New American Reform Responsa
66. Two Days of Yom Kippur
QUESTION: Logic would demand that Orthodox Jews should observe two days of Yom Kippur. Why has this not been done? (Louise Marcovsky, Pittsburgh PA)ANSWER: As you correctly surmised, traditional Judaism outside the Land of Israel observed two days of all the festivals due to the uncertainty of the calendar; let me review the reasoning. Each new month was established through the actual observation of the moon. The person who saw the new moon appeared at the Temple along with witnesses and the priest declared that a new month had begun (M R H 1.6 ff; 20a ff3. When the precise date of each festival was established by observation in Jerusalem, the message could not arrive on time in Babylonia, and so two days were celebrated in order to assure the celebration of each festival on the proper day (Ber 4b ff; M R H 2.1 ff). It was for the same reason that two days of Rosh Hashanah were observed even within the city of Jerusalem, for the witnesses to the new moon might arrive too late to begin the full observance of the day (R H 30b). Although these calendar reasons ceased to exist when the calendar was fixed by calculation rather than through the observation of the new moon in Jerusalem, the practice of observing two days outside the land of Israel continued. In modern times we Reform Jews abolished the second day of the festivals as no longer necessary and returned to the Biblical observance; subsequently most Conservative congregations have followed the same practice and given as their reason the wish to observe as the State of Israel. Of course, within Israel only one day of the festivals, except Rosh Hashanah has traditionally been observed. Yom Kippur has been observed for only one day as two days of fasting would have presented an undue hardship (R H 30b). There were, however, pietists particularly in Germany who observed Yom Kippur for two days. This custom, as many pietistic customs arose in central Europe; the Ashkenazi mentality led to strictness. The custom was observed by some people, but it never became standard and was strongly opposed by such individuals as Ranenu Asher (Tur Orah Hayim 624; Agur Hil Yom Hakipurim #957).August 1987
If needed, please consult Abbreviations used in CCAR Responsa.