I understand that there are many differences in customs between Ashkenazi and Sefardi Jews, since they follow the rulings of the sages from their own communities. The differences in pronunciation (havara) can be put down to the influence of the local languages, and even the subtle differences in the prayers are according to what their Rabbis decided should be in the prayer book.

The one thing that stumps me, though, is how it came to be that there is a difference in how to put on tefillin. I mean, the day after Moshe taught everyone how to put on tefillin, presumably he taught everyone the same way. And if there were differences in custom, surely it would have been divided by tribe.

So the "day before" the Ashkenazi/Sefardi split happened, you would either have had a uniform custom of wearing tefillin (on the most basic level, winding inwards or winding outwards), else you'd have a generally random sprinkling of different customs, depending on which tribe everyone had come from.

Fast forward to today, where all Sefardim wind their tefillin outwards, and most Ashkenazim wind inwards (excluding minhag "Sfard", which winds outwards, but has a simple minhag for how to wind around the fingers, as opposed to the more intricate winding used by Edot Mizrach). How did that happen? Assuming the Sefardim kept their minhag the same, and the Ashkenazim changed the minhag, on exactly what day (and why?) did some Ashkenazi posek (who?) get up and announce that as of now, we're all going to put on our tefillin differently than we did yesterday?

  • You can ask the same question how can rashi and rabainu tam both ashkenazim and related can have an argument over t'fillin which everyone puts on every day. It seems these things happen.
    – interested
    May 12 '20 at 10:02
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    There were periods in history when tefillin wearing was uncommon: sefaria.org/Shabbat.130a.14?lang=bi sefaria.org/Tosafot_on_Shabbat.49a.6.1?lang=he (@interested)
    – Joel K
    May 12 '20 at 10:11
  • @JoelK I'm not sure that's a satisfying answer. It would mean that the whole of the Ashkenazi community had stopped putting on tefillin, and then one day someone rediscovered the mitzvah, and didn't have any mesorah of how to put them on, so he started winding them inwards, and everyone followed him from there. I dunno, just doesn't sound right. Can you tell the story in a more plausible way?
    – Shaul Behr
    May 12 '20 at 11:30
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    Originally probably no one cared how you wrapped around your fingers. Eventually people liked being consistant and stabilized. Halakhicaly it doesn't really matter
    – Double AA
    May 12 '20 at 12:01
  • @DoubleAA that actually sounds like a pretty plausible answer.
    – Shaul Behr
    May 12 '20 at 12:28