history - What is the explanation for the discrepancy between Seder Olam's chronology and that of historical scholarship?

Rabbi Harav Yaakov Medan (etzion.org.il/en/chapter-12b-daniels-prayer-continued) states: 'According to historical scholarship, the second year of the Persian Darius, when the rebuilding of the Second Temple commenced, was the year 521 B.C.E., and the Second Temple was destroyed in 70 C.E. Thus, according to this system, the Temple stood for 591 years. However, according to a beraita in Seder Olam [which places Creation at 3760 BCE] and the gemara in Bava Batra 4a, the Second Temple stood for only 420 years. Its construction began in the year 3408 and it was destroyed in 3828.' How is this year discrepancy to be explained--an important question for the elucidation of the seventy weeks prophecy of Daniel 9:24-27?*

*'The accepted interpretation in the Talmud (Nazir 32b) and all the commentators is that the "seventy weeks" allude to the 490 years between the destruction of the First Temple and the destruction of the Second Temple. This period includes within it the seventy years of desolation from the destruction of the First Temple until the second year of the reign of Darius (the Persian), when the building of the Second Temple commenced, and the 420 years that the Second Temple stood.' (Medan) In a footnote to this, he says, 'The discrepancy between these two calculations [that of historical scholarship and Seder Olam] is discussed at length in our article and that of C. Chefetz in Megadim 14 on the period of the kings of Persia and Media.' This journal is not accessible to me.

Answer

This excellent source sheet produced by R. Anthony Manning, lists a number of different approaches to resolving the discrepancy:

1. Seder Olam is correct and the conventional chronology is incorrect.

Conventional chronology is incorrect due to Christian manipulation (R. Sa'adia Gaon) or Greek manipulation (R. Alexander Hool).

2. Conventional chronology is correct and Seder Olam is incorrect.

To quote directly from footnote 1 in R. Manning's source sheet:

Mitchel First’s book gives a comprehensive account of over 100 different Jewish responses on this issue! He lists a number of respected orthodox thinkers who take different positions. These include: (i) some who follow the C.C. [conventional chronology] without even mentioning S.O. [Seder Olam], such as R. Hertz in his Chumash, R. Shlomo Riskin, and R. Emmanuel Rackman; (ii) some who quote both systems, without deciding in either direction, such as R. Aryeh Kaplan and R. Ya’akov Meidan; (iii) some who consider that S.O. is not to be taken literally, such as R. Mordechai Breuer ... It is interesting to note that the Da’at Mikrah Tanach published by Mossad HaRav adopts C.C.

_{Mitchell First's book mentioned above is the one listed here on amazon.com.}

3. Conventional chronology is correct and Seder Olam was intentionally adjusted.

Seder Olam was adjusted in order to obscure the date of the Messiah's arrival (R. Shimon Schwab), to line up the '2000 years of Torah' with the production of the Mishnah (Epstein / Dickman / Wilamowsky), to connect the Jewish year count with the 'minyan shtarot' system (R. Menachem Leibtag), or to hide the failures of the Jews to return to Zion at the start of the Second Temple period (R. Menachem Leibtag).