Halakhah su Deuteronomio 24:5

The Gemara seeks to discover a concrete halakhic application, as distinct from a purely semantic difference, of the issue that divides the Sages and R. Judah. A practical difference arising from their controversy is found by the Gemara in the application of a general principle that provides that a person engaged in performance of a mizvah is exempt from the fulfillment of other commandments. R. Judah considers the waging of preemptive war to constitute fulfillment of a mizvah; hence, according to R. Judah, combatants are exempt from fulfilling other commandments while engaged in military duties associated with preemptive war. The Sages regard such incursions as discretionary in nature and hence regard soldiers engaged in such battles as being fully obligated with regard to the fulfillment of other commandments.³The text of the Gemara reads as follows:
The Gemara does not tell us explicitly whether it is R. Judah or the Sages who consider war “to diminish the heathens” to constitute a commanded war. Rashi and Rambam, in their respective commentaries, explain that R. Judah deems such war to be commanded while the Sages consider such war to be discretionary. (The interpretation of these authorities have been followed in the parenthetical interpretations within the translation above.) Indeed, Rashi’s interpretation is taken directly from the words of R. Yoḥanan: [A war which is designated] as permitted by the Sages is identical with [war which is designated as] commanded by R. Judah, i.e., there is a category of war which is deemed to be “commanded” by R. Judah while, according to the Sages, the identical war is merely “discretionary.” The war in question is then identified by Rava as war “to diminish the heathens so that they shall not march against them.” Thus there is no dispute between Rava and R. Yoḥanan; Rava merely amplifies the statement of R. Yoḥanan. According to both, the dispute between the Sages and R. Judah is with regard to whether participants in a war “to diminish the heathens” are exempt from fulfillment of other precepts. All are in agreement that the provisions of Deuteronomy 20:5-8 that apply to discretionary wars apply as well to war undertaken “to diminish the heathens.”
This interpretation is contradicted by Me’iri in his commentary on Sotah 43a. Me’iri declares that it is the Sages who deem such war to be commanded while R. Judah regards it as merely “permitted.” Of course, this understanding appears to be at variance with the statement recorded by the Gemara in the name of R. Yoḥanan.
R. Eliezer Waldenberg, Hilkhot Medinah, II, sha’ar 4, chapter 1, secs. 2-3, explains that Me’iri must have posited a dispute between R. Yoḥanan and Rava: R. Yoḥanan declares the sole controversy between the Sages and R. Judah to be entirely a matter of nomenclature having no practical application; Rava contradicts this analysis and, referring directly to the Mishnah, declares that the Sages posit a “commanded” war that is governed by the selfsame regulation that applies to obligatory wars, viz., the nonexclusion from military service of the individuals described in Deuteronomy 20. R. Judah, on the other hand, equates such war with “discretionary” wars and maintains that those persons described in Deuteronomy 20 are conscripted only in obligatory wars but not for service in wars “to diminish the heathens.” The phraseology employed by Rava, “The difference is with regard to [application of the principle that] one who is engaged in performance of a commandment is exempt from the performance of [another] commandment” is understood by Me’iri as referring to exemption from an obligation associated with warfare itself, i.e., the obligation devolving upon those described in Deuteronomy 20 to recuse themselves from battle. That obligation is variously regarded as based upon the words expressed repeatedly in Deuteronomy 20 “let him go and return to his house” or the verse “he shall be free for his house one year” (Deuteronomy 24:5). See Rashi, Deuteronomy 20:7, Sotah 43a, and Rambam, Hilkhot Melakhim 7:10. The Sages regard participation in war “to diminish the heathens” as a miẓvah and hence incumbent upon even those enumerated in Deuteronomy 20. Since participation in a war “to diminish the heathens” constitutes a miẓvah, such participation serves to exempt those enumerated in Deuteronomy 20 from the commandment to remove themselves from the battle arena.
[The Tosefta, Sotah 7:15, as apparently understood by Rashi, Deuteronomy 20:7, and Rambam, Hilkhot Melakhim 7:11, maintains that those exempt from conscription in milḥamot reshut may not serve even on a voluntary basis. See also the discussion in Sotah 44a concerning a prohibition against a bridegroom’s participation in battle. Rabbi Waldenberg’s analysis of Me’iri is apparently predicated upon this premise. One difficulty with this explanation lies in the fact that Rambam, on the basis of Sotah 44a, maintains that military service by such individuals involves, not a simple violation of a positive commandment, but transgression of two negative commandments, viz., “When a man takes a wife he shall not go out in the army, nor shall he be charged with any matter” (Deuteronomy 24:5). The principle that one engaged in fulfillment of a miẓvah is exempt from fulfillment of other precepts applies only to positive commandments but does not permit violation of negative precepts. (The usual explanation of why the exclusions from military service found in Deuteronomy 20 do not apply to commanded or obligatory wars is based upon rabbinic exegesis of the prefatory phrase in that section. “Ki teẓei la-milḥamah” is understood as meaning “If you go forth to war” rather than “When you go forth to war.” The reference must then be to discretionary war since commanded war cannot be described in hypothetical terms.)
See also Sefer ha-Ḥinnukh, no. 581, who apparently maintains that the exclusion of those enumerated in Deuteronomy 20 means simply that they cannot be compelled to perform military service but does not forbid voluntary enlistment. If so, the phrase “let him go and return to his house” cannot be understood as a miẓvah. However, Rava’s comment may be understood in an alternative manner. It may be understood to mean that the dispute between the Sages and R. Judah is also with regard to application of the principle that one who is engaged in fulfillment of a commandment is exempt from the fulfillment of another commandment. It would be regarded as self-understood that exemption or non-exemption from participation in a war “to diminish the heathens” flows from its categorization as miẓvah or reshut. See Knesset ha-Gedolah, Hilkhot Melakhim, chapter 5, appended to Knesset ha-Gedolah, vol. IV.]
Rabbi Waldenberg finds support for Me’iri’s interpretation in the parallel discussion found in the Palestinian Talmud that reports that R. Yoḥanan declared that the dispute between the Sages and R. Judah is entirely one of nomenclature, while R. Ḥisda declared that there is a substantive dispute between them. The identical controversy, according to this analysis, is posited by the Babylonian Talmud as a dispute between R. Yoḥanan and Rava.
This analysis of Me’iri’s comments yields a conclusion of crucial halakhic import. In this controversy the normative halakhah is decided in accordance with the majority position, i.e., that of the Sages. According to the interpretation of Me’iri, the Sages maintain that war to diminish the heathens is a milḥemet miẓvah rather than a milḥemet reshut.
It should, however, be noted that there is a distinct possibility that the text of the Me’iri’s commentary contains a scribal error and that Me’iri actually wrote that war “to diminish the heathens” is a milḥemet miẓvah according to R. Judah but a milḥemet reshut for the Sages. In citing the text of Me’iri’s remarks, R. Shlomoh Yosef Zevin, Le-Or ha-Halakhah (Tel Aviv, 5717), p. 13, makes precisely this correction without further comment.
Knesset ha-Gedolah, IV, Hilkhot Melakhim, chapter 5, similarly explains that there is a dispute between R. Yoḥanan and Rava. According to Knesset ha-Gedolah, Rava declares that both the Sages and R. Judah maintain that war “to diminish the heathens” is a milḥemet miẓvah in the sense that the exemptions recorded in Deuteronomy 20 do not apply in the conduct of such warfare. The sole dispute is whether combatants engaged in such warfare are exempt from fulfilling other precepts. According to the Sages they are exempt while according to R. Judah they are not exempt. For that reason R. Judah terms such war milḥemet reshut, i.e., participants are not viewed as engaged in an activity exempting them from fulfillment of other precepts. It is the view of Knesset ha-Gedolah that Rambam rules in accordance with the opinion of the Sages and includes preemptive war in the category of war “to deliver Israel from an enemy” which is classified by Rambam as a milḥemet miẓvah. This interpretation of Rambam is, however, contradicted by Rambam’s own comments in his Commentary on the Mishnah, Sotah, 8:7; see below, note 14.

He prohibited a groom from leaving his home in order to be involved with one of the burdens for an entire year - not to go out to war, and not for anything besides it. Rather we remove every burden and onus that he is obligated, to leave them the entire year. And that is His saying, "neither shall he be charged with any matter; he shall be free for his home" (Deuteronomy 24:5). And the Gemara, Sotah (Sotah 44a): "'He shall not go out with the army'; it is possible that with the army he does not go out, but he does fix weapons and supplies water and food. [Hence] we learn to say, 'neither shall he be charged [with any matter.' Perhaps it is that I include even one who has built a house and has not dedicated it, one who has planted a vineyard and has not redeemed it [and] one who has betrothed a woman and has not taken her? (Hence) we learn to say, 'he be charged'] - you do not charge him, but you do charge others. But since it is derived from, 'neither shall he be charged,' why do I need, 'He shall not go out with the army?' So that he will transgress two negative statements." However we have already explained in Principle 9 that not everything for which we would be liable for two negative statements are [counted separately as] two commandments. And know that the groom himself is prohibited from going out of his house for trade the entire year (In Radbaz Part I:238, he wrote that this is a copier's mistake). And the regulations of this commandment have already been explained in Chapter 8 of Sotah. (See Parashat Shoftim; Mishneh Torah, Kings and Wars 6-7.)

That a groom should not go out from his home the whole year, even for the needs of the community: That the groom is prevented from going out from his house the entire [first] year, meaning to say to go on distant trips. And also the army officer is prevented from taking him out by force, meaning to say, from taking him out to war or to do work needed for the war - for example, to supply water and food to his brothers or to fix matters in the city, to guard it from the enemy. And about this is it stated (Deuteronomy 24:5), "nor have any purpose assigned to him." And they said in Tractate Sotah 44a, "'He shall not go out with the army' - it is possible that with the army he shall not go out, but he should fix weapons or supply water and food; [hence] it is taught to say, 'nor have any purpose assigned to him.'" And they inferred further,"[it is] 'to him' that you do not assign, but you do assign to others," meaning to say to those that return from the war because of weak-heartedness, or because of the dedication of a house or vineyard. And there they also said, "And since it comes out from 'nor have assigned to him,' why do I have 'he shall not go out with the army?' To have him transgress on two negative commandments."