Responsibility for a Fellow's Religious Obligations

In the Book of Leviticus1 we read: "Each man will stumble over his brother." Our sages learn from this verse that every Jew is responsible for the actions of his fellow Jew.2 The verse is to be understood as if saying: "Each man will stumble over the sin of his brother." This responsibility is referred to as arvut (guarantorship).3

The Torah proclaims: "The revealed are to us and our children forever, that we must observe all the words of this Torah; the hidden things belong to the L-rd, our G‑d."4 According to the Talmud5 this is a reference to the concept of arvut. When an individual's sins are "revealed," it becomes communal responsibility—if it is within their means to prevent it. If the sin is secret, then G‑d alone pledges to mete justice upon the sinner.

Arvut also means "mixture," alluding to the fact that all our souls are actually part of one big "blend"As explained in the mystical texts, all Jewish souls constitute one entity. Our nation is likened to a large body, each soul emanating from one of its 248 limbs. From this stems our mutual responsibility for one another—because we truly are one. In fact, the word arvut also means "a mixture," alluding to the fact that all our souls are actually part of one big "blend."6

As a result of this responsibility, under certain circumstances one may say a blessing, though he himself is not obligated to recite it, for the benefit of another—to ensure that the other also fulfills his personal obligation. Though ordinarily it is forbidden to recite a blessing unless personally required to do so – as it constitutes taking G‑d's name in vain – the responsibility of another Jew is actually considered one's own obligation.

The following are some of the practical applications of this concept:

(But first a necessary preface: There is a halachic concept called shome'a k'oneh—"the listener is as the reciter." Practically this means that if two [or more] individuals are equally obligated to perform a mitzvah,7 e.g. don a tallit, one can recite the blessing8 and the other can listen, answer "Amen," and it is considered as if he, too, said the blessing.9)

• The concept of arvut allows even one who is currently not obligated to recite the blessing on a mitzvah (e.g. he has already donned his own tallit and recited the appropriate blessing) to do so for the benefit of another who does not know how to recite the blessing.10
• One may not recite a blessing over a food for another's benefit if the reciter of the blessing is not actually eating.11 The fact that another wants to eat is not considered a "shared responsibility."12
• An exception to this rule is when consuming the food or beverage is a mitzvah—such as Kiddush or the blessing on matzah at the Seder; in such an instance one may say the blessing for another (who is incapable of doing so) though the reciter already performed the mitzvah.13
• Arvut also applies to one who has not yet done a mitzvah and wishes to do so on behalf of someone else—but not for themselves. Example: If one visits a hospital patient late on Friday afternoon,14 he may say the Kiddush for the patient, though he has in mind that he does not yet want to fulfill the mitzvah of Kiddush himself (as then he would not be permitted to drive home).15
• Regarding the Shabbat daytime Kiddush, one may repeat the Kiddush for another who has not yet heard Kiddush, regardless of the listener's ability to say Kiddush. This is because this Kiddush does not include any extra blessing other than the blessing on the wine—which the one reciting the Kiddush consumes anyway.16
• Arvut is also the basis for the mitzvah of rebuking a fellow who is sinningAll the above applies uniformly to men and women, regardless of who is reciting the blessing and who is listening—in those areas where they have equal obligation to perform a mitzvah. However, women harbor no responsibility towards men in those mitzvot that they themselves are not obliged to do.17 This means that a woman may not say a blessing on shofar, lulav, or any other mitzvah that she is not obligated to fulfill (though she may if she wishes) for the benefit of a man—even if the man is unable to recite the blessing himself.
• Because of the mitzvah of chinuch (educating children), it is permissible for an adult to recite blessings – any blessing, even over foods – for children (even if they are not his own). The adult may say the blessing, even though he is not eating, and the child can say "Amen" and partake of the food.18

Arvut is also the basis for the mitzvah of rebuking a fellow who is sinning.19 Practically, this means that if one knows that another Jew is sinning, it is his responsibility to attempt to influence him not to sin. If one is unsuccessful in this endeavor, one should try again.20 Obviously, this rebuke should be expressed in a way that will be accepted by the offender, not in a way that will further estrange him. Hence, if it is apparent that the rebuke will have no effect, it is better not to rebuke at all.21