A double portion of the Mahn came down on Friday, because people would not be allowed to carry it to their houses on Shabbos. This way, they had their Shabbos food in their houses before Shabbos. They were also told be sure to cook or bake the Mahn before Shabbos began.
There is a discussion in the Mechilta here about exactly how the Mahn was prepared. Rebbi Yehoshua holds that the mere thought of baking would miraculously transform the Mahn into a baked preparation, and the thought of cooking would render the Mahn cooked. Rebbi Elazar HaModa'i says that it would taste as if it were prepared the way you wanted, but there was no physical change. (I suppose this is what underlies the machlokes Reb Ami and Reb Asi in Yoma 74b whether the tribulation of the Mahn was not having food in the pantry or not seeing the food you're tasting.)
Two years ago, I posted a discussion about BCI technology, with which a person can control a computer via thought patterns. Absolutely no movement is involved; sensors detect and analyze variations in brain wave activity and the program responds to this variation. Once you can move and click a cursor with brain activity, you can do every single one of the thirty nine melachos of Shabbos without lifting a finger.
BCI stands for brain–computer interface (BCI). Other terms used are mind-machine interface (MMI), and direct neural interface, and brain–machine interface (BMI), For the latest on BCI, go here.
את אשר תאפו אפו ואת אשר תבשלו בשלו
There is a discussion in the Mechilta here about exactly how the Mahn was prepared. Rebbi Yehoshua holds that the mere thought of baking would miraculously transform the Mahn into a baked preparation, and the thought of cooking would render the Mahn cooked. Rebbi Elazar HaModa'i says that it would taste as if it were prepared the way you wanted, but there was no physical change. (I suppose this is what underlies the machlokes Reb Ami and Reb Asi in Yoma 74b whether the tribulation of the Mahn was not having food in the pantry or not seeing the food you're tasting.)
יאמר אליהם הוא אשר דבר ה', אמרו לו אימתי אמר להם מחר: את אשר תאפו אפו, ר' יהושע אומר מי שהוא רוצה אפוי היה מתאפה לו והרוצה מבושל היה מתבשל לו. ר' אלעזר המודעי אומר הרוצה לאכול דבר אפוי היה טועם בו כל אפויים שבעולם והרוצה לאכול דבר מבושל היה טועם בו כל בשולים שבעולם ר' אליעזר אומר על אפוי אפו ועל מבושל בשלו הא כיצד יום טוב שחל להיות ערב שבת מנין שאין רשאין לא לאפות ולא לבשל אלא אם כן עירבו ת"ל את אשר תאפו אפו אפו על אפוי ובשלו על מבושל:
Two years ago, I posted a discussion about BCI technology, with which a person can control a computer via thought patterns. Absolutely no movement is involved; sensors detect and analyze variations in brain wave activity and the program responds to this variation. Once you can move and click a cursor with brain activity, you can do every single one of the thirty nine melachos of Shabbos without lifting a finger.
BCI stands for brain–computer interface (BCI). Other terms used are mind-machine interface (MMI), and direct neural interface, and brain–machine interface (BMI), For the latest on BCI, go here.
Having seen this Mechilta, and some other sources, it is time for an update. Some of this material was briefly mentioned in the original post, but most of it is new, like the Mechilta.
Harav Tzvi Pesach Frank, in his pirush on Chumash here and in a teshuva, and the Mirkeves Hamishna and the Netziv in their peirushim on the Mechilta, note that our Mechilta shows that according to Rebbi Yehoshua, this form of melacha is assur on Shabbos; that it needed to be done before Shabbos, even though the cooking and baking would be effected by thought alone.
(Please note that this Mechilta is completely incomprehensible- to me- if we're going to read it literally from a halachic standpoint. Even if thought would make it cooked, the thought did not cook it. I'm not talking about the Bishul b'chama/Bishul b'eish issue, I'm talking about no bishul at all happening. It turned it into a food that was identical with something that had been cooked. It was נתהפך to become a thing that is Mevushal, but there is no event of בישול taking place. What we have here is like a thought that takes an object that was in a Reshus Hayachid and makes it re-appear in a Reshus Harabbim. There was no akira, there was no ha'avara, there was no hanacha. Before it was there, now it's here. We have the shiur of a melacha, and we have the effect of a melacha, but the melacha wasn't done. There's a consequence without a sequence. Bishlema by netilas neshama, causing death is the melacha, and however you do it it's assur. Here, it's the act of bishul that is assur and the fact that the food gets cooked is for the chiyuv on a shiur of the melacha. It's like Zorei'ah, planting: the issur is the planting, and the fact that the seed sprouts is just a test of whether your act of planting was a melacha. Here, it's impossible that such a thing would be bishul. Maybe it would be makeh b'patish, but that doesn't make sense either, since it was perfectly good even without the machshava. But I don't care that this is shver. The Achronim see the Mechilta as a raya to this question, so I'm going with that. I guess the problem is not bishul, but Mesaken Manna, like the next source says.)
The Moshav Zkeinim in Bamidbar (11:8) says the following:
(Please note that this Mechilta is completely incomprehensible- to me- if we're going to read it literally from a halachic standpoint. Even if thought would make it cooked, the thought did not cook it. I'm not talking about the Bishul b'chama/Bishul b'eish issue, I'm talking about no bishul at all happening. It turned it into a food that was identical with something that had been cooked. It was נתהפך to become a thing that is Mevushal, but there is no event of בישול taking place. What we have here is like a thought that takes an object that was in a Reshus Hayachid and makes it re-appear in a Reshus Harabbim. There was no akira, there was no ha'avara, there was no hanacha. Before it was there, now it's here. We have the shiur of a melacha, and we have the effect of a melacha, but the melacha wasn't done. There's a consequence without a sequence. Bishlema by netilas neshama, causing death is the melacha, and however you do it it's assur. Here, it's the act of bishul that is assur and the fact that the food gets cooked is for the chiyuv on a shiur of the melacha. It's like Zorei'ah, planting: the issur is the planting, and the fact that the seed sprouts is just a test of whether your act of planting was a melacha. Here, it's impossible that such a thing would be bishul. Maybe it would be makeh b'patish, but that doesn't make sense either, since it was perfectly good even without the machshava. But I don't care that this is shver. The Achronim see the Mechilta as a raya to this question, so I'm going with that. I guess the problem is not bishul, but Mesaken Manna, like the next source says.)
The Moshav Zkeinim in Bamidbar (11:8) says the following:
מושב זקנים
בהעלותך במדבר י״א ח
ובשלו בפרור. פרש״י שלא ירד לקדירה מעולם, מלמד שהיה משתנה להם לכל המתבשלים, וכן פי׳ לגבי וטחנו מלמד שמשתנה לכל הנטחנים, מפני שלא היו טוחנין אותו. ויש מפרשים שטו העם צדיקים מוצאים אותו על פתח אהליהם בלי טורח, ורשעים היו מוצאים אותו כשהיו שטים על פני המדבר ולקטים דרך צער וטורח. וכן דכו במדוכה ובשלו בפרור לרשעים והצדיקים לצונן. דכתיב (במדבר ט"ו ל"ב) ויהיו בני ישראל וכו' וימצאו איש מקושש עצים ולמה אלא מפני שהיה רוצה לבשל. ועוד אמרינן בסיפרי ועשו אותו עוגות וכו' ותימה הא כתיב (שמות ט״ז כ״ג) את אשר תאפו אפו ואת אשר תבשלו בשלו ואת כל העודף, אלמא היה נאפה ומתבשל ואין לומר לאו דווקא אפו אלא תחשבו עליו, ולדבר(י) המתבשל למה היה אסור בשבת לחשוב עליו שיש בו טעם תבשיל. וי"ל (דלשון) (דכיוו) דלא היה מתהפך אלא על פי דבורו לתבשיל חשוב תקון דהא אפילו הפרת נדרים לצורך שבת איבעיא לן בנדרים (ע"ז א') ובסוף שבת (קנ״ז א') אי שרי בשבת ואע"ג דהתם שרי הכא חשיב תקון.
which means that he holds it is assur, although he says דבורו.
On the other hand, Tosfos in several places indicates that it would be muttar; Fact 1.Designating Truma on Shabbos is assur under Mesaken Manna, a toldah of Makkeh Be'Patish. Fact 2. Although lechatchila one should not designate Truma with thought alone, if one does so it is effective. Combining Fact 1 and 2, Tosfos in Gittin 31a DH Bemachshava, and in Chulin 7a DH Vedilma and Bechoros 59a DH Bemachshava says that to do so on Shabbos with thought alone would be muttar. Also, the Shittah in Beitza 34b says this. (It's easy to mis-read Tosfos, but what he's saying is that even though machshava would be effective and muttar as far as hilchos Shabbos are concerned, the possibility of doing it with machshava is not sufficient to be mattir a physical hafrasha.)
The Achiezer in 2:49:4 talks about our Tosfos, and mentions that he has several problems with Tosfos' Shittah which he does not answer. But he says that even according to Tosfos, that it's muttar to be mafrish on Shabbos with thought alone, that's only because Tevel has inherent Truma potential, so you're only designating which part is Truma. But by Hekdesh, where you're creating an entirely new status, and this status causes a transfer of ownership, such a machshava is like a maaseh and would be assur on Shabbos. But he says that this is only because ownership transfers generate a concern that you might write, and so are assur miderabanan. The implication is that a real melacha, if done with Machshava, would be muttar.
Along the same lines, see Reb Akiva Eiger brought in the Shaar Tziyun in 633 sk 14, regarding a too-tall sukkah that has a pile of dirt in middle, and before yomtov you weren't mevateil the dirt, that he is not sure if if it is muttar to be mentally mevateil the dirt to the ground, because it would make the Sukka kasher and therefore be mesaken manna/makeh b'patish. I cannot find this RAE anywhere except this Shaar Tziyun. Anyway, from this RAE is appears that he's mesupak regarding the issue of mesaken manna with machshava.
And the best part- Reb Meir Don Plotzki (Kli Chemda) in Beshalach proposes that there is a difference between Shabbos and Yomtov. On Shabbos, which is an eternal and immutable commemoration of Hashem's Shvisa creating the world through His Machshava, the issur includes melacha that is done with machshava. But Yomtov, whose kedusha is created by Beis Din, by humans, the issur is only on melacha that is done with an act, the human sort of melacha. Wouldn't that be interesting, to be mattir BCI melacha on Yomtov but not on Shabbos?
I found a nice article on this topic. He cites most, if not all, of my references, here. Here's his summation:
Another update:
First, I saw Rav Carlebach's sefer on Chumash has a discussion about this.
Second, another discussion with new sources is in the end of the new Mishnas Reb Akiva Eiger in his additions, #160, here.
Another update:
Gil Student has a nice post on this topic, in which he quotes R Zalmen Menachem Koren who said the question was asked to Reb Shlomo Zalmen Auerbach. I am posting the article here, and it is available in situ here.
I. Bionic Men
Reports, albeit somewhat dubious, are circulating regarding Russian development of combat exoskeletons that can mechanically increase the strength and endurance of soldiers. Worn like body armor, these artificial extensions of the body are expected, within five years, to receive direction through brain waves. When a soldier thinks about moving his arm or leg, the mechanical extension will move, thereby multiplying the soldier’s strength. While combat is almost always a case of life-threatening danger that overrides the rules of Shabbos, the tantalizing reports still raise the question of whether such technology can be used on Shabbos in non-combat situations.
The basic technology already exists. Computers have already been developed that can receive instructions through brain waves. This Brain Computer Interface (BCI) technology currently requires direct contact with the skull but the possibility of remote connection, a sort of brain wifi, is certainly conceivable. I’m hardly an expert so it may already exist and I just do not know about it. I see three questions related to Shabbos with this technology.
First, can we use BCI to perform a forbidden labor? Can I command, through my thoughts, a plow to plow my field or my coffee maker to brew me fresh coffee? Second, can I use this technology to utilize a machine to do something that is not otherwise forbidden, such as turning the page in a book or lifting a fork full of food? (We’ll get to the third question at the end of this essay).
II. Thinking Labor
Rav Shlomo Zalman Auerbach was asked this question, apparently multiple times. He believed that there is a Talmudic precedent for prohibiting an activity on Shabbos that is done through thought (beyond thinking about business and similar thoughts, which is a separate issue). R. Zalman Menachem Koren, the editor of Rav Auerbach’s writings on electricity (Me’orei Eish Ha-Shalem, vol. 2 pp. 765-766), discusses Rav Auerbach’s oral response. Rav Auerbach pointed to the prohibition against designating food as terumah, the portion given to priests and forbidden to others, on Shabbos (Tosafos, Gittin 31a sv. be-machashavah). Even an activity that consists of thought can be forbidden.
In one of his earliest writings (Me’orei Eish, ch. 4), Rav Auerbach quotes a responsum by Rav Avraham Walkin (Zekan Aharon vol. 1 no. 15), in which the author argued that someone who miraculously cooks through thought or speech violates a biblical prohibition. Rav Walkin proves this from the man (manna) that the Jews are in the Desert. The Torah (Ex. 16:23) forbids cooking the man on Shabbos. However, the man required no preparation–you merely thought what you want and it tasted that way. Clearly, Rav Walkin argues, cooking through thought is biblically forbidden. Rav Auerbach rejects this entire line of argument (although not necessarily the conclusion) because the Torah only forbids cooking with fire, not miraculous cooking. Whatever you may be doing wrong by thinking man to be cooked, it isn’t cooking.
Rav Yisrael Rosen (Be-Chatzros Beis Hashem, p. 90) writes that he asked Rav Auerbach the same question and received the same answer about designating terumah. However, Rav Rosen challenges this proof. He points out that designating terumah violates the rabbinic prohibition of fixing an object. If so, it is not a Shabbos rule that thought can violate the prohibition but a function of designating terumah. Since the rules of terumah allow thought, the food is “fixed” and the Shabbos rules are violated. There is no general rule here to be extracted that Shabbos can be violated by thought.
Rav Rosen quotes Rav Meir Dan Plotzki (Keli Chemdah, Beshalach) who also attempts to prove from the cooking of the man that a forbidden labor caused by thought is prohibited. However, Rav Auerbach’s above objection should apply similarly. Rav Plotzki also gets philosophical. He points out that on Shabbos, we rest like God did after creating the world. Since God created the world through thought, a labor that is caused by thought is also forbidden. Although one can counter that God created the world through speech, it is not clear to me whether divine speech and divine thought are distinct.
III. Miraculous Labor
Rav Rosen briefly raises the idea that performing a forbidden activity through thought is comparable to performing it using supernatural powers. For example, killing someone by invoking God’s name or writing by asking a question of the Urim Ve-Tumim. If directly causing a labor by speaking is allowed, then certainly causing it by thinking is permitted. Rav Shay Schachter advances this argument in a recent lecture, citing many more examples. He quotes a responsum by Rav Chaim Palaggi (Lev Chaim, vol. 2 OC 188), in which the author permits extinguishing a fire on Shabbos supernaturally (with a segulah), such as reciting Psalm 98.
I believe his father, Rav Hershel Schachter, implies such a position in an article. In Be-Ikvei Ha-Tzon (p. 47), the senior Rav Schachter writes in regard to gerama and what is required for an act to be forbidden on Shabbos:
אף דבעינן מעשה האדם, לאפוקי שוא״ת ומחשבה, מכ״מ כח גברא לא בעינן
Even though we need a human action–as opposed to sitting doing nothing and thinking–we do not need human power
Maybe I am overreading this brief phrase but I think it might permit otherwise forbidden activities caused by thought.
IV. Natural Labor
However, Rav Asher Weiss (in an online essay, perhaps from his book on Exodus), rejects the comparison to miracles offered by the younger Rav Schachter. Rav Weiss argues that miraculous and supernatural actions are inherently different from natural causation. A supernatural activity is really caused by God, not man, and therefore is permitted. But when a person directly causes a forbidden activity, even if just by thinking, then it makes sense to say that he has effectively pushed the plow himself.
However, lacking a definitive proof, Rav Weiss hedges, saying that at best causing a forbidden activity by thinking constitutes gerama, which is rabbinically forbidden except in exigent circumstances. He concludes that whether this constitutes direct or indirect labor requires more study, but it is definitely forbidden under normal circumstances.
V. Extended Human
However, this discussion only answers the first question: can you use thought to perform a forbidden action? Regarding an electronic prosthetic limb, the issue turns to whether you may use thought to move an electronic device. It is not entirely the same for two reasons:
First, electronic motion may be only rabbinically prohibited. Second, and perhaps more importantly, the device itself might be considered part of the person, which brings us to the third question: what is the distinction between a person and the machines he uses? Some today argue to an extreme that your computers are an extension of your own mind. More moderate thinkers suggest that artificial appendages become part of you. Is a hearing aid distinct from you? A pacemaker? An artificial heart? If an artificial limb is considered part of you, then you may use it on Shabbos like you use your arm.
Personally, I’m a simple man and look at the issue simply. If it’s organic then it is part of you, even a donated organ and even if grown in a laboratory. If it is inorganic, even partially, then it is not part of you. If and when they make completely organic computers, then maybe that can become part of you, as well. I am not a halakhic authority so my conclusions are tentative and should not be followed. But it would seem that this line of thinking implies that artificial body parts that violate rabbinic Shabbos prohibitions (absent the considerations of thought, discussed above) may only be used by someone who would otherwise be defined as ill but not life threatening. Similarly, artificial body parts that violate biblical prohibitions may only be used by someone who would otherwise be in a life threatening situation. I am not aware what halakhic authorities have said on this subject. (In short, the Bionic Man is assur according to some authorities.)
When it comes to exoskeletons, we have to ask whether they are external to the human body. If they are, as I suggest, then we arrive at the dispute above. According to Rav Shlomo Zalman Auerbach and Rav Asher Weiss, they are forbidden. According to Rav Shay Schachter and possibly his father, Rav Hershel Schachter, this might be allowed (I did not hear the younger Rav Schachter reach a definitive conclusion). Rav Rosen also seems to lean toward leniency but does not reach a final conclusion.
- In the comments on that post, someone wrote the following.
UPDATE FEBRUARY 2019
I decided that even if machshava would be assur on Shabbos, it could not possibly be more assur than Mechameir achar Be'heima. I'm not talking about Shvisas Be'heima, which only applies to your own animal, I'm talking about Mechameir, a general issur to cause an animal to do melacha by walking after it and doing what farmers do to make their animals work. Obviously, it is not the animal we're worried about by mechameir, because mechamer applies to any animal, while shvisas only applies to your own animal, according to the Rashba and Ran in Shabbos 153b. If so, the issur is the fact that you're getting a melacha done not beyadayim. BCI can not possibly be more assur than that. This means that at worst, it would be a lahv, maybe a bittul assei (see Minchas Chinuch 32 after the Massach on mechameir) not the issur melacha mammosh.
Along the same lines, see Reb Akiva Eiger brought in the Shaar Tziyun in 633 sk 14, regarding a too-tall sukkah that has a pile of dirt in middle, and before yomtov you weren't mevateil the dirt, that he is not sure if if it is muttar to be mentally mevateil the dirt to the ground, because it would make the Sukka kasher and therefore be mesaken manna/makeh b'patish. I cannot find this RAE anywhere except this Shaar Tziyun. Anyway, from this RAE is appears that he's mesupak regarding the issue of mesaken manna with machshava.
And the best part- Reb Meir Don Plotzki (Kli Chemda) in Beshalach proposes that there is a difference between Shabbos and Yomtov. On Shabbos, which is an eternal and immutable commemoration of Hashem's Shvisa creating the world through His Machshava, the issur includes melacha that is done with machshava. But Yomtov, whose kedusha is created by Beis Din, by humans, the issur is only on melacha that is done with an act, the human sort of melacha. Wouldn't that be interesting, to be mattir BCI melacha on Yomtov but not on Shabbos?
I found a nice article on this topic. He cites most, if not all, of my references, here. Here's his summation:
סקירת השיטות שראינו, מהן ניתן להפיק שיטה הלכתית בנוגע ל-BCI:
א. הגרשז"א – המחשבה כמעשה (בהלכות מסוימות) לענין שבת.
ב. הרב רוזן – בדיקת התוצאות הסופיות של תהליכים (גם פנימיים) וקישורם למקורם.
ג. עמדת ה'חומרא' של הכלי-חמדה – כשעשיית המלאכה נעשית כרגיל על ידי המחשבה, אזי זו איננה מנגנון של כ'לאחר-יד' גרידא.
ד. עמדת ה'קולא' של הכלי-חמדה – פעולה המתבצעת על ידי מחשבה אינה מלאכה גמורה בגידרה, אלא 'רק' איסורא.
ה. הקהילות יעקב – מעמד של 'עדיף מכלאחר-יד' לפעולה סגולית בהלכות שבת, שלא כדרכה.
ו. הקהילות יעקב – דרכה של פעולה כזו היא תמיד ה'לא טבעית', לא גזרו חכמים בה.
ז. הרב זאב לב (והגרשז"א) – החילוק בין החפצא לגברא באדם ובפעולותיו בעולם. זהו היחס המפורש ביותר לנושא, ובשילוב עם חילוק החפצא/גברא זהו פיתוח של מערך מחשבתי עם השלכות הלכתיות קונקרטיות.
First, I saw Rav Carlebach's sefer on Chumash has a discussion about this.
Second, another discussion with new sources is in the end of the new Mishnas Reb Akiva Eiger in his additions, #160, here.
Another update:
Gil Student has a nice post on this topic, in which he quotes R Zalmen Menachem Koren who said the question was asked to Reb Shlomo Zalmen Auerbach. I am posting the article here, and it is available in situ here.
I. Bionic Men
Reports, albeit somewhat dubious, are circulating regarding Russian development of combat exoskeletons that can mechanically increase the strength and endurance of soldiers. Worn like body armor, these artificial extensions of the body are expected, within five years, to receive direction through brain waves. When a soldier thinks about moving his arm or leg, the mechanical extension will move, thereby multiplying the soldier’s strength. While combat is almost always a case of life-threatening danger that overrides the rules of Shabbos, the tantalizing reports still raise the question of whether such technology can be used on Shabbos in non-combat situations.
The basic technology already exists. Computers have already been developed that can receive instructions through brain waves. This Brain Computer Interface (BCI) technology currently requires direct contact with the skull but the possibility of remote connection, a sort of brain wifi, is certainly conceivable. I’m hardly an expert so it may already exist and I just do not know about it. I see three questions related to Shabbos with this technology.
First, can we use BCI to perform a forbidden labor? Can I command, through my thoughts, a plow to plow my field or my coffee maker to brew me fresh coffee? Second, can I use this technology to utilize a machine to do something that is not otherwise forbidden, such as turning the page in a book or lifting a fork full of food? (We’ll get to the third question at the end of this essay).
II. Thinking Labor
Rav Shlomo Zalman Auerbach was asked this question, apparently multiple times. He believed that there is a Talmudic precedent for prohibiting an activity on Shabbos that is done through thought (beyond thinking about business and similar thoughts, which is a separate issue). R. Zalman Menachem Koren, the editor of Rav Auerbach’s writings on electricity (Me’orei Eish Ha-Shalem, vol. 2 pp. 765-766), discusses Rav Auerbach’s oral response. Rav Auerbach pointed to the prohibition against designating food as terumah, the portion given to priests and forbidden to others, on Shabbos (Tosafos, Gittin 31a sv. be-machashavah). Even an activity that consists of thought can be forbidden.
In one of his earliest writings (Me’orei Eish, ch. 4), Rav Auerbach quotes a responsum by Rav Avraham Walkin (Zekan Aharon vol. 1 no. 15), in which the author argued that someone who miraculously cooks through thought or speech violates a biblical prohibition. Rav Walkin proves this from the man (manna) that the Jews are in the Desert. The Torah (Ex. 16:23) forbids cooking the man on Shabbos. However, the man required no preparation–you merely thought what you want and it tasted that way. Clearly, Rav Walkin argues, cooking through thought is biblically forbidden. Rav Auerbach rejects this entire line of argument (although not necessarily the conclusion) because the Torah only forbids cooking with fire, not miraculous cooking. Whatever you may be doing wrong by thinking man to be cooked, it isn’t cooking.
Rav Yisrael Rosen (Be-Chatzros Beis Hashem, p. 90) writes that he asked Rav Auerbach the same question and received the same answer about designating terumah. However, Rav Rosen challenges this proof. He points out that designating terumah violates the rabbinic prohibition of fixing an object. If so, it is not a Shabbos rule that thought can violate the prohibition but a function of designating terumah. Since the rules of terumah allow thought, the food is “fixed” and the Shabbos rules are violated. There is no general rule here to be extracted that Shabbos can be violated by thought.
Rav Rosen quotes Rav Meir Dan Plotzki (Keli Chemdah, Beshalach) who also attempts to prove from the cooking of the man that a forbidden labor caused by thought is prohibited. However, Rav Auerbach’s above objection should apply similarly. Rav Plotzki also gets philosophical. He points out that on Shabbos, we rest like God did after creating the world. Since God created the world through thought, a labor that is caused by thought is also forbidden. Although one can counter that God created the world through speech, it is not clear to me whether divine speech and divine thought are distinct.
III. Miraculous Labor
Rav Rosen briefly raises the idea that performing a forbidden activity through thought is comparable to performing it using supernatural powers. For example, killing someone by invoking God’s name or writing by asking a question of the Urim Ve-Tumim. If directly causing a labor by speaking is allowed, then certainly causing it by thinking is permitted. Rav Shay Schachter advances this argument in a recent lecture, citing many more examples. He quotes a responsum by Rav Chaim Palaggi (Lev Chaim, vol. 2 OC 188), in which the author permits extinguishing a fire on Shabbos supernaturally (with a segulah), such as reciting Psalm 98.
I believe his father, Rav Hershel Schachter, implies such a position in an article. In Be-Ikvei Ha-Tzon (p. 47), the senior Rav Schachter writes in regard to gerama and what is required for an act to be forbidden on Shabbos:
אף דבעינן מעשה האדם, לאפוקי שוא״ת ומחשבה, מכ״מ כח גברא לא בעינן
Even though we need a human action–as opposed to sitting doing nothing and thinking–we do not need human power
Maybe I am overreading this brief phrase but I think it might permit otherwise forbidden activities caused by thought.
IV. Natural Labor
However, Rav Asher Weiss (in an online essay, perhaps from his book on Exodus), rejects the comparison to miracles offered by the younger Rav Schachter. Rav Weiss argues that miraculous and supernatural actions are inherently different from natural causation. A supernatural activity is really caused by God, not man, and therefore is permitted. But when a person directly causes a forbidden activity, even if just by thinking, then it makes sense to say that he has effectively pushed the plow himself.
However, lacking a definitive proof, Rav Weiss hedges, saying that at best causing a forbidden activity by thinking constitutes gerama, which is rabbinically forbidden except in exigent circumstances. He concludes that whether this constitutes direct or indirect labor requires more study, but it is definitely forbidden under normal circumstances.
V. Extended Human
However, this discussion only answers the first question: can you use thought to perform a forbidden action? Regarding an electronic prosthetic limb, the issue turns to whether you may use thought to move an electronic device. It is not entirely the same for two reasons:
First, electronic motion may be only rabbinically prohibited. Second, and perhaps more importantly, the device itself might be considered part of the person, which brings us to the third question: what is the distinction between a person and the machines he uses? Some today argue to an extreme that your computers are an extension of your own mind. More moderate thinkers suggest that artificial appendages become part of you. Is a hearing aid distinct from you? A pacemaker? An artificial heart? If an artificial limb is considered part of you, then you may use it on Shabbos like you use your arm.
Personally, I’m a simple man and look at the issue simply. If it’s organic then it is part of you, even a donated organ and even if grown in a laboratory. If it is inorganic, even partially, then it is not part of you. If and when they make completely organic computers, then maybe that can become part of you, as well. I am not a halakhic authority so my conclusions are tentative and should not be followed. But it would seem that this line of thinking implies that artificial body parts that violate rabbinic Shabbos prohibitions (absent the considerations of thought, discussed above) may only be used by someone who would otherwise be defined as ill but not life threatening. Similarly, artificial body parts that violate biblical prohibitions may only be used by someone who would otherwise be in a life threatening situation. I am not aware what halakhic authorities have said on this subject. (In short, the Bionic Man is assur according to some authorities.)
When it comes to exoskeletons, we have to ask whether they are external to the human body. If they are, as I suggest, then we arrive at the dispute above. According to Rav Shlomo Zalman Auerbach and Rav Asher Weiss, they are forbidden. According to Rav Shay Schachter and possibly his father, Rav Hershel Schachter, this might be allowed (I did not hear the younger Rav Schachter reach a definitive conclusion). Rav Rosen also seems to lean toward leniency but does not reach a final conclusion.
- In the comments on that post, someone wrote the following.
The Mishnas Yaakov (R Yaakov Rosenthal, Dayan of Haifa) seems to learn the Tosfos as I did, that there is no issur of hafrasha on Shabbos bemachshava, and seems to indicate that the rashash learned the same way.
UPDATE FEBRUARY 2019
I decided that even if machshava would be assur on Shabbos, it could not possibly be more assur than Mechameir achar Be'heima. I'm not talking about Shvisas Be'heima, which only applies to your own animal, I'm talking about Mechameir, a general issur to cause an animal to do melacha by walking after it and doing what farmers do to make their animals work. Obviously, it is not the animal we're worried about by mechameir, because mechamer applies to any animal, while shvisas only applies to your own animal, according to the Rashba and Ran in Shabbos 153b. If so, the issur is the fact that you're getting a melacha done not beyadayim. BCI can not possibly be more assur than that. This means that at worst, it would be a lahv, maybe a bittul assei (see Minchas Chinuch 32 after the Massach on mechameir) not the issur melacha mammosh.
