Mishneh Torah, Negative Mitzvot 246-365

Sugya Map

The text snippet under analysis introduces a pivotal discussion within the Rambam's enumeration of negative commandments, specifically concerning the prohibition of incestuous relations with one's daughter (לֹא לִבְעֹל אֶת בִּתּוֹ). While the Torah explicitly forbids relations with one's granddaughter (daughter's daughter or son's daughter), it conspicuously omits a direct prohibition against relations with one's daughter. The Rambam categorizes this prohibition as mid'Oraita (Biblical), despite its non-explicit nature, relying on an oral tradition and a logical inference (Kal V'Chomer). This immediately raises fundamental questions regarding the nature of Torah Sheba'al Peh (Oral Law) and its relationship to Torah Shebichtav (Written Law), particularly the authoritative weight of hermeneutical principles.

Issue

The core issue is the mid'Oraita status of a prohibition (bat, daughter) that is not explicitly stated in the Torah Shebichtav, but is derived via Kal V'Chomer (a fortiori) from a less severe, explicitly stated prohibition (bat bat, granddaughter), and the Rambam's justification for this classification.

Nafka Mina(s)

1. Nature of Mid'Oraita Derivations: Does a Kal V'Chomer yield a mid'Oraita prohibition with full chiyuv karet (divine excision) and other Torah penalties, or is it merely an asmachta (support) for a Rabbinic decree? This is the locus of the Rambam-Ramban debate.
2. Rambam's Counting Methodology: How does this instance align with Rambam's Shoresh Sheni (Second Principle) in Sefer HaMitzvot, where he delineates the criteria for including mitzvot in the 613? Specifically, his assertion that mitzvot derived through the 13 hermeneutical principles are mid'Oraita.
3. The Concept of Davar HaYadu'a / Lo Tzricha Lemiktav: Is the prohibition of bat so inherently obvious or universally understood that the Torah deemed it unnecessary to state explicitly, despite its severity?
4. Application to other Arayot: Does this analytical framework extend to other arayot where a prohibition might be derived rather than explicitly stated? (e.g., father-in-law's mother, as noted by some commentators).

Primary Sources

• Mishneh Torah, Negative Mitzvot 334-336: The immediate text.
• Leviticus 18:10: The explicit source for bat bat.
• Sifra, Acharei Mot, Parasha 10, Chapter 5: The Tannaitic source for the Kal V'Chomer.
• Rambam, Sefer HaMitzvot, Shoresh Sheni: Rambam's foundational principles for counting mitzvot.
• Ramban, Hassagot L'Sefer HaMitzvot, Shoresh Sheni: Ramban's critique of Rambam's methodology.
• Kesef Mishneh, Hilchot Issurei Bi'ah 1:6: Commentary on Rambam's position.
• Shulchan Aruch, Even Ha'Ezer 15:1: Halachic codification of the prohibition.

Text Snapshot

The relevant lines from the Mishneh Torah, Negative Mitzvot, are:

Not to have intimate relations with one's son's daughter, as [Leviticus 18:10] states: "[Do not commit] incest with your son's daughter."^1 Not to have intimate relations with one's daughter's daughter, as [Leviticus, ibid.] continues: "...and do not commit incest with your daughter's daughter."^2 Not to have intimate relations with one's daughter. Why was this prohibition not explicitly stated in the Torah? Since the Torah forbade [relations with] one's daughter's daughter, it did not mention [the prohibition against relations with] one's daughter. [Nevertheless, according to the oral tradition, the prohibition against [relations with] one's daughter has the status of a Torah law like the other sexual offences [and is not considered as Rabbinic in origin].^3

Dikduk/Leshon Nuance

The Rambam's leshon (language) is highly precise and demands careful scrutiny.

1. "Why was this prohibition not explicitly stated in the Torah?" (לָמָּה לֹא נֶאֶמְרָה בַּת בְּפֵרוּשׁ בַּתּוֹרָה?) This rhetorical question directly addresses the apparent lacuna, signaling that the Rambam is about to provide a deeper explanation beyond mere omission. It implies that the absence of explicit mention is not an oversight but deliberate.
2. "Since the Torah forbade [relations with] one's daughter's daughter, it did not mention [the prohibition against relations with] one's daughter." (וְהוֹאִיל וְאָסַר בַּת בִּתּוֹ, לֹא הִזְכִּיר בַּתּוֹ.) This is the crux of the Rambam's logical derivation. It posits that the explicit prohibition of bat bat (granddaughter) renders the explicit prohibition of bat (daughter) superfluous, due to the inherent Kal V'Chomer. The chomer (more stringent case) is explicitly stated, implying the kal (less stringent, or more obvious case).
3. "[Nevertheless,] according to the oral tradition, the prohibition against [relations with] one's daughter has the status of a Torah law..." (אֶלָּא מִפִּי הַשְּׁמוּעָה לָמַדְנוּ שֶׁאֲסוּרָה מִן הַתּוֹרָה...). The phrase "מִפִּי הַשְּׁמוּעָה" (from the mouth of tradition) is critical. It implies a masoret (received tradition) that legitimizes the Kal V'Chomer as a mid'Oraita derivation, distinguishing it from purely Rabbinic asmachta. This tradition is not merely a logical inference but a received interpretive key that unlocks the Torah's intent. The Rambam here subtly reinforces his Shoresh Sheni position, where certain derivations by Midot ShehaTorah Nidreshet Bahem (hermeneutical principles) are considered guf haTorah (the body of the Torah) when supported by tradition.

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^1. Mishneh Torah, Negative Mitzvot 334. ^2. Mishneh Torah, Negative Mitzvot 335. ^3. Mishneh Torah, Negative Mitzvot 336.

Readings

The Rambam's seemingly straightforward presentation regarding the prohibition of bat (daughter) belies a profound and longstanding debate among Rishonim and Acharonim concerning the very definition of a mitzvat lo ta'aseh mid'Oraita (Biblical negative commandment) and the authoritative scope of the Oral Law. Our analysis will focus on this foundational dispute, particularly between the Rambam and the Ramban, and the underlying Tannaitic source.

1. The Sifra: The Tannaitic Foundation

The primary Tannaitic source for the prohibition of bat is found in the Sifra on Acharei Mot:

מִנַּיִן אִם אָסַר בִּתּוֹ, שֶׁאַף בַּת בִּתּוֹ אֲסוּרָה? אֵינוֹ דִּין שֶׁבַּת בִּתּוֹ מִבַּתּוֹ לֹא קַל וָחֹמֶר הִיא?^4 "From where [do we know] that if He forbade his daughter, that even his daughter's daughter is forbidden? Is it not logical that his daughter's daughter from his daughter is a Kal V'Chomer?"

At first glance, the Sifra's formulation appears to be the inverse of the Rambam's. The Sifra begins with the premise that bat (daughter) is forbidden ("אם אסר בתו"), and then uses a Kal V'Chomer to derive the prohibition of bat bat (granddaughter). The Rambam, however, states that bat bat is explicitly forbidden (Lev. 18:10) and then explains why bat is not explicitly mentioned, implying bat is derived from bat bat.

The Sifra continues by rejecting this Kal V'Chomer:

תַּלְמוּד לוֹמַר: "בַּת בִּנְךָ וּבַת בִּתְּךָ לֹא תִקַּח לְגַלּוֹת עֶרְוָתָהּ". לָמַדְנוּ שֶׁבַּת בִּנְךָ וּבַת בִּתְּךָ אֲסוּרוֹת, אֲבָל בַּתּוֹ מֻתֶּרֶת? אֵינוֹ דִּין הוּא: וּמַה בַּת בִּתּוֹ שֶׁאֵינָהּ כְּמוֹתוֹ אֲסוּרָה, בַּתּוֹ שֶׁהִיא כְּמוֹתוֹ אֵינוֹ דִּין שֶׁתְּהֵא אֲסוּרָה?^5 "The verse states: 'Your son's daughter and your daughter's daughter, you shall not take to uncover her nakedness' (Lev. 18:10). We have learned that your son's daughter and your daughter's daughter are forbidden. But is his daughter permitted? Is it not logical: if his daughter's daughter, who is not like him [i.e., less closely related], is forbidden, his daughter, who is like him [i.e., directly from him], is it not logical that she should be forbidden?"

The Sifra's initial Kal V'Chomer (deriving bat bat from bat) is rejected because a verse explicitly prohibits bat bat. This rejection is a classic example of "אין אדם דן קל וחומר במקום שנאמר בו מפורש" (one does not derive a Kal V'Chomer in a place where it is explicitly stated). The Sifra then proceeds to ask: if bat bat is forbidden, does that imply bat is permitted? And then it presents the Kal V'Chomer that aligns with the Rambam's logic: if bat bat (less severe relationship) is forbidden, certainly bat (more severe relationship) is forbidden. This second Kal V'Chomer is not explicitly rejected by a verse, thus establishing the mid'Oraita prohibition of bat.

2. Rambam: Kal V'Chomer as Guf HaTorah with Masoret

The Rambam, in Sefer HaMitzvot, Shoresh Sheni, lays out his criteria for counting the 613 mitzvot. He unequivocally states that mitzvot derived through one of the 13 hermeneutical principles (כגון קל וחומר, גזירה שוה, בנין אב, וכל שאר המדות) are to be considered mid'Oraita, provided they are established by masoret (oral tradition):

"כל מצוה שתהיה גלויה מן התורה באחד מדרכי הלימוד שהתורה נדרשת בהן, כגון קל וחומר או גזירה שוה או בנין אב וכל שאר המדות – ואפילו היתה ההלכה ההיא דברי סופרים באמת, אבל יש לה סמך מן התורה באחד מדרכי הלימוד – אנו מונים אותה מן המצוות. וכל מצוה שאין לה סמך מן התורה אלא היא דברי סופרים לבד – אין אנו מונים אותה."^6 "Any mitzvah that is revealed from the Torah through one of the methods of exegesis by which the Torah is interpreted, such as Kal V'Chomer, Gezeirah Shavah, Binyan Av, and all other principles – even if that halacha were truly Rabbinic, but it has support from the Torah through one of the methods of exegesis – we count it among the mitzvot. But any mitzvah that has no support from the Torah except that it is solely Rabbinic – we do not count it."

The Rambam clarifies that a Kal V'Chomer is not merely an asmachta (support for a Rabbinic decree) but can be guf haTorah (the body of the Torah itself) if the masoret confirms that the Torah intended that derivation. The masoret ensures that the Kal V'Chomer is not a mere human logical inference but a divinely intended textual implication.

Thus, for the Rambam, the prohibition of bat is mid'Oraita because:

1. There is an explicit prohibition of bat bat (granddaughter) in Leviticus 18:10.
2. A Kal V'Chomer logically dictates that if the less proximate relationship (bat bat) is forbidden, the more proximate and foundational relationship (bat) must certainly be forbidden.
3. The "oral tradition" (mipi hashmuah) confirms that this Kal V'Chomer is guf haTorah and not a mere Rabbinic interpretation. The Sifra provides this masoret, confirming the Kal V'Chomer that bat is forbidden. The Rambam in MT 336 directly echoes this logic, stating that since bat bat is forbidden, it was unnecessary to explicitly state bat. The mipi hashmuah ensures that this lo tzarich lemiktav (no need to write) is rooted in a mid'Oraita inference.

3. Ramban: Kal V'Chomer as Asmachta or Mishna DeRabbanan

The Ramban, in his Hassagot (critique) on Sefer HaMitzvot, Shoresh Sheni, vehemently disagrees with the Rambam's expansive view of Kal V'Chomer and other hermeneutical derivations as mid'Oraita. For the Ramban, only explicit verses or halachot directly received from Sinai (halacha leMoshe miSinai), or gezeirah shavah (with a specific masoret for its application), can be considered mid'Oraita. A Kal V'Chomer, in his view, is a logical inference made by the Sages, and while its conclusion might be mid'Oraita (due to halacha leMoshe miSinai or other factors), the derivation itself is Rabbinic in nature, serving as an asmachta or a mishna deRabbanan.

The Ramban argues:

"אבל קל וחומר וגזירה שוה ובנין אב וכל שאר המדות, אע"פ שכל הנלמד מהן כאילו נאמר בפירוש בתורה, אינן מן המצוות אשר נמנה אותן. כי התורה לא באה ללמד אלא דברים שיש בהן חידוש, ואין התורה נותנת חיוב אלא בדברים שבאו בפירוש או בהלכה למשה מסיני שהיא כפירוש. ואם כן, כל מה שנלמד מן המדות הללו, אינו אלא סמך לדברי סופרים, ואינו מן המצוות שהן גוף התורה."^7 "But Kal V'Chomer, Gezeirah Shavah, Binyan Av, and all other principles, even though all that is learned from them is as if it were stated explicitly in the Torah, are not among the mitzvot that we count. For the Torah only came to teach novelties, and the Torah does not impose an obligation except on matters that are stated explicitly or by Halacha LeMoshe MiSinai, which is like an explicit statement. And if so, everything learned from these principles is merely a support for the words of the Sages, and is not among the mitzvot that are the body of the Torah."

The Ramban's position hinges on the idea that the Torah's purpose is to reveal new obligations, not to state the obvious or to rely solely on human logic for fundamental prohibitions carrying karet. If a Kal V'Chomer leads to a halacha that is indeed mid'Oraita, it is because that halacha itself is Halacha LeMoshe MiSinai, and the Kal V'Chomer merely provides a hint or a logical support for it.

Regarding bat, the Ramban would agree that it is mid'Oraita and incurs karet. However, he would attribute this status not to the Kal V'Chomer per se, but to a received Halacha LeMoshe MiSinai that bat is forbidden. The Kal V'Chomer in the Sifra then serves to explain why it wasn't explicitly written, or to offer a logical asmachta to this ancient tradition. The "oral tradition" the Rambam refers to would, for the Ramban, be the Halacha LeMoshe MiSinai itself, not merely the masoret confirming a Kal V'Chomer as mid'Oraita.

4. Kesef Mishneh: Reconciling the Sifra and Rambam

The Kesef Mishneh on Hilchot Issurei Bi'ah 1:6 directly addresses the Rambam's statement in Mishneh Torah 336 and the apparent discrepancy with the Sifra:

"כתב הרמב"ם בפרק א' מהלכות איסורי ביאה: 'ואסור אדם בבתו מן התורה, אף על פי שלא נאמר בה בפירוש, אלא קל וחומר הוא'. וכתב שם: 'למה לא נאמרה בת בפירוש בתורה? מפני שהיא ערוה חמורה מבת בתו, שהרי היא מגופו ממש, ואין צורך להזכירה, שהרי אם בת בתו אסורה, כל שכן בתו'. והוא לשון הספרא."^8 "The Rambam wrote in Chapter 1 of Hilchot Issurei Bi'ah: 'A man is forbidden to his daughter mid'Oraita, even though it is not explicitly stated concerning her, but it is a Kal V'Chomer.' And he wrote there: 'Why was bat not explicitly stated in the Torah? Because she is a ervah more severe than his daughter's daughter, for she is from his very body, and there is no need to mention her, for if his daughter's daughter is forbidden, certainly his daughter [is forbidden].' This is the language of the Sifra."

The Kesef Mishneh affirms that the Rambam's reasoning in Mishneh Torah (and Hilchot Issurei Bi'ah) is precisely that of the Sifra's second Kal V'Chomer. The Kesef Mishneh effectively resolves the apparent inversion: the Sifra's initial query "אם אסר בתו" is not a statement of fact but a hypothetical starting point to demonstrate the Kal V'Chomer that bat bat should be forbidden. Once that Kal V'Chomer is rejected due to the explicit verse (Lev. 18:10), the Sifra then reverses the logic, applying the Kal V'Chomer to derive bat from the now-explicitly forbidden bat bat.

The Kesef Mishneh further explains that the Rambam's "oral tradition" refers to the masoret that this particular Kal V'Chomer (from bat bat to bat) is indeed a mid'Oraita derivation, carrying the full weight of Torah law, including karet. This masoret is crucial, as not all Kal V'Chomers are deemed mid'Oraita in this manner. It's the oral tradition that informs us which hermeneutical derivations are guf haTorah.

In essence, the Kesef Mishneh supports the Rambam's interpretation: the prohibition of bat is so obvious and severe that the Torah only needed to state the chomer (granddaughter) to imply the kal (daughter), and the mipi hashmuah confirms that this is a legitimate mid'Oraita derivation, not merely a logical human inference.

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^4. Sifra, Acharei Mot, Parasha 10, Chapter 5 (Malbim ed., 18b). ^5. Sifra, Acharei Mot, Parasha 10, Chapter 5 (Malbim ed., 18b). ^6. Rambam, Sefer HaMitzvot, Shoresh Sheni. ^7. Ramban, Hassagot L'Sefer HaMitzvot, Shoresh Sheni. ^8. Kesef Mishneh, Hilchot Issurei Bi'ah 1:6.

Friction

The sugya of bat (daughter) stands at a critical juncture of lomdus, illuminating a fundamental tension between rational deduction and received tradition in defining the scope of Torah Shebichtav (Written Torah) and Torah Sheba'al Peh (Oral Torah). The Rambam's formulation in Negative Mitzvot 336 and Hilchot Issurei Bi'ah 1:6 sparks a profound kushya (difficulty), primarily in light of the Ramban's critique and the nuanced reading of the Sifra.

The Strongest Kushya: The Nature of Kal V'Chomer and Karet

The most potent kushya against the Rambam's position, as articulated by the Ramban, revolves around the authoritative status of Kal V'Chomer (a fortiori) as a source for a mitzvat lo ta'aseh mid'Oraita (Biblical negative commandment) that incurs karet (divine excision).

1. Ramban's Challenge to Kal V'Chomer as Guf HaTorah: The Ramban argues that Kal V'Chomer is merely a logical inference, a tool of human reason, not a direct divine utterance.^9 While it can lead to a halacha (law) that is mid'Oraita, the source of that halacha is not the Kal V'Chomer itself, but rather a Halacha LeMoshe MiSinai (law given to Moses at Sinai) that the Kal V'Chomer might logically support or explain. If Kal V'Chomer were truly guf haTorah, then every logically sound Kal V'Chomer should yield a mid'Oraita obligation, which is not the case in Halacha. The Ramban holds that the Torah only imposes chiyuv karet for prohibitions that are explicitly stated or are Halacha LeMoshe MiSinai that functions k'fi perush (like an explicit statement). To say that a Kal V'Chomer alone can generate a karet offense seems to elevate human reasoning to the level of divine pronouncement, which for Ramban, undermines the unique authority of Torah Shebichtav and the masoret of Halacha LeMoshe MiSinai that defines mid'Oraita.

2. The "Oral Tradition" (מִפִּי הַשְּׁמוּעָה): The Rambam's phrase "אֶלָּא מִפִּי הַשְּׁמוּעָה לָמַדְנוּ שֶׁאֲסוּרָה מִן הַתּוֹרָה" (but from the mouth of tradition we learned that it is forbidden from the Torah) attempts to bridge this gap. However, the Ramban would retort: What is this "oral tradition"? Is it a tradition that Kal V'Chomer is mid'Oraita here, or is it a tradition that the halacha itself is mid'Oraita (i.e., a Halacha LeMoshe MiSinai) for which the Kal V'Chomer is merely an asmachta? If it's the latter, then the Kal V'Chomer is not the source of the mid'Oraita status, but rather a logical explanation for an already existing mid'Oraita law. The Rambam's language, "Since the Torah forbade [relations with] one's daughter's daughter, it did not mention [the prohibition against relations with] one's daughter," strongly implies the Kal V'Chomer is the reason for the omission and the source of the prohibition. This is precisely what the Ramban contests.

3. The Sifra's Rejection of Kal V'Chomer: The Sifra itself, in its initial discussion, rejects a Kal V'Chomer when an explicit verse is available. While it then employs a second Kal V'Chomer to derive bat from bat bat, the very act of rejecting an earlier Kal V'Chomer for its lack of explicit textual support (or redundancy with explicit text) suggests a cautious approach to such derivations. This might support the Ramban's view that Kal V'Chomer is not inherently guf haTorah but a tool to be used judiciously, and often an asmachta. If Kal V'Chomer was always guf haTorah, why would the Sifra engage in such a back-and-forth, seemingly testing its limits?

The Best Terutz (or two): Reconciling Rambam and Sifra, and the Role of Masoret

To address these kushyot, we must delve deeper into the Rambam's understanding of Kal V'Chomer and the crucial role of masoret.

Terutz 1: The Kal V'Chomer as a "Revealed" Truth, Confirmed by Masoret

The Rambam's position is not that any logical Kal V'Chomer generates mid'Oraita status. Rather, it is specifically when the Chazal (Sages) transmit a masoret that a certain Kal V'Chomer derivation is indeed the intended meaning of the Torah, making it guf haTorah. This is the core of Shoresh Sheni.

1. Not Just Human Logic, but Divine Intent: For the Rambam, the 13 Midot are not mere human hermeneutical tools applied to the text post-factum. Instead, they are the very divine methodology by which the Torah's meaning is "revealed" or "uncovered." When the Torah says "Thou shalt not eat blood," and Chazal derive via Kal V'Chomer that one should not eat a limb from a living animal (אבר מן החי), the Kal V'Chomer is not just a human logical leap. It is the designated way the Torah communicates that particular prohibition. The "oral tradition" is the masoret that this specific Kal V'Chomer is one such divinely intended revelation. It tells us which Kal V'Chomers are guf haTorah and which are asmachtot. Thus, karet is incurred because the Kal V'Chomer, in this context, is effectively a divine statement.

2. Sifra's Pedagogy: The Sifra's initial rejection of the Kal V'Chomer (deriving bat bat from bat) can be understood as a pedagogical device. It teaches the principle that explicit verses override logical derivations. However, once bat bat is explicitly established, the Sifra then proceeds to the Kal V'Chomer that bat is forbidden from bat bat. This second Kal V'Chomer is presented not as a rejected or debatable inference, but as a universally accepted truth, confirmed by the masoret. The Sifra's role here is to demonstrate how this received truth is rooted in the text, not to create the halacha itself through novel reasoning. The mipi hashmuah (oral tradition) confirms that this Kal V'Chomer is the Torah's way of communicating the prohibition of bat. The Sifra is thus presenting the masoret of how to read the text.

3. The Severity of Bat: The Rambam's explanation that bat is "ערוה חמורה מבת בתו, שהרי היא מגופו ממש" (a more severe ervah than his daughter's daughter, for she is from his very body) further solidifies this approach.^10 The obviousness of the prohibition of bat is so great that the Torah chose to implicitly convey it through the Kal V'Chomer from bat bat, rather than explicitly stating it. It's a case of lo tzarich lemiktav (no need to write explicitly) because the principle is so self-evident (and confirmed by tradition). The Torah, in its wisdom, often omits the obvious to emphasize the less obvious, or to teach principles of derivation.

Terutz 2: The Practical Consensus and the Weight of Karet

While the theoretical debate between Rambam and Ramban regarding the source of mid'Oraita status for Kal V'Chomer is profound, it is crucial to note that both agree on the halachic outcome: the prohibition of bat is mid'Oraita and incurs karet. The dispute is not about the halacha itself, but its hermeneutical genesis.

1. The Authority of Chazal: The Terutz can also lean on the undisputed authority of Chazal to define Torah Sheba'al Peh. Even if the Ramban views Kal V'Chomer as a Rabbinic interpretive tool, when Chazal unanimously declare a halacha derived through it to be mid'Oraita and subject to karet, that declaration carries inherent weight. It becomes part of the received masoret which defines the mid'Oraita category. The mipi hashmuah in the Rambam thus refers to this collective, undisputed tradition of Chazal that bat is mid'Oraita and derived in this manner.

2. The Function of Asmachta: Even for the Ramban, an asmachta is not meaningless. It shows that Chazal's halachot are not arbitrary but are rooted in the Torah Shebichtav. When an asmachta supports a Halacha LeMoshe MiSinai, it demonstrates the harmony between the Written and Oral Torah. In the case of bat, the Kal V'Chomer can be seen as the asmachta for the Halacha LeMoshe MiSinai of bat, thus providing a textual basis for its mid'Oraita status.

In conclusion, the Rambam's formulation, when understood through the lens of Shoresh Sheni and the Kesef Mishneh's explanation of the Sifra, presents a coherent system where Kal V'Chomer, guided by masoret, serves as a legitimate and divinely intended method for revealing mid'Oraita prohibitions, even those incurring karet. The kushya highlights the fundamental divergence in philosophical approach to Torah Sheba'al Peh between the Rambam and Ramban, but the terutzim demonstrate the Rambam's consistent internal logic.

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^9. Ramban, Hassagot L'Sefer HaMitzvot, Shoresh Sheni. ^10. Mishneh Torah, Hilchot Issurei Bi'ah 1:6.

Intertext

The sugya of bat and its Kal V'Chomer derivation resonates with broader themes in Halacha and Aggadah, particularly concerning the nature of implied prohibitions, the role of sevara (logic) in halachic discourse, and the scope of Torah Sheba'al Peh.

1. Other Arayot Derived by Kal V'Chomer / Lo Tzarich Lemiktav

The prohibition of bat is not unique in its non-explicit mid'Oraita status among the arayot. Other relationships are also derived through similar means, reinforcing the notion that the Torah does not always explicitly state every prohibition, particularly when it can be logically inferred from related verses or is deemed self-evident.

• Father-in-law's Mother (אֵשֶׁת חָמִיו): The Gemara in Yevamot discusses the prohibition of a father-in-law's mother (i.e., wife's grandmother). While the Torah explicitly forbids a wife's mother (חֲמוֹתְךָ), it does not explicitly forbid the wife's grandmother. Rashi (on Yevamot 21b s.v. דאיתקש) and other Rishonim explain that this too is derived by Kal V'Chomer or is considered a davar ha'yadu'a (a known matter, a logical extension of the prohibition of chamotcha). The Rambam himself lists the prohibition of "wife's mother's mother" and "wife's father's mother" as mid'Oraita in Hilchot Issurei Bi'ah 1:9, and the Kesef Mishneh there notes that these are derived from the explicit prohibition of chamotcha via Kal V'Chomer or biniyan av (a hermeneutical principle of deriving from one or two verses). This demonstrates a consistent methodology in the Rambam where such derivations, when supported by masoret, yield mid'Oraita prohibitions. The severity of arayot demands that even implied prohibitions carry full Torah weight.

• Eiver Min HaChai (Limb from a Living Animal): The prohibition against eating a limb from a living animal is often cited as a prime example of a Kal V'Chomer that yields a mid'Oraita law. The Torah explicitly forbids eating blood (דָּם לֹא תֹאכֵלוּ)^11 and neveila (carrion), which implies the animal is dead. The Kal V'Chomer is: if one may not eat the blood, which is a mere fluid, certainly one may not eat a limb, which is a substantial part of the living creature.^12 While the prohibition itself is ancient, the Kal V'Chomer provides a textual anchor. The Rambam counts eiver min hachai as Negative Mitzvah 183 and attributes its mid'Oraita status to a derivation. This parallel reinforces his view that fundamental prohibitions can be derived, not just explicitly stated.

2. The Principle of Davar HaYadu'a / Lo Tzarich Lemiktav

The Rambam's explanation for the omission of bat — "Since the Torah forbade [relations with] one's daughter's daughter, it did not mention [the prohibition against relations with] one's daughter" — is an application of the principle of davar ha'yadu'a or lo tzarich lemiktav. This idea, that the Torah omits what is self-evident or logically derivable from what is stated, is a recurring theme in Chazal.

• The Mitzvah of Lo Titgodedu (Not to Make Incisions): Deuteronomy 14:1 states, "You shall not cut yourselves, nor make any baldness between your eyes for the dead." The Gemara in Makkot 21a discusses the prohibition of gedidah (cutting oneself for the dead). The verse says "לא תתגודדו" in a general sense. The Rambam counts "Not to make cuts in our flesh, as the worshipers of false gods do" (Negative Mitzvah 287) and "Not to tear out hair [in mourning] for the dead" (Negative Mitzvah 329). The Sifrei Devarim 96 explains that the prohibition is so obvious that it applies even without explicit mention for every specific instance. The Torah often sets a principle, and the details are known through Torah Sheba'al Peh. The Rambam's explanation for bat fits this pattern: the severity of the relationship with a daughter is so obvious that the Torah didn't need to state it explicitly; the prohibition of the granddaughter suffices to establish the principle through Kal V'Chomer.

• The "Obvious" Status of God's Existence: In a different vein, the Rambam, in Hilchot Yesodei HaTorah 1:1, states that the belief in God's existence is the first positive commandment. Yet, the Torah does not explicitly command "Believe in God." The Rambam views this as a davar ha'yadu'a that is so fundamental it doesn't require an explicit command. While not a Kal V'Chomer per se, it shares the characteristic of a fundamental truth that the Torah assumes rather than states directly. The very first negative commandment, "not to consider the thought that there is another divinity aside from God" (Negative Mitzvah 246), is explicit, but the positive command to believe is not. This showcases the Torah's selective explicitness.

3. Responsa Literature on Derivations and Karet

The debate between Rambam and Ramban regarding the mid'Oraita status of Kal V'Chomer derivations has practical implications that occasionally surface in responsa literature, especially concerning the imposition of severe penalties.

• The Chazon Ish on Issurei Bi'ah: The Chazon Ish (Even Ha'Ezer 23:14) delves into the nuances of arayot derived through drasha (exegesis). He explores instances where Chazal derive prohibitions with karet via gezeirah shavah or other midot. He generally aligns more with the Rambam's view that when Chazal establish a derivation as mid'Oraita, it carries full Torah weight. His rigorous analysis of the logical and traditional underpinnings of arayot prohibitions, often involving complex textual inferences, highlights the centrality of Torah Sheba'al Peh in defining even the most severe mid'Oraita laws, even when they are not explicit. The Chazon Ish emphasizes that the masoret is the ultimate arbiter, validating the interpretive mechanism as divinely intended.

These intertextual connections demonstrate that the unique case of bat is not an isolated anomaly but rather an illustration of a broader halachic principle: the Written Torah, interpreted through the lens of the Oral Tradition and its divinely sanctioned hermeneutical tools, yields a comprehensive and rigorous legal system that extends beyond explicit textual statements. The Rambam's approach, while challenging, provides a consistent framework for understanding this intricate relationship.

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^11. Leviticus 7:26. ^12. Sanhedrin 59a; Rambam, Hilchot Ma'achalot Asurot 5:1.

Psak/Practice

The theoretical machloket (dispute) between the Rambam and Ramban regarding the precise mechanism by which the prohibition of bat (daughter) attains its mid'Oraita status does not, in fact, result in any practical nafka mina (halachic difference) in terms of the psak (ruling) itself. All poskim (halachic decisors), without exception, agree that relations with one's daughter are unequivocally forbidden mid'Oraita and incur the penalty of karet.

1. Unanimous Halachic Status: Mid'Oraita and Karet

The Shulchan Aruch, the foundational codification of Halacha, states explicitly:

אֵלּוּ הֵן עֲרָיוֹת הָאֲסוּרוֹת מִן הַתּוֹרָה וְחַיָּבִין עֲלֵיהֶם כָּרֵת... בִּתּוֹ...^13 "These are the forbidden arayot that are forbidden mid'Oraita and for which one is liable for karet... his daughter..."

This enumeration, without qualification regarding the derivation method, reflects the consensus among poskim. The Beit Yosef and later Acharonim on the Shulchan Aruch discuss the Rambam-Ramban debate but ultimately affirm the practical outcome. The machloket is thus l'shma (for the sake of heaven), a deep intellectual discourse about the nature of Torah, rather than a disagreement leading to different practical rulings.

2. Meta-Psak Heuristics: Understanding the Scope of Torah Sheba'al Peh

While not impacting the specific halacha of bat, this sugya is immensely significant for meta-psak heuristics — the underlying principles and methodologies that inform halachic decision-making and the understanding of the mesorah (tradition).

• Rambam's Rigorous Categorization: The Rambam's insistence on classifying Kal V'Chomer and other midot (hermeneutical principles) as capable of yielding mid'Oraita law (when supported by masoret) provides a robust framework for understanding the comprehensive nature of Torah Sheba'al Peh. For the Rambam, the Oral Law is not merely a set of Rabbinic interpretations or enactments, but rather the divinely intended key to unlocking the full breadth and depth of the Written Torah. This perspective implies that a posek must be intimately familiar not only with explicit verses but also with the hermeneutical pathways that Chazal received to discern the Torah's complete legal system.

• Ramban's Emphasis on Masorah: The Ramban's counter-argument, while differing on the source of the mid'Oraita status, equally emphasizes the centrality of masorah. For him, if a Kal V'Chomer yields a mid'Oraita law, it is because that law itself is a Halacha LeMoshe MiSinai, a direct tradition from Sinai. This view underscores the importance of mesorah as the primary determinant of mid'Oraita law, even over seemingly compelling logical inferences. It cautions against overly relying on human reason alone to define Biblical obligations.

• The Role of Sifra: The Sifra's intricate discussion serves as a powerful testament to the origins of Halacha. It demonstrates that even fundamental prohibitions were subjected to rigorous textual and logical analysis by Chazal, who then transmitted the authoritative interpretation. This highlights the dynamic and analytical nature of Torah Sheba'al Peh development, even while remaining anchored in masorah.

In practice, this sugya teaches us that the mesorah is paramount. Whether one follows the Rambam's understanding of Kal V'Chomer as guf haTorah or the Ramban's view of it as asmachta for Halacha LeMoshe MiSinai, the ultimate arbiter is the received tradition of Chazal regarding which laws are mid'Oraita and which are derabanan. The debate is a fascinating window into the metzuyaut (reality) of Torah, where divine revelation intertwines with human intellect, all guided by an unbroken chain of tradition.

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^13. Shulchan Aruch, Even Ha'Ezer 15:1.

Takeaway

This sugya profoundly illustrates that Torah Sheba'al Peh is not merely an addendum to the Written Law, but its indispensable interpretive key, revealing mid'Oraita prohibitions even when the text is silent. The debate between Rambam and Ramban regarding Kal V'Chomer derivations underscores the critical role of masoret in defining the scope of Biblical law and the nature of divine revelation.