"Bal Tosif" and Its Meaning (Column 738)

"Bal Tosif" and Its Meaning

A few days ago I was put on the spot to give a class on the first chapter of Rosh Hashanah, and I decided to speak about the dispute between Tosafot and the Rashba regarding "Bal Tosif" (the prohibition of adding to the Torah) in the context of shofar blowing and more generally (Rosh Hashanah 16a–b). In the course of the class a few comments occurred to me about this sugya, and I thought to share them here in honor of the New Year.

The Flow of the Sugya

The Gemara in Rosh Hashanah 16a brings a baraita with a series of explanations for various commandments:

It was taught: R. Yehuda said in the name of R. Akiva: Why did the Torah say to bring the omer on Passover?—because Passover is the season of grain. The Holy One, blessed be He, said: Bring before Me the omer on Passover so that the grain in your fields will be blessed. And why did the Torah say to bring the Two Loaves on Shavuot?—because Shavuot is the season of the fruit of the tree. The Holy One, blessed be He, said: Bring before Me the Two Loaves on Shavuot so that the fruit of the tree will be blessed for you. And why did the Torah say to pour water on the festival [of Sukkot]? The Holy One, blessed be He, said: Pour water before Me on the festival so that the rains of the year will be blessed for you. And say before Me on Rosh Hashanah: Kingship, Remembrances, and Shofarot—Kingship so that you will crown Me over you; Remembrances so that your remembrance will come before Me for good; and with what?—with the shofar.

Here we have a series of teleological explanations for the commandments of the omer, the Two Loaves, the water libation, and the recitation of Kingship, Remembrances, and Shofarot on Rosh Hashanah. Each of these commandments is given a purpose-based rationale. At first glance, this is difficult given the rule that we do not "darshen ta‘ama dikra" (derive law from the reason of the verse; see Columns 713 – 716), i.e., that we do not interpret the commandments based on their reasons. It should be noted that most of the commandments discussed here are not derived homiletically but are explicit commandments (the water libation is a halakha le-Moshe mi-Sinai, and regarding Kingship, Remembrances, and Shofarot there is room for discussion). In those columns I explained that for such commandments the rule applies that we do not use the reason to interpret the halakhic contours of the mitzvah.

However, this is only an apparent difficulty, since no one disputes that it is permissible to explain the reasons for the commandments (though there is at least one who disputes the value of doing so). The rule that we do not derive law from the reason addresses only whether one may use a reason in order to interpret the commandment and determine its legal boundaries (purposive interpretation). That is not what is being done here.

Immediately thereafter an amoraic statement appears:

R. Abbahu said: Why do we blow with a ram’s horn? The Holy One, blessed be He, said: Blow before Me with a ram’s horn so that I will remember for you the Binding of Isaac, son of Abraham, and I will reckon it for you as if you bound yourselves before Me.

R. Abbahu explains a law that is not explicit in the Torah but is derived by interpretation. This is an interpretive derash that does not create an independent law, and as such, one can discuss whether the rule of not deriving law from reasons applies. In any case, he too offers a reason for the commandment without using it to determine its legal contours.

But then another statement appears from R. Yitzḥak:

(And he said) +Masoret haShas: [He said]+ R. Yitzḥak: Why do we blow on Rosh Hashanah?

There are two versions at the beginning of this sentence: whether it says "amar" (he said) or "ve’amar" (and he said). Masoret haShas reads "amar" without a vav—i.e., this is an independent statement. Why does this matter? Because, precisely in light of the previous statements, the Gemara’s approach here is puzzling. The Gemara now wonders:

—Why do we blow? The Merciful One said "blow"! —Rather: why do we sound a teru‘ah? —Teru‘ah? The Merciful One said "a memorial of teru‘ah"!

At first the Gemara understands the question as asking why we blow the shofar at all, and immediately rejects this, since the Torah explicitly commands blowing, and likewise regarding the teru‘ah. In light of what we have seen so far, it is unclear why specifically here the question is dismissed this way. Even if the question was "why do we blow," one would expect an exploration of the reason for the commandment. So what if there is an explicit command? Do we not bring the omer because the Torah explicitly says to bring it on Passover?! And is the water libation not because a halakha le-Moshe mi-Sinai established it?! So why here does the Gemara refuse a reason and take it as a search for a source?

First note that the wording of the question here is different. Above, the Gemara formulates it as "mipnei mah…"—"for what reason…", which indeed inquires into the rationale. Here the formulation is "lama tokin"—"why do we blow," which can be read as a search for a source. Still, why doesn’t it simply explain that the intent was to seek a reason rather than a source? Why does the Gemara resort to a different explanation (brought immediately)?

Recall Maimonides (Rambam), Laws of Repentance 3:4:

Even though blowing the shofar on Rosh Hashanah is a decree of Scripture, there is a hint in it: "Awake, sleepers, from your sleep; slumberers, arise from your slumber. Search your deeds, return in repentance, and remember your Creator." Those who forget the truth in the vanities of time and stray all year in emptiness and purposelessness that neither benefits nor saves—look to your souls, improve your ways and your deeds. Let each leave his evil way and unworthy thoughts. Therefore, a person should see himself all year long as if he is half meritorious and half guilty, and likewise the whole world is half meritorious and half guilty. If one commits one sin, he tilts himself and the whole world to guilt and brings destruction upon them. If he performs one commandment, he tilts himself and the whole world to merit and brings salvation and deliverance to them, as it is said, "And a righteous one is the foundation of the world"—that is, the righteous one who has justified the whole world and saved it. Because of this matter, the entire House of Israel has the custom to increase in charity and good deeds and to engage in commandments from Rosh Hashanah to Yom Kippur more than throughout the year, and all arise at night in these ten days and pray in the synagogues with words of supplication until daybreak.

Here there is a possible reason for the mitzvah of shofar; I would have expected the Gemara to bring it.

In any case, apparently the wording of the question led the Gemara to understand that here the search is for a source and not a reason. For this reason they likely read "amar" without a vav, indicating that this statement is not a continuation of the previous series but a new one dealing with a different topic.

A Note on the Meaning of Command

Still, from the flow of the sugya one can glean a very fundamental point, which I have noted many times: even if we have a reason for a commandment, it is not a substitute for the source/command. Even if the Gemara were to tell us that the reason for the shofar is to awaken us to repentance, that would not be the reason we fulfill it. The reason we fulfill it is the Torah’s command; therefore, even if there is a reason, there must be in addition a command. Conversely, regarding the earlier commandments (the omer, the Two Loaves, and the water libation) for which the Gemara offers reasons, that does not obviate the need for a command (see Columns 71, 631, and others).

On the other hand, there is also a reverse novelty here: even if there is a command, and even if the reason we fulfill the mitzvah is the command and not the reason, that does not mean the mitzvah has no reason. Certainly it does, and that is why we were commanded. This is unlike those views Rambam brings in Part III of the Guide of the Perplexed that hold the commandments are decrees without reasons (see the above columns). Our sugya teaches that for every commandment or prohibition there must be both a reason and a command. One without the other does not suffice.

"To Confound the Satan"

Ultimately, the sugya remains with difficulty understanding R. Yitzḥak’s question. It concludes with a different explanation of his question:

Rather: Why do we blow and sound teru‘ah while sitting, and blow and sound teru‘ah while standing?—In order to confound the Satan.

R. Yitzḥak was not asking for the source of the mitzvah of shofar, but about the additional sets of blasts (sitting or standing—depending on the Rishonim as to which are primary and which are additional). He explains that the Sages instituted them in order to confound the Satan (please don’t ask me what that means. I was relieved to see that the Ran and the Rashba cited in the Beit Yosef explain it as referring to our evil inclination). Note that this answer touches both the question of source and of reason. Since this obligation is not biblical, the reason is also the source: it is the reason the Sages instituted it, and now we fulfill it because it is a rabbinic command.

On this explanation, the Rishonim ask how the Sages could institute such a thing when it appears to add to the Torah’s obligations, seemingly prohibited by "Bal Tosif." From here on I will address that.

Tosafot’s Approach

Tosafot s.v. "ve-tok‘in" here ask:

"They blow and sound while standing"—it is astonishing: surely this transgresses Bal Tosif.

Tosafot wonder how the Sages instituted adding blasts beyond the biblical obligation; isn’t that Bal Tosif?

Immediately they raise a potential resolution, based on the accepted distinction in the laws of Bal Tosif between the time of the mitzvah—when one transgresses by adding even without intent—and after the time of the mitzvah—when one transgresses only with intent to add to the mitzvah:

And if you will say: since he has already discharged his obligation, this is considered "not in its time," and one does not transgress…

According to this, one might resolve that after a person has already blown, any further blowing is considered not in the time of the mitzvah, and therefore he does not transgress Bal Tosif. True, even not in its time one transgresses if he intends to add to the mitzvah, but Tosafot apparently assume that intent to fulfill a rabbinic enactment is not considered intent to add to the biblical mitzvah for purposes of Bal Tosif. Therefore they raise the question only if we assume the additional blowing is during the time of the mitzvah.

But they reject this possibility:

For we say at the end of "Ra’uhu Beit Din" (28b) regarding Birkat Kohanim that one does not add a blessing of his own because [even after having blessed once] its time has not passed, since if another congregation were to come he would bless them; so too here, if another congregation were to come he would blow for them.

In the sugya in Rosh Hashanah 28 that discusses Birkat Kohanim, we see that even after performing the mitzvah it is still considered its time, since he may need to perform it for others. As with Birkat Kohanim, so with shofar blowing.

A Note on Tosafot’s Question

It is unclear whether Tosafot are challenging the court (beit din) that instituted the blasts to confound the Satan, or the people who carry out the enactment and blow. Is the legislation itself an addition to the Torah such that the legislators transgress Bal Tosif, or is the prohibition only upon the actual performers? Either way, why did Tosafot choose to challenge this enactment in particular? Why not ask about fowl with milk, secondary incest prohibitions, Ḥanukkah and Purim, netilat yadayim, tithes from non-grain produce, and tithe on wine and oil (for those Rishonim who hold only those are biblically obligated), and the like?

Moreover, do Tosafot deny the role of the Sages to legislate and decree? I have often written that the Sages were given two roles and two authorities: to legislate (rabbinic law) and to interpret (biblical law). According to Rambam, the legislative authority is itself grounded in the Torah in "lo tasur" (do not veer). But even Ramban, who learns from those verses only the authority to interpret and expound the Torah, certainly agrees that the Sages have authority to decree and institute. No one disputes this. Is Tosafot here claiming that the Sages can only interpret the Torah and not legislate and decree? It does not seem that they intend to undermine the entire legislative function of the Sages. And certainly even if Tosafot are aiming their words only at individuals and not at beit din, it would be meaningless to grant the Sages legislative power yet forbid people from observing their laws. Clearly, if they were given the authority to legislate, every Jew is obligated to keep that legislation (Column 344—on the categorical imperative—contains an extensive discussion of this reasoning).

It is possible that Tosafot understand the extra blasts "to confound the Satan" not as a rabbinic enactment but merely a recommendation. Perhaps this also explains the Gemara’s wording "why do we blow and sound," meaning "why do we do this if the law (biblical or rabbinic) does not require it?" Therefore here—and only here—Tosafot ask how it is permitted, given Bal Tosif. But where there is a rabbinic enactment or decree, Tosafot obviously see no problem of Bal Tosif.

I then saw that the Aruch LaNer here brings that the Pnei Yehoshua already asked this:

In the body of his words he suggests that Bal Tosif does not apply. The Rashba answered this question that Bal Tosif applies only when one adds on his own accord, but where the Sages stood and instituted for a need, there is no Bal Tosif. And the Pnei Yehoshua wrote that it is perplexing why Tosafot did not answer likewise.

We will see the Rashba’s words below.

The Pnei Yehoshua resolves:

He wrote to distinguish between enactments that the Sages instituted due to changing circumstances after the Giving of the Torah and that which could also have been at the time of the Giving, such as blowing both seated and standing—this does not depend on changing circumstances.

That is, if the Sages are responding to changed circumstances there is no Bal Tosif, for that is their role. But an enactment that could have existed already at Sinai does carry Bal Tosif, for the Torah should have set it then.

But the Aruch LaNer rejects this explanation:

In my opinion this is forced, for many enactments were instituted by the Sages that do not depend on changed circumstances or "degeneration of the generations," such as the decree lest one carry [on Shabbat] (29b), rabbinic "shevut" prohibitions on Shabbat (Shabbat 94b), and secondary incest prohibitions (Yevamot 20a); yet there is no Bal Tosif or Bal Tigra (do not subtract).

Therefore he proposes a different explanation:

In my opinion there is another reason why Tosafot did not answer thus: there is a difference between commandments of the Sages, which are included under "lo tasur" and upon which we recite a blessing "who has sanctified us with His commandments and commanded us," and practices (minhagim) upon which we do not bless "and commanded us." Therefore in all rabbinic commandments there is no Bal Tosif, for the Torah granted the Sages authority to institute and commanded "lo tasur," and therefore we bless "and commanded us." But a practice upon which we do not bless—as in Sukkah 44a regarding the willow on the seventh day—this is not included in rabbinic commandments. And here, when it says "why do we blow and sound while sitting…," it implies that this is only a practice, as the Ran explains regarding "why do we blow with a ram’s horn"—that the question is on a practice. And note that it is a practice and not a rabbinic enactment, for we do not find in the Mishnah or baraita that one blows twice, and we do not bless on the standing blasts even if one interrupted between sitting and standing. Thus it is only a practice, not included in "lo tasur," and therefore Tosafot did not want to answer like the Rashba.

This is essentially as I wrote above.

Tosafot’s Answer

In the end, Tosafot leave the question of how we blow. They ultimately resolve it thus:

One can say that Bal Tosif does not apply when performing one mitzvah twice. For example, if a kohen blesses and then blesses the same congregation again; or one takes the lulav and then takes it again; and similarly, one blows and then blows again; and regarding the gifts of the firstborn [animal], too: if he gives on one horn twice, this is not Bal Tosif.

They innovate that doing a mitzvah twice is not Bal Tosif. The prohibition of adding exists only where one adds a different element to the mitzvah.

(Parenthetically, it is usually understood that even at the conclusion, Tosafot maintain that the Sages themselves are also bound by Bal Tosif. But according to my suggestion above, perhaps not. Tosafot would agree that rabbinic enactments and decrees do not clash with Bal Tosif; their question concerned only nonbinding recommendations.)

The Assumption Behind the Answer: The Essence of "Bal Tosif"

Regarding Tosafot’s resolution itself, why should there be a difference between performing a mitzvah twice and adding a new detail to the elements mandated by the Torah? In both cases, we add something we are not obligated to do. What conception underlies Tosafot’s resolution?

I preface with the principle that "One who is exempt from a matter and performs it is called an ignoramus". This principle deals with someone who performs a mitzvah as written even though, for some reason, he is exempt. In such cases there is no Bal Tosif, because nothing is being added to the Torah; it is the performance of a mitzvah the Torah itself prescribed, not something new. The rule of Bal Tosif says something similar regarding one who performs a "mitzvah" that the Torah never commanded—hence no one is obligated in it. There it is clearly an addition to the Torah, and that is the prohibition of Bal Tosif.

Now we can better understand and define Tosafot’s answer. They assume that Bal Tosif addresses a change to the "Shulḥan Arukh"—i.e., a change to the law itself—not the doing of acts that are not obligatory. If one blows the shofar again, he has not changed the law, since shofar blowing is part of it; he is merely "exempt yet doing." Tosafot assume that Bal Tosif is a law in the object of Torah (the halakhic corpus)—the prohibition is to change the Torah—not in the person. Adding actions and performances when the law itself is not thereby changed is not Bal Tosif.

Accordingly, Tosafot would likely hold that Bal Tosif exists also with respect to a beit din that adds a commandment, not only for individuals. Indeed, in such a case, those who changed the Torah are the judges; thus the primary problem lies with them. Of course, one who follows their instruction also transgresses, for he is also effecting a change following them. Even when an individual adds a mitzvah on his own (not by order of a court), the focus of the prohibition is that he changed the law, not that he did an act he was not commanded to do.

All this assumes that when a beit din adds a different mitzvah than the Torah’s, they indeed transgress Bal Tosif according to Tosafot—as the common understanding of their view has it. But I already noted that this is highly implausible (hence my suggestion that perhaps they are speaking only about a nonbinding practice).

The Rashba’s View

In that same sugya on 16a, the Rashba too addresses Tosafot’s question. After laying out Tosafot’s answer, he writes that it does not seem correct and offers his own explanation:

It seems that there is no difficulty at all. They said there is Bal Tosif only where one adds on his own accord, such as a kohen who adds a blessing of his own; or one who intentionally sleeps in the sukkah on the eighth day as a mitzvah; or where it occurs by accident that one [wrongly] mixes a single application [of blood] with four applications, and the like. But where the Sages stood and instituted for a need, there is no Bal Tosif, for the Torah already said "according to the instruction that they teach you." And know that the eighth day of Sukkot in our times entails a rabbinic mitzvah to sleep and eat in the sukkah for the sake of the mitzvah, even though we are now expert in the calendar; and R. Yoḥanan proclaimed that where the messengers of Nisan arrive but those of Tishrei do not, one should observe two days—Nisan because of Tishrei. Thus, whenever needed, the beit din decrees and adds, and the authority is in their hands. Likewise with Bal Tigra when needed; for example, when Rosh Hashanah falls on Shabbat—even though the Torah said to blow, they arose and decreed not to blow, and all this is for need. Here, too, they saw a need to blow and blow again; and it is a mitzvah to heed the Sages’ words by "lo tasur." So it seems to me.

His claim is exactly as I argued against Tosafot’s question: the Sages are exempt from Bal Tosif. The Torah granted them authority to institute and decree; therefore, it is clear that their enactments and decrees do not constitute Bal Tosif—neither for the beit din nor for those who obey them.

From the Rashba we learn that, in his view, even performing a mitzvah twice is Bal Tosif; hence he resolves the difficulty differently. That is, for him the prohibition is about the person, not the legal object; the focus is on the individual who performs the mitzvah, not on the beit din who instituted it.

Rambam, in a similar vein, writes in Laws of Rebels 2:9:

Since a court has the authority to decree and prohibit something permitted—and its prohibition stands for generations—and it also has authority to permit biblical prohibitions ad hoc, what then did the Torah warn in "You shall not add to it and you shall not subtract from it"? This warns not to add to or subtract from the words of Torah and to establish a matter forever as if it were from the Torah, whether in the Written Torah or the Oral Torah. How so? The Torah says "Do not cook a kid in its mother’s milk." By tradition we learned that this text forbids cooking and eating meat with milk, whether beast or wild animal; but fowl meat with milk is permitted by the Torah. If a beit din were to permit wild animal meat with milk—that would be subtracting. And if they were to forbid fowl meat and say it is included in "kid" and is forbidden by the Torah—that would be adding. But if they were to say: Fowl meat is permitted by the Torah, and we forbid it, and we notify the people that this is a decree lest the matter lead to error and people say: since fowl is permitted because it was not specified, so too wild animal meat is permitted because it was not specified; and another might come and say: even domestic animal meat is permitted except for the goat; and another might say: even goat meat is permitted with cow’s or sheep’s milk, for it says "its mother," meaning its own kind; and another might say: even with the goat’s milk if it is not its own mother, for it says "its mother"—therefore we forbid all meat with milk, even fowl. This is not adding; it is making a fence for the Torah. And so with all similar cases. +/Raavad’s gloss/: Since the beit din has the authority to decree and prohibit…

Rambam here adds an important halakhic implication that the Rashba does not mention: in his view, the beit din is not entirely exempt from Bal Tosif. When they legislate, they must make it clear that their addition is rabbinic and not an addition to the Torah’s commandments; otherwise, they transgress Bal Tosif. Incidentally, here it seems that the beit din themselves transgress Bal Tosif, not just those who observe their enactment. This actually aligns more with Tosafot—that Bal Tosif is about the legal object (changing the Torah), not the person. Not for nothing is Rambam speaking here about enactments that fit Tosafot’s category of Bal Tosif (not repeating a mitzvah but creating a new one).

The Raavad there disputes Rambam:

Heaven forfend—these words are empty wind. Anything they decreed and prohibited as a fence and safeguard of the Torah does not involve Bal Tosif, even if they established it for generations and made it like Torah-law and supported it with a verse, as we find in many places—rabbinic law with mere scriptural asmakhta. And if they subtract for a temporary need, as Elijah on Mount Carmel, that too is by Torah law—"It is time to act for the Lord; they have voided Your Torah." You will not find a prohibition of adding except with positive commandments, such as lulav, tefillin, tzitzit, and the like—whether for a time, or for generations, whether they made it as Torah-law or did not.

He maintains, as per the Rashba, that beit din is entirely exempt from Bal Tosif, and from his words it appears there is no obligation upon them even to clarify that their enactment is rabbinic (otherwise, how does he differ from Rambam?!). This sharpens Rambam’s innovation relative to the Rashba and shows that although Rambam resolves Tosafot’s difficulty like the Rashba and not like Tosafot, his conception of Bal Tosif is closer to Tosafot (see also Minḥat Ḥinukh mitzvah 313, and Ritva here).

By the way, according to Rambam’s suggestion another way arises to resolve the above difficulties on Tosafot. It could be that Tosafot ask here because when the Gemara wonders why we blow and sound seated and standing, it reveals that the reason is unclear—implying that the Sages who instituted this did not clarify that it was rabbinic (had they clarified, the Gemara’s question would not have arisen). Perhaps that is why Tosafot ask specifically here why the beit din (primarily them, and less so the laypeople) do not transgress Bal Tosif. But if they had clarified, they would indeed not have transgressed; hence Tosafot do not ask about other enactments and decrees. However, their wording does not indicate this is their intent.

R. Akiva Eiger’s Remark

R. Akiva Eiger there raises an objection to Tosafot:

Tosafot s.v. "ve-tok‘in": We say in the chapter "Ra’uhu Beit Din"—I am dust under the feet of our masters, the Ba‘alei Tosafot, but in my poverty it is not comparable. There, if another congregation presents itself and he raises his hands to bless them, he is doing the mitzvah to bless them; therefore it is still considered the time of the mitzvah. But here, regarding shofar, even if he blows for another congregation, he is not performing a mitzvah, for he has already fulfilled his own; rather, he is merely discharging them—the congregation are the ones doing the mitzvah, and he is their agent to discharge them. Therefore, for him it is no longer the time of the mitzvah.

His claim is that in Birkat Kohanim, even after the kohen has blessed, if another congregation comes and he blesses them, he performs the mitzvah of Birkat Kohanim; therefore, even after blessing, it is still the time of the mitzvah. But with shofar, even if others come and he blows for them, the blower has no mitzvah (I think this is independent of whether the mitzvah is in blowing or in hearing). Therefore, Tosafot’s rejected resolution can stand: after one has blown, it is no longer the time of the mitzvah; therefore, even if one blows "to confound the Satan," there is no Bal Tosif because intent is lacking, and after the time one does not transgress without intent. This, of course, is according to Tosafot’s view that intent to fulfill a rabbinic enactment does not count as intent to add for Bal Tosif. See Responsa Ḥatam Sofer OḤ §167, where he sends R. Akiva Eiger his own reply (in my view unconvincing) and further discusses whether after fulfilling the mitzvah it is still considered its time.

The Ran’s View

The Ran on the Rif here in the sugya also brings Tosafot’s question and answer, but with a significant difference:

They asked in Tosafot: does he not transgress Bal Tosif? And if you say: since they have already discharged their obligation while sitting, it is not the time, and Rava concludes later in "Ra’uhu Beit Din" (28b) that to transgress when it is not the time requires intent—still this is not sufficient, for here too he intends a mitzvah and would transgress Bal Tosif. And they answered that Bal Tosif does not apply to doing a mitzvah twice. Likewise with Birkat Kohanim—even if they bless many times a day for congregations, this is not Bal Tosif unless he adds a blessing of his own, such as "May the God of your fathers add to you," and the like. And if one took the lulav and took it again in one day, or ate matzah and ate it again many times in one day, this is not Bal Tosif. And likewise offerings requiring a single application of blood: if he gave on that horn even a hundred times, there is no Bal Tosif. So too, if he blew and blew again even a hundred times in one day—even with intent for the mitzvah—there is no Bal Tosif.

On the face of it he understood exactly like Tosafot. But there is a difference in the formulation of the question: he assumes that after fulfilling the mitzvah it truly is no longer its time (unlike Tosafot, who prove from Birkat Kohanim that it is still its time). However, in his view, intent to fulfill a rabbinic enactment does count as intent for Bal Tosif; hence even if we say that after fulfillment it is no longer the time, he would still transgress Bal Tosif. That is, he disagrees with Tosafot on two points: (1) whether intent to fulfill a rabbinic enactment constitutes intent for Bal Tosif after the time; (2) whether after fulfilling the mitzvah it is still the time. In the end the difficulty remains, just as for Tosafot (he does not accept the Rashba’s premise that rabbinic enactments are categorically exempt from Bal Tosif), and then he brings Tosafot’s answer.

In Kehillot Ya‘akov here §15 it is proven like R. Akiva Eiger—that the Ran holds that even after fulfilling the mitzvah it is still the time of the mitzvah; this would seem difficult from Birkat Kohanim. We are therefore forced to say the Ran holds like R. Akiva Eiger: one cannot learn from Birkat Kohanim to shofar blowing (incidentally, in his ḥiddushim here the Ran asks exactly like Tosafot and seems fully to accept their approach).

Note that he understood that the case of Birkat Kohanim involves transgressing Bal Tosif because the kohen added a blessing of his own, not because he merely blessed again. Indeed, even according to Tosafot, we must explain it thus, for at their conclusion doing a mitzvah twice is not Bal Tosif at all; therefore, in Birkat Kohanim—even if it is still the time—there would be no Bal Tosif unless he added a new blessing. We are compelled to say that there the case is adding his own blessing, and not merely repeating.

Kehillot Ya‘akov’s Reading of Tosafot

We remain with R. Akiva Eiger’s question on Tosafot: how can they compare Birkat Kohanim to shofar blowing? As noted, that is why the Ran framed the question differently. The Kehillot Ya‘akov there proposes a resolution:

His claim is that, according to Tosafot, the prohibition of Bal Tosif is determined by the time in which the mitzvah is relevant, irrespective of whether the person performing it has a mitzvah or not. The time for Birkat Kohanim is the entire day; the indication is that if another congregation comes, he will bless them. Therefore it does not matter whether the one blessing fulfills a mitzvah personally; the scenario of another congregation is cited only as an indication that it is still the time of the mitzvah. Thus, shofar blowing too is relevant all day, for if another congregation comes he will blow for them. True, in that case the blower would have no personal mitzvah, but that is not important. The description "if another congregation comes" is cited only as evidence that the entire day is the time of the mitzvah.

The basis for Tosafot’s position seems to be that Bal Tosif is not a prohibition on performing an extra mitzvah, but on altering the law. Hence, the criterion for transgression is not whether the person is fulfilling a mitzvah but the definition of the mitzvah’s time itself. We look at the mitzvah’s parameters as such, and not at the one who performs it. In other words: Bal Tosif is determined by addition in the legal object (the mitzvah itself), not in the subject (the act of fulfillment). This fits very well with Tosafot’s conclusion above: Bal Tosif is about adding to the law, not about adding acts of fulfillment.

It should be noted, however, that the Ran apparently disputes Tosafot, since he holds like R. Akiva Eiger that the "time" for Bal Tosif is set according to the act of fulfillment (whether the person is doing a mitzvah) and not by the mitzvah’s objective time (the object). On the other hand, he accepts Tosafot’s conclusion that performing a mitzvah twice is not Bal Tosif—meaning that for him too Bal Tosif is about the legal object and not the subject. Perhaps, in the flow of his words, this itself is the resolution: in his question he understood Bal Tosif to be about the subject; therefore he did not compare shofar to Birkat Kohanim. And the answer is precisely that Bal Tosif is about the object (hence doing it twice is not Bal Tosif).

According to this, he could have answered differently as well: concede that Bal Tosif is about the subject (hence no analogy from Birkat Kohanim), and concede that doing a mitzvah twice is Bal Tosif (for the subject performs the mitzvah twice)—but after one has blown it is no longer the time, so he does not transgress. It seems he did not choose this because, in his view, intent for a rabbinic mitzvah is intent also for Bal Tosif, and therefore one would transgress even after the time.

May it be a good year for us all. Good tidings and success for the community and the individual. And may the verse be fulfilled for us speedily: "And the redeemed of the Lord shall return and come to Zion with song."