Is Reading the Megilla on the 15th a Separate Mitzva from Reading on the 14th?
At the heart of the debate about the Megilla reading schedule of perazim and mukafim (perazi = one who lives in an open city who would generally read on the 14th, mukaf = one who dwells in a walled city who would normally read on the 15th) lies a crucial debate between the Ri"f and the Ba'al Hama'or. The Mishna (19a) already recognizes the possibility that a mukaf will visit a peraz city or perazi will visit a mukaf during Purim. How might this dislocation affect their reading schedule. The Mishna determines that if he will ultimately return to his natural home in time, he must read according to his original schedule. If he will not return in time he must read according to the local schedule. The gemara cites Rava who informs us that 'on time' means returning to a peraz city by the morning of the 14th or returning to a mukaf by the morning of the 15th. Namely, if a traveler will make it back to his city by the morning of his host city's Purim, he should schedule his reading according to his original location. If he will miss that crucial period and will be located in the new city during the morning of that city's Purim he should adopt the schedule of his new surroundings and plan accordingly.
The Rif and the Rabenu Chananel each introduce a new factor to the Mishna's statement. The simple reading of the gemara suggests that presence in a different city during the crucial moment of chiyuv is sufficient to alter his schedule. The Rif maintains that intended presence is necessary. If, for example, a perazi visited a mukaf and planned to return to his peraz by the morning of the 14th and became accidentally delayed, he still assumes the perazi schedule of reading on the 14th even though he physically was located in a mukaf on the 14th. The schedule is not determined solely by presence but by conscious presence. The Ba'al Hama'or rejects the Rif's contention and adopts the simple reading that physical presence alone determines the schedule.
In his defense of the Rif, the Ramban strikes a fascinating analogy which might yield insight into the Rif's position. To prove the Rif's idea the Ramban cites the precedent of halakhot cited primarily in the 4th perek of Pesachim which also discusses applying different halakhic mores upon travelers. Some of the examples cited by the gemara include: different schedules of issur melakha on Erev Pesach, keeping one day or two days of Yom Tov, and selling smaller animals to gentiles (which can invite certain halakhic problems). A visitor only absorbs the standards of his host area when he doesn't plan to return. If he plans to return he does not possess a fundamental obligation to adhere to the standards of his new location. Similarly, asserts the Ramban, applying different standards to visitors on Purim depends solely upon the intended itinerary. This association assumes that our Mishna's halakha is based upon the general concept of applying local halakhot to visitors under certain circumstances.
Reading the gemara's statements though suggests a different way to understand our halakha. Rava actually provides a source for applying perazi standards to visiting mukafin or by extension mukaf standards to visiting perazim. The derasha determines that a peraz for a day (a mukaf found in a peraz city for Purim) can be considered a peraz for Megilla purposes. If our halakha is based upon the general concept of applying local standards to visitors we must wonder at the need for a specific pasuk. The provision of a special pasuk does indeed suggest a new paradigm!!!
The gemara in Pesachim describes situations in which the same halakha or mitzva was performed differently in different locations. For example, the issur of working on Erev Pesach. A prohibition to work after chatzot applies universally while several locales extended the issur from the start of the morning. As the same halakha is practiced differently we must carefully consider the terms for applying local standards to visitors. In the case of reading the Megilla we might be dealing with two different mitzvot which apply to people based upon their location. A peraz is obligated in reading the Megilla on the 14th while a mukaf is obligated to the 15th and each is obligated to a separate mitzva. A clear signal toward this definition is provided by the Ramban himself who rules that conceivably one person can be obligated to read to Megilla on two separate days. If a mukaf visits a peraz and does not plan to return by the morning of the 14th he is obligated to read on the 14th. If he subsequently returns to his home mukaf city he then must read a second time. The possibility of reading the Megilla on two separate occasions indicates that this gemara is not just addressing ONE mitzva which is performed differently in different locations. The mitzva of reading the Megilla is really two different mitzvot and location determines which mitzva will devolve. As noted in an earlier shiur a peraz cannot be motzi a mukaf on the 15th (even if he hasn't already read) since he is not commanded in the Megilla reading of the 15th.
Viewing the two dates as two separate mitzvot (rather than one mitzva practiced differently) justifies the need for a special pasuk and unique derasha. The gemara in Pesachim already teaches us that local standards are sometimes applied to visitors. Rava's halakha teaches us that temporary dwelling can confer a local status which might obligate a visitor in his host town's mitzva in place of (or even IN ADDITION to his natural mitzva). From this standpoint the Ba'al Hama'or has a cogent point. Just because the intended itinerary influence the imposition of local standards in Pesachim does not mean that it should figure equivalently in determining personal status on Purim. On Purim the definition of personal status would impact which mitzva a person is obligated in. Mere physical presence would be sufficient to convey that status.
An additional scenario which might indicate the presence of distinct mitzvot - rather than one mitzva practiced differently - would be a situation in which someone is excused from both dates of the mitzva. The Yerushalmi in Megilla (2:3) discusses someone who travels in the desert on Purim. The Rabanan suggest that, as he hasn't assumed a new location, he should continue to read based on his home custom. Rav Manah issues a statement which the Ritva in Megilla understands in a novel manner. He should only read based upon his original schedule if he plans to return to his home or a similar town. If his ultimate plans include moving to a mukaf (having previously lived in a peraz) he does not read at all. He has abdicated his status as perazi and has no plans to assume a status as mukaf. This scenario clearly indicates the presence of two mitzvot and the role of geographic identity in imposing the mitzva.
This question, whether the 14th and the 15th entail one mitzva practiced differently or two entirely different mitzvot would impact and interesting question raised by some Poskim. The gemara suggests that the different schedules of 14 and 15 apply not just to the town's proper but to some of its suburbs. Suburbs of a mukaf with visual contact would also read on the 15th. What would happen if someone travels from a mukaf to a suburb of a peraz. Would his presence in the suburb also impose a temporary status of perazi thereby forcing him to read on the 14th? Indeed, if held up to Pesachim standards, as he now finds himself among a community of people who will read on the 14th he might have to conform to that new standard. If however we are trying to determine whether his presence creates a temporary status as perazi we might claim that temporary presence in the city proper is sufficient to impose the new standard. Temporary presence in a suburb does not convey the new standard, even though he finds himself with people who, as permanent residents of the suburb, will be reading on the 14th.
Purim sameach to all Am Yisrael.