The Definition of Shevu’at Shav

The issur of shevu’at sheker is mentioned at least three times in the Torah, but the Torah delineates a separate prohibition for a shevu’at shav, typically translated as a “pointless shevu’a.” The mishna (29a) iterates four different examples of shveu’at shav: Swearing in contradiction of something patently obvious, swearing about something impossible, swearing to violate a mitzva, and swearing to reverse a previously declared shevu’a. In this shiur, we will probe the relationship between a shevu’at shav and a classic shevu’at sheker.

Is the prohibition of shevu’at shav merely a more intense form of shevu’at sheker? A classic shevu’a le-haba isn’t sheker when first declared, since the oath may be ultimately fulfilled. It only emerges as false in the wake of non-execution. Even a shevu’a le-she'avar or past shevu’a that is immediately false based on previous conduct is only a personal “falsehood,” inasmuch as the individual didn’t conduct himself as he purported to in his oath. The behavior stated in the oath could in theory be true. By contrast, shevu’at shav – for example, swearing in contradiction of an obvious reality (that a piece of gold is really silver) – is extreme dishonesty, since there is no way that gold can ever be silver and this is universal falsehood. If shevu’a shav is defined as extreme untruth, it is structurally analogous to shevu’at sheker.

Alternatively, shevu’at shav may comprise a completely different prohibition – not an extreme untruth, but rather a frivolous and wasteful shevu’a. By swearing to contradict something obvious, a person has frivolously and without any purpose mentioned the name of HaKadosh Barukh Hu. A shevu’at sheker isn’t frivolous, as the person taking the oath may be attempting to convince another of a (false) statement. An oath about something obviously untrue is just an abject waste, and this affront to the name of HaKadosh Barukh Hu entails an entirely different prohibition.

An interesting gemara (20b) mentions that shav and sheker "are one," which the gemara interprets to mean that they were delivered by HaKadosh Barukh Hu at Har Sinai through one integrated statement (much in the same manner that zakhor and shamor were fused and jointly delivered). This would definitely presume that they are structurally analogous. It is unclear, however, whether the gemara maintains this view in its conclusion.

Perhaps the most obvious nafka mina to help clarify the nature of shevu’at shav pertains to an oath to corroborate something obvious. The mishna describes a situation in which an obvious truth is contradicted as shav. The Yerushalmi adds a scenario wherein an obvious truth is confirmed (for example, someone who swears that a piece of gold is gold). If a shevu’at shav is an extreme form of sheker, this example would not be considered shav, as no falsehood has been uttered. If, however, shav entails a frivolous shevu’a, it would apply equally to contradictions and confirmations of obvious truths, each of which would entails a wasteful shevu’a.

A second question pertains to someone who mentions HaKadosh Barukh Hu's name in vain without taking a formal shevu’a. Based on a gemara in Berakhot (21), the Rambam (Berakhot 1:15) claims that this scenario also violates a shevu’at shav. Once again, this expansion of shevu’at shav indicates that the core of the prohibition is the frivolous and wasteful mention of HaKadosh Barukh Hu's name. This frivolity occurs anytime the Name is mentioned without any apparent purpose, whether in the framework of a shevu’a or as a stand-alone mention. If shevu’at shav were a form of falsehood, it would be completely inapplicable to an autonomous statement taken without a shevu’a framework.

An additional example of a shevu’a that may not be an extreme sheker but may be frivolous relates to a shevu’a to fulfill a mitzva. The mishna defines a shevu’a to suspend a mitzva as shav. It is unclear, however, whether this definition is based upon the frivolity of attempting to omit a mitzva or upon the inevitable sheker of this oath, since Halacha mandates the performance of the mitzva (and cancellation of the shevu’a). The test case would be a shevu’a to fulfill a mitzva. If this is also considered shav, apparently it is frivolous to swear about an action already mandated by mitzva whether to violate or violate. If shav were based primarily upon extreme sheker, it would not apply to a shevu’a that would be upheld and fulfilled by performance of a mitzva activity.

The gemara in Nedarim (8a) discusses a shevu’a to perform a mitzva, and the Rambam (Shevuot 5:16) at least according to some reading claims that shevu’at shav has been violated. Evidently, this supports his position that any pointless mention of HaKadosh Barukh Hu's name is a violation of shav. Corroborating an obvious truth as well as mentioning HaKadosh Barukh Hu's name independent of a shevu’a framework are examples of shav because they are frivolous. Similarly, a shevu’a to perform a mitzva is frivolous, even though it will not be proven false.

Those who argue with the Rambam and claim that a shevu’a to uphold a mitzva is not shav can adopt multiple approaches, including:

1. Unlike a shavu’a to break a mitzva, a shevu’a to perform a mitzva is chal; even though a shevu’a to avoid a prohibition is redundant and meaningless, one to uphold a mitzva is different
2. Even if the shevu’a to uphold a mitzva does not entail an actual halakhic oath, it still provides psychological motivation toward mitzva performance. Since it serve a purpose, it isn’t completely frivolous and cannot be considered shav.

An additional proof that shevu’at chav is defined as a pointless shevu’a can be gleaned from an interesting machloket about the range of “impossible” shavu’ot. As stated earlier, the mishna (29a) describes a shevu’a to perform something impossible as a shevu’at shav. The gemara provides an example: an oath not to sleep for 3 days would be shav since a person will certainly fall asleep during this duration. The Rambam (Shavuot 1:37) claims that an oath not to eat for a week would similarly be shav, since this is legally impossible – at the point of dangerous starvation, Halakha would mandate eating as pikuach nefesh, thereby rendering this scenario “impossible.” Since he takes an oath that is impossible to fulfill, he has violated shevu’at shav.

The Ran disagrees, presumably understanding shav as a form of extreme sheker. Since the starving person must ultimately decide whether to save his life and comply with Halakha by eating or whether to uphold the shevu’a by fasting and starving to death, this shevu’a is not an immediate sheker (as are other shevu’at shav).

The Ramban (consistent with his earlier statements defines shav as futile. Any attempt to contravene halakha is futile and considered shevu’at shav. Since halakha demands eating, a shevu’a to avoid it is shav. By contrast the Ran may have defined shav as extreme falsehood since there is no option for fulfillment. Since this person may violate halakha and maintain the shevu’a it can’t be extreme sheker.

Finally, the mishna (29a) describes a second shevu’a in contradiction of a previous shevu’a as an instance of shav. For example, if a person took an oath to eat and followed that by taking an oath not to eat, his second shevu’a is in violation of shav. The Rashba (Teshuva 1:702) claims that if the person repeals the first shevu’a retroactively, he no longer has violated shav. The Ratvaz (1:178) disagrees, claiming that if a shevu’a has been deemed shav at the outset, it cannot retroactively be redesigned as non-shav.

Perhaps this debate surrounds the nature of shevu’at shav. If the Rambam is correct and shav is a futile shevu’a, any subsequently emerging function will add utility and remove the tag of “frivolity” from a shevu’a. By contrast, if shav is a form of extreme sheker, it would likely de defined at the point of declaration (as typical shevu’at sheker le-she'avar is defined). Subsequent repealing of a previous shevu’a would not alter the identity of a subsequent shevu’a that was deemed shav/extreme sheker at its point of origin.