According to Hebrew University's Melton program, Leon Weiner Dow:
Dow is obviously a smart man.
But being smart doesn't always directly correlate with being correct.
Dow published an article last year in Hebraic Political Studies. Opposition to the 'Shulchan Aruch: Articulating a Common Law Conception of Halacha intends to show that Karo''s and the Rama's work stifled the previously existing common law interpretation of halacha, meaning each rabbi decided the law based on his own understanding of relevant Talmudic texts and local custom.
Dow opens this way:
…
The problem?
The Rosh (1259-1328) was not a Sefardi. He was the premier halakhic authority in the Ashkenazic world of his day. Forced to flee Ashkenaz for Spain, where, at the urging of the Rashba, he became rabbi of Toledo. The Rosh is noted for, among other things, bringing Ashkenazi strictness to Spain.
But Dow's error doesn't stop there. Why? Because the Rif, Isaac Alfasi (1013 - 1103), wasn't Sefardi either. Alfassi, who lived in Fez, Morocco, was Mizrachi. Mizrachi communities did not become Sefardi until much later, after Spanish exiles flooded Morocco, Tunisia and other countries of Mizrach after 1492.
In 1088, when he was 75 years old, the Rif was forced to flee Fez and found refuge in Spain. Like the Rosh, the Rif is also credited with bringing a new halakhic strictness to Spain.
Maimonides (1135 - 1204), the Rambam, was born in Spain but fled persecution, eventually settling in Egypt. Of the three sources Yosef Karo relied on, the Rambam is most authentically Sefardi, although his teacher's teacher was trained in Fez.
So what Yosef Karo actually did is take the halakhic decisions of the leading Ashkenazic, Sefardic, and North African codifiers and use them to reach his halakhic decisions.
The way Karo did this most often was to follow the majority. For example, if the Rambam and the Rosh permitted something the Rif forbade, the Shulchan Aruch would follow the Rambam and the Rosh.
This is a remarkably ecumenical approach, especially if you look at the Jewish population distribution at the time of Yosef Karo's birth in 1488. At most, there were perhaps 50,000 Ashkenazic Jews in Europe. Spain and Portugal combined had approximately 500,000 Jews (although there are claims of 800,000 at the time of the Expulsion from Spain), and North African communities combined had perhaps another 30,000.
While Georgian Jews (loosely defined as Mizrachi), Chinese Jews, Indian Jews, Ethiopian Jews and Yemeni Jews are left out of this mix (as are non-Ashkenazi/non-Sefardi Italian Jews, although their community was very small), in terms of available rabbinic scholarship Karo's three sources cover the vast majority of the known Jewish world and its rabbinic scholarship.
(Chinese, Ethiopian and Indian Jews were not rabbinic and were also largely unknown to rabbinic Jewry, while Yemeni Jews followed – and still follow – the Rambam – with Yosef Karo's blessing.)
So what Dow claims is not only false, it completely misrepresents what Karo was trying to do.
Dow goes on to list the Maharshal, Maharal of Prague and the maharal's brother as students of the Rama:
Despite the footnote, Dow cites no source for this claim.
The four were all about the same age. Shlomo Luria was the Rama's older cousin. If anything, Luria taught the others.
Dow then launches into a history of halakhic code writing in Ashkenaz and Poland, followed by the opposition to the Shulchan Aruch by Luria, the Maharal and his brother.
Missing from this is one rather important event – the Expulsion from Spain which dispersed and impoverished the largest and most prosperous Jewish community in the world– and any discussion of how that event impacted the halakhic thinking of Yosef Karo and the Rema.
Before the Expulsion, the "common law" Judaism Dow mourns existed everywhere. But the Expulsion changed that by interjecting tens of thousands of Sefardim into previously homogeneous or near- homogeneous communities.
Sefat in North of the Land of Israel, where Karo lived when he wrote the Shulchan Aruch, was a dizzying mix of expelled Sefardim and Jews from all over North Africa, Turkey and even a few from Ashkenaz.
Communities all over North Africa and Turkey were similarly mixed. Even Poland now had a large contingent of Sefardic Jews, among them the ancestors of Schneur Zalman of Liady, the first Chabad rebbe.
This sudden intermixing created a situation where, for the first time, Jews living side by side followed Jewish law differently.
What Karo tried to do was create a basic uniform code that all Jews could follow, a code that would give equal weight to each of the three basic geographic divisions of Rabbinic Judaism and would bring peace between neighbors.
Sefardi rabbinic leaders eventually accepted this code not because it favored them, but because it recognized their now dispersed community – which pre-expulsion made up about 75% of Rabbinic Jewry, and post-Expulsion, factoring in deaths and conversions, still in aggregate made up well over half of the world's Rabbinic Jews. Along with Mizrachi rabbinic leaders, they also came to believe unified practice and the communal peace they expected it to bring outweighed preserving differences in halakhic practice.
Ashkenazim did not make the same assessment, perhaps because the number of Spanish exiles in Ashkenaz and Poland was relatively small.
The three rabbinic leaders who opposed the Rama's commentary on the Shulchan Aruch opposed it in part because they wanted to maintain communal differences within Ashkenazic Europe.
For his part, the Rama favored homogeneity within Ashkenaz. He added Ashkenazi-Polish halakhic decisions issued since the death of the Rosh to and indicated where current Ashkenazic halakhic practice differed from Karo's to facilitate this. In part, his may have been an attempt to protect Ashkenazic practice from adulteration by Spanish exiles who settled in Poland. If so, this desire either was not shared by the Maharshal, Maharal and his brother, or their need to ensure rabbinic independence outweighed any fear of such adulteration.
The Shulchan Aruch was not written in a historical vacuum. Neither was the Rama's Mappa.
Rather than isolated communities, the Expulsion from Spain had transformed the known Jewish world into a heterogeneous mixture.
Yosef Karo reacted to this by trying to create a standardized baseline for all Jews (except, notably Yemeni Jews who he viewed as being under the authority of the Ramabam and whose communities were not notably impacted by exiles from Spain).
The Rama reacted to it by (at least in part) trying to create a standardized baseline for all Ashkenazic Jews.
The Mizrachi-Sefardi communities that accepted the Shulchan Aruch (minus the Rama) as their baseline made up well over 75% of Rabbinic Jewry, dwarfing the small and divided communities of Ashkenaz and Poland.
That demographic fact – and the fact that Spanish exiles moved into Poland throughout the 16th and even early 17th centuries – by the early 1600s encouraged the printing of Karo's Shulchan Aruch and the Rama's Mappa together on the same page, with the Rama's commentary interwoven with Yosef Karo's words.
That combined book, and the commentaries and supra-commentaries that eventually would become part of it, became the standard code of Jewish law.
None of this dramatically weakens Dow's analysis of the specifics of the opposition of the Maharshal, Maharah and Chaim ben Betzalel to the Rama's work.
But it does remove both the Rama and Yosef Karo from their proper historical setting, and their joint work's acceptance from the ferment of those times.
And one must question how anyone with smicha – especially someone completing a PhD at Bar Ilan University based on "constructing a philosophy of halacha" – could think the Rosh and the Rif were Sefardi.