked to identify melakhot that relate to the use of electrical appliances (i.e. igniting and extinguishing, building and destroying in relation to the circuit).


Teacher’s Guide to Texts

Text #1(Mishneh Torah of the Rambam, Hilkhot Shabbat 1:1-4): In this text, the Rambam establishes the consequences of violating the various prohibitions of Shabbat. One of the purposes of this study is to understand the Rabbinic terminology in this regard:

1) “chayav” – indicates the violation of a Torah prohibition.

2) “patur” – indicates the violation of a rabbinic prohibition, which although forbidden a priori (“assur”) nevertheless does not ex post facto carry the punishment associated with the Torah prohibition.

3) “assur” – forbidden a priori

4) “mutar” – completely permitted a priori


Text #2(Betzah 13b): This text establishes that only a “melekhet machshevet” is forbidden by the Torah. According to Rashi, “melekhet machshevet” is the work of a craftsman. It is work that is carried out in a considered and careful manner. There are seven conditions for a melakha to be considered a “melekhet machshevet”. Many of the texts that follow deal with those conditions. Note: the seven conditions of melekhet machshevet are that the action must be: 1) intentional, 2) performed in a normal way, 3) done completely by the person involved, 4) more than the minimum amount required to create culpability, 5) enduring, 6) direct, and 7) for the purpose that the action was done in the Mishkan. An action lacking any of these conditions would not be considered a Torah prohibition.


Text #3(Shabbat 22a): Texts 3-8 deal with the concept of “davar she’eino mikaven” – an unintended act. It is important to differentiate between accidental and unintentional. Accidental (“shogeg”) in halakha means that the person knew that he was performing the act, but that he either did not know that it was forbidden on Shabbat or he did not know that it was Shabbat. “Davar she’eino mitkaven” refers to an unintended secondary action that results from a permitted act that was done intentionally. This text introduces the concept of “davar she’eino mitkaven” and the fact that it is permissible a priori.


Text #4(Shabbat 29b) and Text #5 (Pesachim 25b-26): These texts discuss the application of “davar she’eino mitkaven” in situations where there is an alternative way of acting and in which there is no alternative. The gemara in Pesachim establishes that the essential argument between R. Shimon and R. Yehudah on “davar she’eino mitkaven” is that one emphasizes intention and one emphasizes whether there is an alternative course of action. Through this gemara, we can establish that we go according to the opinion of Ulah in text #4. Also, Tosafot adds that a very difficult alternative is not considered an alternative.


Text #6(Shabbat 120b): This text qualifies the law of “davar she’eino mitkaven” by adding that if the resulting action is inevitable (“psik reisha velo yamut”), it is forbidden.


Text #7(Zevachim 91b): Rashi’s commentary on the text reduces the concept of inevitability (“psik reisha velo yamut”) to situations in which the result is 100% inevitable. This means that if the act can be performed in a way that the resulting forbidden action does not necessarily occur, it is permissible to perform the act even in a manner that the resulting action will occur.


Text #8(Shabbat 103a): Tosafot, in the commentary on this Gemara, quotes the opinion of the Aruch that an inevitable result (“psik reisha velo yamut”) is only forbidden if it is beneficial (“nicha lei”). This concludes the section on “davar she’eino mitkaven.”


Students should be asked to relate the concept to the thermostat control. Is it a “davar she’eino mitkaven” ? Is the result inevitable? Is it beneficial? On the one hand, it seems to be a “davar she’eino mitkaven” that is inevitable and beneficial, which would make it forbidden. There are poskim, however, who explain that the fact the entry of warm air into the compartment of the refrigerator is not beneficial makes it “lo nicha lei.” A similar analysis should be done after studying each of the seven conditions of “melechet machshevet.”


Text #9(Shabbat 92a): The Mishnah establishes that a melakha that is done in an abnormal way is “patur aval assur. ”Rashi, based on a grammatical ambiguity (indefinite antecedent), brings two interpretations of the Mishnah – 1) normalcy is determined by society (relative) , 2) there is an absolute standard of normalcy.


Text #10(Shabbat 92a): The Gemara discusses whether the societal determination is based on local, national, or international standards.


Text #11 (Shabbat 92b) and Text #12 (Shabbat 93a): These two texts along with the next three deal with the partial performance of a melakha. Texts 11 and 12 establish that two people who do the work of one person are considered “patur aval assur.”


Text # 13 (Yoma 73b),Text #14 (Yoma 74a) and Text # 15 (Rambam, Hilkhot Svitat Assor 2:3): These texts discuss one who does less than the required amount of a prohibited act (“chatzi shiur”). According to R. Yochanan it is “patur” but “assur min haTorah” (forbidden according to the Torah, unlike most other similar situations in which the prohibition is Rabbinical). Resh Lakish disagrees, holding that it is a Rabbinical prohibition. The gemara explains that R. Yochanan’s position is based on the fact that he can always do another action that will connect to this action and as a result make him “chayav.” The Rambam establishes that we go according to R. Yochanan.


Text #16 (Shabbat 105b): Establishes that the performance of a melakha that is destructive is “patur aval assur.


Text #17 (Rambam, Hilkhot Shabbat 9:13): Establishes that a melakha that does not endure is “patur aval assur.


Text #18 (Shabbat 120b): Establishes that a melakha that is performed indirectly is “patur aval assur,” and in the case of significant loss would be permissible.


Text #19 (Shabbat 93b), Text #20 (Shabbat 94a), Text #21 (Mishna Shabbat 2:5), and Text #22 (Shabbat 31b): These texts deal with an action that is similar to the melakha that was done in the Mishkan, but is done for a different purpose. For example, trapping an animal in order to protect people rather than for using the animal is considered a “melakha she’eino tzricha legufah.” According to R. Shimon, it is “patur aval assur” and according to R. Yehudah, it is “chayav.” Text #22 discusses the main purpose (“guf hamelakha”) of extinguishing, which will be relevant to the analysis of the next text.


Text #23 (Shabbat 42a) and Text #24 (Rambam, Hilchot Shabbat 1:8 and Raabad): This gemara compares the extinguishing of wood and metal. Shmuel says that one may extinguish a burning piece of metal so that it not cause injury, but not an ember of wood. The gemara questions this assumption since it appears that Shmuel’s position is based on the concept of “melakha she’eino tzricha legufah.” If so, one should also be allowed to extinguish the wood in order to protect people from injury. The gemara answers that in “melakha she’eino tzricha legufah” Shmuel holds like R. Yehudah that it is “chayav” (a Torah prohibition). Text #24 shows that the Rambam goes according to R. Yehudah in “melakha she’eino tzricha legufah” while most Rishonim go according to R. Shimon, as indicated in the Raabad.


Here too is an opportunity to introduce physics into the unit. A good example of burning metal is the tungsten filament light bulb. The workings of the light bulb should be explained to the students as this discussion has implications regarding the status of the light bulb on Shabbat.


Text #25 (Shulchan Aruch Orech Chayim 335) and Text #26 (Yerushalmi Yoma 3): According to the Shulchan Aruch, one may extinguish an ember of metal or wood on Shabbat in order to protect people from injury. According to the Rambam, one may extinguish the metal, but not the wood.


Apparently, the Shulchan Aruch was satisfied with the question of the Gemara on Shmuel’s position, but not with the answer (for one could ask the same question on the answer – i.e. “If so, then extinguishing metal should also be forbidden ?”). The position of the Shulchan Aruch is based on the concept of “melakha she’eino tzricha legufah” and does not, therefore, follow the position of Shmuel. The Rambam (who goes according to the position of R. Yehudah, unlike most Rishonim), however, holds that the gemara’s answer is saying that the reason behind Shmuel’s opinion is not “melakha she’eino tzricha legufah.” Rather, as the Magen Avraham points out, the Rambam holds that burning metal is not fire. This idea is found as well in the Yerushalmi (text #25) in the name of R. Yehudah.


This Gemara and its two interpretations have interesting applications. According to the Rambam, igniting a tungsten filament bulb would be a Rabbinical prohibition only since it is not really fire. According to the Shulchan Aruch, however, it would be a more serious transgression.


Conclusion: The students now have enough information to consider the implications of the use of electricity and thermostat-controlled devices (including many central heating and air conditioning systems. There are differences of opinions among the poskim regarding the thermostat controlled refrigerator. Many permit its use based on the fact that it is not a “melekhet machshevet,” and particularly based on the concept of “davar she’eino mitkaven.” Some permit opening the refrigerator only when it is running already. The Chazon Ish, however, did not permit it. He recommended a refrigerator that would turn on and off automatically at set intervals, a feature that is available in many refrigerators manufactured in Israel.